NUVEEN TAX FREE UNIT TRUST SERIES 990
487, 1998-03-25
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<PAGE>
                                                    FILE NO. 333-46763
                                                    40 ACT FILE NO. 811-2271
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                AMENDMENT NO. 1
                                       TO
                                    FORM S-6
 
For  Registration  under  the  Securities  Act of  1933  of  Securities  of Unit
Investment Trusts Registered on
Form N-8B-2
 
   
<TABLE>
<S> <C>                 <C>
A.  Exact name of Trust: NUVEEN TAX-FREE UNIT TRUST, SERIES 990
 
B.  Name of Depositor:  JOHN NUVEEN & CO. INCORPORATED
 
C.  Complete address of Depositor's principal executive offices:
 
                        333 West Wacker Drive
                        Chicago, Illinois 60606
 
D.  Name and complete address of agents for service:
 
                        JOHN NUVEEN & CO. INCORPORATED
                        Attn: Gifford R. Zimmerman
                        333 West Wacker Drive
                        Chicago, Illinois 60606
 
                        CHAPMAN AND CUTLER
                        Attn: Eric F. Fess
                        111 West Monroe Street
                        Chicago, Illinois 60603
 
It is proposed that this filing will become effective (check appropriate box)
 
/ / immediately upon filing pursuant to paragraph (b)
 
/ / on March 25, 1998 pursuant to paragraph (b)
/ / 60 days after filing pursuant to paragraph (a)
 
/ / on March 25, 1998 pursuant to paragraph (a) of rule 485 or 486
E.  Title of  securities  being registered:  Units  of undivided  fractional  beneficial
    interest.
 
F.  Approximate  date of proposed sale  to the public: As  soon as practicable after the
    effective date of the Registration Statement.
 
/X/ Check box if it is proposed that this filing will become effective on March 25, 1998
    at 1:30 P.M. pursuant to Rule 487.
</TABLE>
    
 
<PAGE>
                     NUVEEN TAX-FREE UNIT TRUST, SERIES 990
 
                             CROSS-REFERENCE SHEET
 
                    PURSUANT TO RULE 404(C) OF REGULATION C
                        UNDER THE SECURITIES ACT OF 1933
 
                (FORM N-8B-2 ITEMS REQUIRED BY INSTRUCTION 1 AS
                           TO PROSPECTUS ON FORM S-6)
 
<TABLE>
<C>  <S>  <C>                                          <C> <C>
FORM N-8B-2                                                FORM S-6
ITEM NUMBER                                                HEADING IN PROSPECTUS
 
          I. ORGANIZATION AND GENERAL INFORMATION
 1.  (a)  Name of trust                                 )  Prospectus Part A -- Cover Page
     (b)  Title of securities issued                    )
 2.  Name and address of Depositor                      )  Information About the Sponsor
 3.  Name and address of Trustee                        )  Information About the Trustee
 4.  Name and address of principal Underwriter          )  Information About the Sponsor
 5.  Organization of trust                              )  What Is The Nuveen Tax-Free Unit Trust?
 6.  Execution and termination of Trust Agreement       )  What Is The Nuveen Tax-Free Unit Trust?
                                                        )  Information About The Trustee
                                                        )  Other Information
 7.  Changes of Name                                    )  *
 8.  Fiscal Year                                        )
 9.  Litigation                                         )
 
          II. GENERAL DESCRIPTION OF THE TRUST AND SECURITIES OF THE TRUST
10.  General Information regarding trust's securities   )  Summary of Portfolios
                                                        )  Why and How are the Bonds Insured?
                                                        )  When Are Distributions Made to Unitholders?
                                                        )  Ownership and Transfer of Units
                                                        )  How Units May Be Redeemed Without Charge?
                                                        )  How Bonds May Be Removed From The Trusts?
                                                        )  Information About the Trustee
                                                        )  Information About the Sponsor
                                                        )  Other Information
                                                        )  What Is The Tax Status of Unitholders?
11.  Type of securities comprising units                )  What Is The Nuveen Tax-Free Unit Trust?
                                                        )  Summary of Portfolios
                                                        )  Composition of Trusts
                                                        )  What Are The Objectives Of The Trusts?
                                                        )  Why and How are the Bonds Insured?
12.  Certain information regarding                      )  *
     periodic payment certificates                      )
13.  (a)  Load, fees, expenses, etc.                    )  Part A -- Essential Information
                                                        )  How Is The Public Offering Price Determined?
                                                        )  Market For Units
                                                        )  What Is Accrued Interest?
                                                        )  What Are Estimated Long Term Return
                                                        )  And Estimated Current Return?
                                                        )  How Was The Price Of The Bonds
                                                        )  Determined At The Date of Deposit?
                                                        )  What Are Normal Trust Operating Expenses?
                                                        )  When Are Distributions Made To Unitholders?
                                                        )  Summary Of Portfolios
                                                        )  How Detailed Are Reports To Unitholders?
     (b)  Certain information regarding                 )  *
          periodic payment certificates                 )
</TABLE>
<PAGE>
<TABLE>
<C>  <S>  <C>                                          <C> <C>
     (c)  Certain percentages                           )  How Is The Public Offering Price Determined?
                                                        )  Market For Units
                                                        )  What Are Estimated Long Term Return
                                                        )  And Estimated Current Return?
                                                        )  How Was The Price Of The Bonds
                                                        )  Determined At The Date Of Deposit?
                                                        )  What Is Accrued Interest?
     (d)  Certain other fees, etc. payable by holders   )  How Was The Price Of The Bonds Determined
                                                        )  At The Date Of Deposit?
                                                        )  What Are Normal Trust Operating Expenses?
                                                        )  Ownership And Transfer Of Units
     (e)  Certain profits receivable by depositor,      )  Composition Of Trusts
          principal underwriter, trustee or             )
          affiliated persons                            )
                                                        )  How Units May Be Purchased By The Sponsor
 
     (f)  Ratio of annual charges to income             )  *
14.  Issuance of trust's securities                     )  Summary of Portfolios
                                                        )  When Are Distributions Made To Unitholders?
                                                        )  Ownership and Transfer of Units
                                                        )  How Units May Be Redeemed Without Charge
15.  Receipt and handling of payments                   )  *
     from purchasers                                    )
16.  Acquisition and Disposition of                     )  What Is The Nuveen Tax-Free Unit Trust?
     Underlying Securities                              )
                                                        )  Summary of Portfolios
                                                        )  Composition of Trusts
                                                        )  Why and How are the Bonds Insured?
                                                        )  How Units May Be Redeemed Without Charge
                                                        )  How Bonds May Be Removed From The Trusts
                                                        )  Other Information
17.  Withdrawal or redemption                           )  Market For Units
                                                        )  How Units May Be Redeemed Without Charge
                                                        )  How Units May Be Purchased By The Sponsor
18.  (a)  Receipt and disposition of income             )  Summary of Portfolios
                                                        )  When Are Distributions Made To Unitholders?
                                                        )  How Detailed Are Reports To Unitholders?
     (b)  Reinvestment of distributions                 )  Accumulation Plan
     (c)  Reserves or special funds                     )  Summary of Portfolios
                                                        )  When Are Distributions Made To Unitholders?
     (d)  Schedule of distributions                     )  *
19.  Records, accounts and reports                      )  When Are Distributions Made To Unitholders?
                                                        )  How Detailed Are Reports To Unitholders?
20.  Certain miscellaneous provisions of                )  Information About the Trustee
     Trust Agreement                                    )
                                                        )  Information About the Sponsor
                                                        )  Other Information
21.  Loans to security holders                          )  *
22.  Limitations on liability                           )  Summary of Portfolios
                                                        )  Composition of Trusts
                                                        )  Information About The Trustee
23.  Bond arrangements                                  )  *
24.  Other material provisions of Trust Agreement.      )  *
 
          III. ORGANIZATION, PERSONNEL AND AFFILIATED PERSONS OF DEPOSITOR
25.  Organization of Depositor                          )  Information About the Sponsor
</TABLE>
<PAGE>
<TABLE>
<C>  <S>  <C>                                          <C> <C>
26.  Fees received by Depositor                         )  *
27.  Business of Depositor                              )  Information About the Sponsor
28.  Certain information as to officials                )  *
     and affiliated persons of Depositor                )
29.  Voting Securities of Depositor                     )  Information About the Sponsor
30.  Persons controlling Depositor                      )
31.  Payments by Depositor for certain                  )
     services rendered to trust                         )
32.  Payments by Depositor for certain                  )  *
     other services rendered to trust                   )
33.  Remuneration of employees of Depositor             )
     for certain services rendered to trust             )
34.  Remuneration of other persons for                  )
     certain services rendered to trust                 )
 
          IV. DISTRIBUTION AND REDEMPTION OF SECURITIES
35.  Distribution of trust's securities by states       )  *
36.  Suspension of sales of trust's securities          )
37.  Revocation of authority to distribute              )
38.  (a)  Method of distribution                        )
     (b)  Underwriting agreements                       )  How Units of The Trusts Are
                                                        )  Distributed To The Public
     (c)  Selling agreement                             )
39.  (a)  Organization of principal underwriter         )  Information About The Sponsor
     (b)  NASD membership of principal underwriter      )
40.  Certain fees received by principal underwriter     )  *
41.  (a)  Business of principal underwriter             )
     (b)  Branch offices of principal underwriter       )  *
     (c)  Salesmen of principal underwriter             )
42.  Ownership of trust's securities by                 )  *
     certain persons                                    )
43.  Certain brokerage commissions received             )  *
     by principal underwriter                           )
44.  (a)  Method of valuation                           )  Part A -- Essential Information
                                                        )  How Is The Public Offering Price Determined?
                                                        )  How Was The Price Of The Bonds
                                                        )  Determined At The Date of Deposit?
                                                        )  What Are Normal Trust Operating Expenses?
     (b)  Schedule as to offering price                 )  *
     (c)  Variation in offering price to                )  How Is the Public Offering Price
          certain persons                               )  Determined?
                                                        )  What Is Accrued Interest?
                                                        )  How Was The Price Of The Bonds
                                                        )  Determined At The Date of Deposit?
45.  Suspension of redemption rights                    )  *
46.  (a)  Redemption valuation                          )  Unit Value and Evaluation
                                                        )  How Units May Be Redeemed Without Charge
                                                        )  How Units May Be Purchased By The Sponsor
     (b)  Schedule as to redemption price               )  *
47.  Maintenance of position in underlying              )  How Is the Public Offering Price
     securities                                         )  Determined?
                                                        )  How Units May Be Purchased By The Sponsor
</TABLE>
<PAGE>
<TABLE>
<C>  <S>  <C>                                          <C> <C>
          V. INFORMATION CONCERNING THE TRUSTEE OR CUSTODIAN
48.  Organization and regulation of Trustee             )  Information About The Trustee
49.  Fees and expenses of Trustee                       )  Part A -- Essential Information
                                                        )  What Are Normal Trust Operating Expenses?
50.  Trustee's lien                                     )  What Are Normal Trust Operating Expenses?
                                                        )  When Are Distributions Made To Unitholders?
 
          VI. INFORMATION CONCERNING INSURANCE OF HOLDERS OF SECURITIES
51.  Insurance of holders of trust's securities         )  *
 
          VII. POLICY OF REGISTRANT
52.  (a)  Provisions of trust agreement with            )  What Are Normal Trust Operating
          respect to selection or elimination           )  Expenses?
          of underlying securities                      )
                                                        )  How Units May Be Redeemed Without Charge
                                                        )  How Bonds May Be Removed From The Trusts
     (b)  Transactions involving elimination            )  *
          of underlying securities                      )
     (c)  Policy regarding substitution or              )  Summary of Portfolios
          elimination of underlying securities          )
                                                        )  Composition of Trusts
                                                        )  How Bonds May Be Removed From The Trusts
     (d)  Fundamental policy not otherwise covered      )  *
53.  Tax status of trust                                )  What Is The Tax Status Of Unitholders?
 
          VIII. FINANCIAL AND STATISTICAL INFORMATION
54.  Trust's securities during last ten years           )  *
55.                                                     )
56.  Certain information regarding                      )  *
     periodic payment certificate                       )
57.                                                     )
58.                                                     )
</TABLE>
 
- ---------
 
* Inapplicable, omitted, answer negative or not required.
<PAGE>
   
                                 MARCH 25, 1998
                             SUBJECT TO COMPLETION
    
                                           A
   
NUVEEN               NUVEEN MASSACHUSETTS INSURED TRUST 152
                    (NUVEEN TAX-FREE UNIT TRUST, SERIES 990)
    
                                               CUSIP NUMBERS:
   
                                               Monthly:               67065D 375
                                               Quarterly:             67065D 383
                                               Semi-Annually:         67065D 391
    
   
             PROSPECTUS--PART A (SPECIFIC TERMS) -- MARCH 25, 1998
 THIS PART A OF THE PROSPECTUS MAY NOT BE DISTRIBUTED UNLESS ACCOMPANIED BY THE
                                   PART B OF
  THE NUVEEN TAX-FREE UNIT TRUSTS PROSPECTUS DATED JULY 8, 1997, TO WHICH SUCH
                                   REFERENCE
   HEREIN APPLIES. BOTH PARTS OF THE PROSPECTUS SHOULD BE RETAINED FOR FUTURE
                                   REFERENCE.
    
 
   
    Massachusetts  Insured Trust  152 (the "Trust")  consists of  a portfolio of
interest-bearing  obligations  issued  by   or  on  behalf   of  the  State   of
Massachusetts,  certain United  States Territories or  authorities and political
subdivisions thereof which,  in the opinion  of recognized bond  counsel to  the
issuing  authorities, provide income which is exempt from Federal income tax and
Massachusetts income tax, to the extent indicated below.
    
    The objectives of the Trust are income exempt from Federal and state  income
taxes,  and conservation  of capital. The  objectives are,  of course, dependent
upon the continuing  ability of the  issuers, obligors and/or  insurers to  meet
their respective obligations.
   
    The  Portfolio of  the Trust  consists of  8 obligations  issued by entities
located in Massachusetts. The Bonds in the Trust are either general  obligations
of  the governmental  entity issuing  them and  are backed  by the  taxing power
thereof or  are payable  as  to principal  and interest  from  the income  of  a
specific  project or authority  and are not  supported by the  issuer's power to
levy taxes. The sources of payment for the Bonds are divided as follows:
    
 
   
<TABLE>
<CAPTION>
     NUMBER OF                                              PORTFOLIO
      ISSUES                PURPOSE OF ISSUE                PERCENTAGE
  ---------------  ----------------------------------------------------
  <C>              <S>                                     <C>
         3         Education Revenue                            42.8   %
         2         Health Care Facility Revenue                 28.6
         2         General Obligation                           22.9
         1         Bridge and Toll Road Revenue                  5.7
</TABLE>
    
 
   
    Approximately 20.0% of the  aggregate principal amount of  the Bonds in  the
Trust (accounting for approximately 17.1% of the aggregate offering price of the
Bonds)  are original issue discount obligations. Certain of these original issue
discount obligations, amounting to  5.7% of the  aggregate principal amount  and
2.1%  of  the aggregate  offering price  of the  Bonds in  the Trust,  are "zero
coupon" bonds. See "RISK FACTORS" in Part B of this Prospectus for a  discussion
of  the  characteristics  of  such  obligations  and  of  the  risks  associated
therewith.
    
    All of the Bonds in the Trust are covered by policies of insurance  obtained
from  the  MBIA  Insurance  Corporation guaranteeing  payment  of  principal and
interest when due. As a  result of such insurance, the  Bonds in the Trust  have
received  a rating of "Aaa" by Moody's, "AAA" by Fitch, and/or "AAA" by Standard
& Poor's. Insurance does not guarantee the market value of the Bonds or of Trust
Units.
   
    The Trust is  considered to be  concentrated in Bonds  of Education  Revenue
Issuers  whose  revenues  are subject  to  certain risks  including  declines in
"college age" individuals and the possible inability to raise tuition and  fees.
The Trust is also considered to be concentrated in Bonds of Health Care Facility
Revenue  Issuers whose revenues are subject to certain risks including increased
governmental regulation, fluctuating occupancy levels and increased competition.
For a  discussion of  the risks  associated  with investments  in the  bonds  of
various issuers, see "RISK FACTORS" in Part B of this Prospectus.
    
   
                             ESSENTIAL INFORMATION
              REGARDING THE NUVEEN MASSACHUSETTS INSURED TRUST 152
        ON THE BUSINESS DAY PRIOR TO THE DATE OF DEPOSIT, MARCH 24, 1998
    
         Sponsor and Evaluator.......... John Nuveen & Co. Incorporated
         Trustee.............................. The Chase Manhattan Bank
                  -------------------------------------------
 
The  income, expense and distribution data  set forth below have been calculated
for  Unitholders  receiving  monthly,  quarterly  or  semi-annual   distribution
options.
 
   
<TABLE>
<S>                                                   <C>
Principal Amount of Bonds in Trust..................  $     1,750,000
Number of Units.....................................           17,500
Fractional Undivided Interest in Trust Per Unit.....         1/17,500
Public Offering Price--Less than 500 Units
    Aggregate Offering Price of Bonds in Trust......  $     1,669,616
    Divided by Number of Units......................  $         95.41
    Plus Sales Charge 4.9% (5.152% of the Aggregate
     Offering Price of the Bonds per Unit)..........  $          4.92
    Public Offering Price Per Unit(1)...............  $        100.33
Redemption Price Per Unit (exclusive of accrued
  interest).........................................  $         95.03
Sponsor's Initial Repurchase Price Per Unit
  (exclusive of accrued interest)...................  $         95.41
Excess of Public Offering Price Per Unit over
  Redemption Price Per Unit.........................  $          5.30
Excess of Public Offering Price Per Unit over
  Sponsor's Repurchase Price Per Unit...............  $          4.92
Average Maturity of Bonds in the Trust(2)...........       27.4 years
</TABLE>
    
 
- ----------
 
THESE  SECURITIES HAVE  NOT BEEN APPROVED  OR DISAPPROVED BY  THE SECURITIES AND
EXCHANGE COMMISSION NOR HAS THE COMMISSION PASSED UPON THE ACCURACY OR  ADEQUACY
OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
Information   contained  herein  is  subject   to  completion  or  amendment.  A
registration statement  relating to  these securities  has been  filed with  the
Securities  and Exchange  Commission. These securities  may not be  sold nor may
offers to buy be accepted prior  to the time the registration statement  becomes
effective.  This  Prospectus  shall  not  constitute an  offer  to  sell  or the
solicitation of an offer to buy nor shall there be any sale of these  securities
in  any State in which such offer,  solicitation or sale would be unlawful prior
to registration or qualification under the securities laws of any State.
 
                                     1 of 7
<PAGE>
                         ESSENTIAL INFORMATION (CONT.)
 
   
<TABLE>
<CAPTION>
                                                  MONTHLY        QUARTERLY      SEMI-ANNUAL
                                                -----------     -----------     -----------
  <S>                                           <C>             <C>             <C>
  Calculation of Estimated Net Annual
    Interest Income Per Unit
      Annual Interest Income(3)............        $ 4.8643        $ 4.8643       $ 4.8643
      Less Estimated Annual Expense........         $ .2580         $ .2260        $ .2070
                                                -----------     -----------     -----------
      Estimated Net Annual Interest
        Income(4)..........................        $ 4.6063        $ 4.6383       $ 4.6573
  Daily Rate of Accrual Per Unit...........        $ .01279        $ .01288       $ .01293
  ESTIMATED CURRENT RETURN(5)..............            4.59%           4.62%          4.64 %
  ESTIMATED LONG TERM RETURN(5)............            4.65%           4.69%          4.71 %
  Trustee's Annual Fees(6).................        $ 1.4879        $ 1.1679       $ 0.9779
Date of Deposit.....................................................................................March 25, 1998
Settlement Date.....................................................................................March 30, 1998
Mandatory Termination Date....................................See "OTHER INFORMATION" in Part B of this Prospectus
Minimum Value of Each Trust...................................See "OTHER INFORMATION" in Part B of this Prospectus
Sponsor's Annual Evaluation Fee.........................................$0.17 per $1,000 principal amount of Bonds
Estimated Annual Organizational and Offering Expenses(7)..........................................$.02971 per Unit
- ----------
</TABLE>
    
 
The evaluation time for purpose  of sale, purchase or  redemption of Units is  4
p.m. Eastern time or as of any earlier time at which the New York Stock Exchange
closes.  (See "HOW IS THE  PUBLIC OFFERING PRICE DETERMINED?"  in Part B of this
Prospectus.)
 
   
(1) Units are offered at  the Public Offering Price  plus accrued interest  from
    the  preceding Record  Date to,  but not  including, the  date of settlement
    (normally three business days  after purchase). The Date  of Deposit of  the
    Fund  has  been  designated  as  the First  Record  Date  for  all  plans of
    distribution of the Trust and, accordingly, for Units purchased on the  Date
    of Deposit, $.06 of accrued interest to the Settlement Date will be added to
    the  Public Offering Price.  (See "WHAT IS  ACCRUED INTEREST?" in  Part B of
    this Prospectus.)
    
 
(2) The Average Maturity  of Bonds  in the Trust  is calculated  based upon  the
    stated  maturities of the Bonds in the  Trust (or, with respect to Bonds for
    which funds or securities have been placed in escrow to redeem such Bonds on
    a stated call  date, based  upon such call  date). The  Average Maturity  of
    Bonds  in the  Trust may  increase or  decrease from  time to  time as Bonds
    mature or are called or sold.
 
(3) Assumes delivery of  all Bonds.  (See "COMPOSITION OF  TRUSTS" appearing  in
    Part  B of this  Prospectus.) Interest income does  not include accretion of
    original issue  discount on  "zero coupon"  Bonds, Stripped  Obligations  or
    other  original issue discount Bonds. (See "RISK  FACTORS" in Part B of this
    Prospectus.)
 
(4) The amount and  timing of interest  distributions from the  Trust under  the
    various  plans of distribution  are set forth below.  It is anticipated that
    the amount of interest to  be distributed per Unit  in each year under  each
    plan  of distribution will initially be substantially equal to the Estimated
    Net Annual Interest Income per Unit for that plan. The amount of interest to
    be distributed  annually  per  Unit,  will generally  change  as  Bonds  are
    redeemed, mature or are sold or as fees and expenses increase or decrease.
 
(5) Estimated  Long  Term Return  for the  Trust represents  the average  of the
    yields to  maturity  (or  call)  of  the  Bonds  in  the  Trust's  portfolio
    calculated  in  accordance  with  accepted bond  practices  and  adjusted to
    reflect a compounding factor, expenses and sales charges. Estimated  Current
    Return  is computed by dividing  the Net Annual Interest  Income per Unit by
    the Public Offering  Price, and in  contrast to Estimated  Long Term  Return
    does  not reflect the  amortization of premium or  accretion of discount, if
    any. For  more information  see "WHAT  ARE ESTIMATED  LONG TERM  RETURN  AND
    ESTIMATED CURRENT RETURN?" in Part B of this Prospectus.
 
(6) Each  Trustee annual  fee is per  $1,000 principal amount  of the underlying
    Bonds in  the  Trust  for  that  portion of  the  Trust  that  represents  a
    particular plan of distribution.
 
(7) The  Trust (and  therefore Unitholders)  will bear all  or a  portion of its
    organizational  and  offering  costs  (including  costs  of  preparing   the
    registration  statements, the  trust indenture and  other closing documents,
    registering Units with  the Securities and  Exchange Commission and  states,
    the  initial audit  of the Trust  portfolio, initial  evaluation fees, legal
    fees and the initial fees and expenses of the Trustee but not including  the
    expenses incurred in the printing of preliminary and final prospectuses, and
    expenses  incurred in  the preparation and  printing of  brochures and other
    advertising materials  and any  other  selling expenses)  as is  common  for
    mutual  funds. Total organizational  expenses will be  amortized over a five
    year period. See "WHAT  ARE NORMAL TRUST OPERATING  EXPENSES?" in Part B  of
    this  Prospectus and "Statement of Condition." Historically, the sponsors of
    unit investment trusts have paid all the costs of establishing such trusts.
 
                                     2 of 7
<PAGE>
                             INTEREST DISTRIBUTION
 
    Details of interest distributions  per Unit of the  Trust under the  various
plans  appear in  the following table  based upon estimated  Net Annual Interest
Income at the Date of Deposit:
 
   
<TABLE>
<CAPTION>
                                                                                                          NORMAL
                                                                                                      DISTRIBUTIONS
                                                         1998                          1999              PER YEAR
<S>                                     <C>            <C>            <C>            <C>            <C>
- ----------------------------------------------------------------------------------------------------  --------------
Record Date*..........................        5/1            8/1           11/1            2/1
Distribution Date.....................       5/15           8/15          11/15           2/15
- --------------------------------------------------------------------------------------------------------------------
Monthly Distribution Plan.............  $   .4604(1)                                                  $  4.6063
                                                            --------$.3837 every month--------
Quarterly Distribution Plan...........  $   .4604(1)   $  1.1592(2)   $  1.1592      $  1.1592        $  4.6383
Semi-Annual Distribution Plan.........  $   .4604(1)                  $  2.3274(3)                    $  4.6573
- --------------------------------------------------------------------------------------------------------------------
</TABLE>
    
 
 * Record Dates for  semi-annual distributions  are May  1 and  November 1;  for
   quarterly distributions, they are February 1, May 1, August 1 and November 1.
   Record  Dates  for monthly  distributions are  the first  day of  each month.
   Distribution Dates under each distribution plan are the fifteenth day of  the
   month   in  which  the  respective   Record  Date  occurred.  For  additional
   information see "WHEN ARE  DISTRIBUTIONS MADE TO UNITHOLDERS?"  in Part B  of
   this Prospectus.
 
(1) The  first distribution will  be paid to all  Unitholders, regardless of the
    distribution plan selected.  Such distribution may  be more or  less than  a
    regular monthly distribution.
 
(2) Regular 3-month distribution.
 
(3) Regular 6-month distribution.
 
                           MASSACHUSETTS RISK FACTORS
 
    The  financial condition of the Commonwealth of Massachusetts is affected by
various national, economic,  social and environmental  policies and  conditions.
Additionally,  limitations  imposed by  statute  and voter  initiative  upon the
Commonwealth and its local governments  concerning taxes, bond indebtedness  and
other  matters may constrain the revenue-generating capacity of the Commonwealth
and its local  governments and,  therefore, the ability  of the  issuers of  the
Bonds to satisfy their obligations.
 
    The  economic vitality of the State  and its various regions and, therefore,
the ability of the  State and its  local governments to  satisfy the Bonds,  are
affected  by numerous factors.  The employment in the  Commonwealth has been and
continues to be significantly  and adversely affected  by reductions in  federal
government  spending on  defense-related industries.  The Commonwealth  has many
material future  liabilities, including  an  underfunded retirement  system  and
Medicaid expenditures.
 
    The  Commonwealth is a party to numerous  lawsuits in which an adverse final
decision could materially affect the Commonwealth's governmental operations  and
consequently its ability to pay debt service on its obligations.
 
    In recent years, the Commonwealth of Massachusetts and certain of its public
bodies  and municipalities, particularly  the City of  Boston have faced serious
financial difficulties which  have affected  the credit  standing and  borrowing
abilities  of Massachusetts and its respective entities and may have contributed
to higher  interest rates  on debt  obligations. Standard  and Poor's  currently
rates the Commonwealth's uninsured general obligation bonds at A+, while Moody's
rates these obligations at A1.
 
    Further  information concerning  Massachusetts risk factors  may be obtained
upon written  or  telephonic request  to  the  Trustee as  described  in  "OTHER
INFORMATION -- Supplemental Information" appearing in Part B of this Prospectus.
 
                    TAX STATUS--MASSACHUSETTS INSURED TRUST
 
    For  a discussion of the Federal tax status of income earned on Trust Units,
see "WHAT  IS THE  TAX  STATUS OF  UNITHOLDERS?" appearing  in  Part B  of  this
Prospectus.  Investors should  be aware  that on  August 5,  1997, the President
signed the Taxpayer Relief Act of 1997 (the "Act"). The Act reduces the  maximum
stated marginal tax rate for capital gains for certain investments held for more
than 18 months to 20 percent (10 percent in the case of certain taxpayers in the
lowest  tax bracket). The Act also  includes provisions that would treat certain
transactions designed to reduce or eliminate risk of loss and opportunities  for
gain  (e.g., short  sales, offsetting  notional principal  contracts, futures or
forward contracts, or similar transactions)  as constructive sales for  purposes
of  recognition  of gain  (and not  loss)  and for  purposes of  determining the
holding period.  Potential  investors  should consult  their  own  tax  advisors
regarding the potential effect of the Act on their investment in Units.
 
    In  the opinion  of Edwards &  Angell, special Massachusetts  counsel to the
Trust, based on rulings by the Commissioner of Revenue and under existing law:
 
    For Massachusetts  income tax  purposes, each  Trust will  be treated  as  a
corporate  trust under Section 8 of Chapter 62 of the Massachusetts General Laws
("M.G.L.") and not as a grantor trust under Section 10(e) of M.G.L. Chapter 62.
 
                                     3 of 7
<PAGE>
    The Trust  will not  be held  to be  engaging in  business in  Massachusetts
within  the meaning  of said Section  8 and  will, therefore, not  be subject to
Massachusetts income tax.
 
    Unitholders who are  subject to Massachusetts  income taxation under  M.G.L.
Chapter  62  will not  be required  to  include their  respective shares  of the
earnings of or distributions from the Trust in their Massachusetts gross  income
to  the extent that such earnings or distributions represent tax-exempt interest
excludable from gross  income for Federal  income tax purposes  received by  the
Trust  on  obligations issued  by  Massachusetts, its  counties, municipalities,
authorities, political subdivisions or instrumentalities or by Puerto Rico,  the
Virgin  Islands, Guam, the Northern Mariana  Islands or other possessions of the
United States within the meaning of Section 103(c) of the Internal Revenue  Code
of 1986, as amended ("Massachusetts Obligations").
 
    Unitholders  who are subject  to Massachusetts income  taxation under M.G.L.
Chapter 62  will not  be required  to  include their  respective shares  of  the
earnings  of or distributions from the Trust in their Massachusetts gross income
to the extent that such earnings or distributions are derived from the  proceeds
of  insurance  obtained  by  the  Sponsor  of the  Trust  or  by  the  issuer or
underwriter of an obligation held by the Trust that represent maturing  interest
on  defaulted obligations held  by the Trustee,  if and to  the same extent that
such earnings or distributions would have been excludable from the gross  income
of such Unitholders if derived from interest paid by the issuer of the defaulted
obligation.
 
    Unitholders  which are corporations subject to taxation under M.G.L. Chapter
63 will be required  to include their  respective shares of  the earnings of  or
distributions  from the Trust in their  Massachusetts gross income to the extent
that such  earnings or  distributions represent  interest from  bonds, notes  or
indebtedness of any state, including Massachusetts, except for interest which is
specifically  exempted from  such tax by  the acts authorizing  issuance of said
Massachusetts Obligations.
 
    The Trust's capital gains and/or capital losses which are includable in  the
Federal  gross income  of Unitholders  who are  subject to  Massachusetts income
taxation under M.G.L. Chapter 62, or Unitholders which are corporations  subject
to  Massachusetts taxation under  M.G.L. Chapter 63 will  be included as capital
gains and/or losses in the  Unitholders' Massachusetts gross income, except  for
capital gain which is specifically exempted from taxation under such Chapters by
the acts authorizing issuance of said Massachusetts Obligations.
 
    Unitholders  which are corporations  subject to tax  under M.G.L. Chapter 63
and which are tangible property corporations will not be required to include the
Units when determining the value  of their tangible property. Unitholders  which
are  intangible property corporations will be required to include the Units when
determining their net worth.
 
    Gains or losses realized on sales or redemptions of Units by Unitholders who
are subject  to  Massachusetts  income  taxation under  M.G.L.  Chapter  62,  or
Unitholders  which  are corporations  subject  to Massachusetts  income taxation
under M.G.L. Chapter 63, will be includable in their Massachusetts gross income.
In determining such gain or loss  Unitholders will, to the same extent  required
for  Federal tax purposes,  have to adjust  their tax bases  for their Units for
accrued interest received, if any, on Massachusetts Obligations delivered to the
Trustee after the Unitholders pay for their Units, for amortization of premiums,
if any, on Massachusetts Obligations held by the Trust, and for accrued original
issue discount with respect to each Massachusetts Obligation which, at the  time
the Massachusetts Obligation was issued, had original issue discount.
 
    The  Units  of the  Trust  are not  subject to  any  property tax  levied by
Massachusetts or any political subdivision thereof, nor to any income tax levied
by any such political subdivision. They are includable in the gross estate of  a
deceased  holder  who  is  a  resident  of  Massachusetts  for  purposes  of the
Massachusetts Estate Tax.
 
                                     4 of 7
<PAGE>
   
                     NUVEEN MASSACHUSETTS INSURED TRUST 152
                    (NUVEEN TAX-FREE UNIT TRUST, SERIES 990)
         SCHEDULE OF INVESTMENTS AT THE DATE OF DEPOSIT, MARCH 25, 1998
    
 
   
<TABLE>
<CAPTION>
                                                                                          Ratings(3)           Trustee's
                                                                      Optional       ---------------------   Determination
 Aggregate        Name of Issuer and Title of Issue Represented      Redemption       Standard                of Offering
 Principal         by Sponsor's Contracts to Purchase Bonds(1)      Provisions(2)     & Poor's    Moody's        Price
<C>          <C> <S>                                              <C>                <C>         <C>        <C>
- ---------------------------------------------------------------------------------------------------------------------------
$   250,000      Massachusetts Bay Transportation Authority,         2006 at 101        AAA         Aaa     $       250,950
                   General Transportation System Bonds, 1996
                   Series B, 5.25% Due 3/1/26. (Original issue
                   discount bonds delivered on or about October
                   28, 1996 at a price of 92.944% of principal
                   amount.)(General Obligation Bonds.)
    250,000      Massachusetts Health and Educational Facilities     2007 at 102        AAA         Aaa             246,245
                   Authority, Berklee College of Music Issue,
                   Revenue Bonds, Series E, 5.10% Due 10/1/27.
    250,000      Massachusetts Health and Educational Facilities     2008 at 102        AAA         Aaa             240,510
                   Authority, Catholic Health East Issue, Series
                   1998B, 5.00% Due 11/15/28.
    250,000      Massachusetts Health and Educational Facilities     2007 at 101        AAA         Aaa             253,673
                   Authority, Revenue Bonds, Partners HealthCare
                   System Issue, Series A, 5.375% Due 7/1/24.
    250,000      Massachusetts Industrial Finance Agency,            2007 at 102        AAA         Aaa             242,503
                   Revenue Bonds, Merrimack College Issue,
                   Series 1997, 5.00% Due 7/1/27.
    250,000      Massachusetts Industrial Finance Agency,            2007 at 102        AAA         Aaa             251,033
                   Revenue Bonds, Suffolk University Issue,
                   Series 1997, 5.25% Due 7/1/27.
    100,000      Massachusetts Turnpike Authority, Metropolitan   No Optional Call      AAA         Aaa              35,140
                   Highway System Revenue Bonds, 1997 Series C
                   (Senior), 0.00% Due 1/1/19. (Original issue
                   discount bonds delivered on or about October
                   2, 1997 at a price of 31.574% of principal
                   amount.)
    150,000      City of Chelsea, Massachusetts, General             2008 at 101        AAA         Aaa             149,562
                   Obligation State Qualified Refunding Bonds,
                   5.125% Due 6/15/15.
- -----------                                                                                                 ---------------
$ 1,750,000                                                                                                 $     1,669,616
- -----------                                                                                                 ---------------
- -----------                                                                                                 ---------------
</TABLE>
    
 
- ------------
 
    (1) The Sponsor's contracts to purchase  Bonds were entered into during  the
period from February 24, 1998 to March 24, 1998. Other information regarding the
Bonds in the Trust on the Date of Deposit is as follows:
 
   
<TABLE>
<CAPTION>
                                                           PROFIT (OR
                                              COST TO         LOSS)       ANNUAL INTEREST   BID PRICE
                   TRUST                      SPONSOR      TO SPONSOR     INCOME TO TRUST   OF BONDS
  ----------------------------------------  -----------  ---------------  ---------------  -----------
  <S>                                       <C>          <C>              <C>              <C>
  Massachusetts Insured Trust 152.........  $ 1,665,166  $       4,450    $    85,125      $ 1,662,916
</TABLE>
    
 
   
In  addition,  the difference  between the  Trustee's determination  of Offering
Price and Bid Price (as a percentage of principal amount) is .38%. Neither  cost
to  Sponsor nor  profit (or  loss) to  Sponsor reflects  underwriting profits or
losses received  or  incurred  by  the  Sponsor  through  its  participation  in
underwriting  syndicates. The  Sponsor did  not participate  as either  the sole
underwriter or as a manager or member of a syndicate that acted as the  original
underwriter of any of the Bonds.
    
 
    (2)  The Bonds are first subject to optional redemption in the years, and at
the prices,  shown. Unless  otherwise  indicated, the  Bonds, except  for  Bonds
issued  at a  substantial original issue  discount, are  redeemable at declining
prices (but not below  par value) in subsequent  years. Original issue  discount
bonds,  including zero coupon bonds, are generally redeemable at prices based on
the issue  price  plus  the  amount  of  original  issue  discount  accreted  to
redemption  plus, if applicable, some premium,  the amount of which will decline
in subsequent years. The  Bonds may also be  subject to sinking fund  redemption
without  premium  prior to  the dates  shown.  Certain Bonds  may be  subject to
redemption without  premium prior  to  the date  shown  pursuant to  special  or
mandatory  call provisions specified in the  instruments setting forth the terms
and provisions of  such Bonds.  See "COMPOSITION OF  TRUSTS", "WHAT  IS THE  TAX
STATUS OF UNITHOLDERS?" and "RISK FACTORS" in Part B of this Prospectus.
 
    (3)  All the  Bonds in the  Insured Trusts,  as insured by  the Insurer, are
rated AAA  by  Standard &  Poor's,  AAA by  Fitch  and/or Aaa  by  Moody's.  The
insurance obtained by the Trust guarantees the payment of interest and principal
on  the Bonds when due  but does not cover  certain market risks associated with
fixed income  securities  such  as accelerated  payments,  premiums  payable  on
mandatory  redemptions or interest rate  risks. (See "WHY AND  HOW ARE THE BONDS
INSURED?" in  Part B  of this  Prospectus and  "Description of  Ratings" in  the
Information Supplement.)
 
                                     5 of 7
<PAGE>
                             Statement of Condition
 
   
                     NUVEEN MASSACHUSETTS INSURED TRUST 152
    
 
   
                    (Nuveen Tax-Free Unit Trust, Series 990)
    
 
   
                              AS OF MARCH 25, 1998
    
 
   
<TABLE>
<S>                                                 <C>
    TRUST PROPERTY
Sponsor's contracts to purchase Bonds, backed by
  an irrevocable letter of credit(1)(2)...........  $    1,669,616
Accrued interest to March 25, 1998 on underlying
  Bonds(1)........................................          17,498
Organizational costs(3)...........................           2,600
                                                    --------------
            Total.................................  $    1,689,714
                                                    --------------
                                                    --------------
   LIABILITIES AND INTEREST OF UNITHOLDERS
LIABILITIES:
    Accrued interest to March 25, 1998 on
     underlying Bonds(4)..........................  $       17,498
    Accrued organizational and offering
     costs(3).....................................           2,600
                                                    --------------
            Total.................................  $       20,098
                                                    --------------
                                                    --------------
INTEREST OF UNITHOLDERS:
    Units of fractional undivided interest
     outstanding (17,500)
      Cost to investors(5)........................  $    1,755,635
        Less: Gross underwriting commission(6)....         (86,019)
                                                    --------------
    Net amount applicable to investors............  $    1,669,616
                                                    --------------
            Total.................................  $    1,689,714
                                                    --------------
                                                    --------------
</TABLE>
    
 
- ------------
 
(1) Represented  by contracts to  purchase Bonds which  include "when issued" or
    "regular way"  or  "delayed delivery"  contracts  for which  an  irrevocable
    letter  of credit issued by a major  commercial bank has been deposited with
    the Trustee on the Date of Deposit. The amount of such letter of credit  and
    any  cash deposited  exceeds the  amount necessary  for the  purchase of the
    Bonds plus accrued interest to the Date of Deposit. At the Date of  Deposit,
    Bonds  may have been delivered  to the Sponsor pursuant  to certain of these
    contracts; the Sponsor has assigned to the Trustee all of its rights,  title
    and interest in and to such Bonds.
 
(2) Aggregate  value (at offering prices) as of the Date of Deposit of the Bonds
    listed under "Schedule of Investments"  herein, and their aggregate cost  to
    the  Trust are the same.  Such offering prices were  determined by Kenny S&P
    Evaluation Services, a division of J. J. Kenny Co., Inc., as of the close of
    business on the business day prior to the Date of Deposit. (See "HOW WAS THE
    PRICE OF THE BONDS  DETERMINED AT THE  DATE OF DEPOSIT?" in  Part B of  this
    Prospectus.)  Insurance coverage providing for the timely payment, when due,
    of all principal of and interest on  the Bonds in an Insured Trust has  been
    obtained by the Sponsor or by the issuers of such Bonds. Such insurance does
    not  guarantee the market value of the Bonds or the value of the Units. Both
    the bid and the offering prices of the underlying Bonds and of the Units may
    include value attributable to such policies of insurance.
 
(3) The Trust (and  therefore Unitholders)  will bear all  or a  portion of  its
    estimated  organizational  and offering  costs  which will  be  deferred and
    amortized over five years from the Date of Deposit.
 
(4) Representing, as set forth in "WHAT IS ACCRUED INTEREST?" in Part B of  this
    Prospectus,  advancement by  the Trustee of  an amount equal  to the accrued
    Bond interest as of the Date of Deposit.
 
(5) Aggregate Public Offering Price (exclusive of accrued interest) computed  as
    set  forth under "HOW IS THE PUBLIC OFFERING PRICE DETERMINED?" in Part B of
    this Prospectus.
 
(6) The gross underwriting commission of 4.90% of the Public Offering Price  has
    been  calculated on the assumption that the  Units sold are not subject to a
    reduction of sales  charge for  quantity purchases.  In single  transactions
    involving  500 Units or more, the sales  charge is reduced. (See "HOW IS THE
    PUBLIC OFFERING PRICE DETERMINED?" in Part B of this Prospectus.)
 
                                     6 of 7
<PAGE>
                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
   
TO THE BOARD OF DIRECTORS OF JOHN  NUVEEN & CO. INCORPORATED AND UNITHOLDERS  OF
MASSACHUSETTS INSURED TRUST 152:
    
 
   
    We  have audited the accompanying statement of condition and the schedule of
investments at  date of  deposit (included  in  Part A  of this  Prospectus)  of
Massachusetts Insured Trust 152 (contained in Nuveen Tax-Free Unit Trust, Series
990), as of March 25, 1998. These financial statements are the responsibility of
the  Sponsor. Our  responsibility is  to express  an opinion  on these financial
statements based on our audit.
    
 
    We conducted  our  audit  in accordance  with  generally  accepted  auditing
standards.  Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence  supporting
the amounts and disclosures in the financial statements. Our procedures included
confirmation of the irrevocable letter of credit arrangement for the purchase of
securities,   described  in  Note   (1)  to  the   statement  of  condition,  by
correspondence with the Trustee. An audit also includes assessing the accounting
principles used  and significant  estimates  made by  the  Sponsor, as  well  as
evaluating  the overall  financial statement  presentation. We  believe that our
audit provides a reasonable basis for our opinion.
 
   
    In our opinion, the statement of  condition and the schedule of  investments
at  date of deposit referred to above  present fairly, in all material respects,
the financial position of Massachusetts Insured Trust 152 as of March 25,  1998,
in conformity with generally accepted accounting principles.
    
 
                                                             ARTHUR ANDERSEN LLP
 
   
Chicago, Illinois,
March 25, 1998.
    
 
                                     7 of 7
<PAGE>
   
                                 MARCH 25, 1998
                             SUBJECT TO COMPLETION
    
                                           A
   
NUVEEN                 NUVEEN NEW YORK INSURED TRUST 278
                    (NUVEEN TAX-FREE UNIT TRUST, SERIES 990)
    
                                               CUSIP NUMBERS:
   
                                               Monthly:               67102K 853
                                               Quarterly:             67102K 861
                                               Semi-Annually:         67102K 879
    
   
             PROSPECTUS--PART A (SPECIFIC TERMS) -- MARCH 25, 1998
 THIS PART A OF THE PROSPECTUS MAY NOT BE DISTRIBUTED UNLESS ACCOMPANIED BY THE
                                   PART B OF
  THE NUVEEN TAX-FREE UNIT TRUSTS PROSPECTUS DATED JULY 8, 1997, TO WHICH SUCH
                                   REFERENCE
   HEREIN APPLIES. BOTH PARTS OF THE PROSPECTUS SHOULD BE RETAINED FOR FUTURE
                                   REFERENCE.
    
 
   
    New  York  Insured  Trust  278  (the "Trust")  consists  of  a  portfolio of
interest-bearing obligations issued by  or on behalf of  the State of New  York,
certain  United  States Territories  or  authorities and  political subdivisions
thereof which,  in  the  opinion  of recognized  bond  counsel  to  the  issuing
authorities, provide income which is exempt from Federal income tax and New York
state and city income taxes, to the extent indicated below.
    
    The  objectives of the Trust are income exempt from Federal and state income
taxes, and conservation  of capital.  The objectives are,  of course,  dependent
upon  the continuing  ability of the  issuers, obligors and/or  insurers to meet
their respective obligations.
   
    The Portfolio of  the Trust  consists of  7 obligations  issued by  entities
located  in  New York  and one  obligation issued  by an  entity located  in the
Territory of Puerto Rico. The Bonds in the Trust are either general  obligations
of  the governmental  entity issuing  them and  are backed  by the  taxing power
thereof or  are payable  as  to principal  and interest  from  the income  of  a
specific  project or authority  and are not  supported by the  issuer's power to
levy taxes. The sources of payment for the Bonds are divided as follows:
    
 
   
<TABLE>
<CAPTION>
     NUMBER OF                                              PORTFOLIO
      ISSUES                PURPOSE OF ISSUE                PERCENTAGE
  ---------------  ----------------------------------------------------
  <C>              <S>                                     <C>
         2         Education Revenue                            28.5   %
         2         Dedicated-Tax Supported Revenue              22.3
         2         General Obligation                           20.6
         1         Bridge and Toll Road Revenue                 14.3
         1         Water and/or Sewer Revenue                   14.3
</TABLE>
    
 
   
    Approximately 57.1% of the  aggregate principal amount of  the Bonds in  the
Trust (accounting for approximately 55.7% of the aggregate offering price of the
Bonds)  are original issue discount obligations. Certain of these original issue
discount obligations, amounting to  5.7% of the  aggregate principal amount  and
2.3%  of  the aggregate  offering price  of the  Bonds in  the Trust,  are "zero
coupon" bonds. See "RISK FACTORS" in Part B of this Prospectus for a  discussion
of  the  characteristics  of  such  obligations  and  of  the  risks  associated
therewith.
    
    All of the Bonds in the Trust are covered by policies of insurance  obtained
from  the  MBIA  Insurance  Corporation guaranteeing  payment  of  principal and
interest when due. As a  result of such insurance, the  Bonds in the Trust  have
received  a rating of "Aaa" by Moody's, "AAA" by Fitch, and/or "AAA" by Standard
& Poor's. Insurance does not guarantee the market value of the Bonds or of Trust
Units.
   
    The Trust is  considered to be  concentrated in Bonds  of Education  Revenue
Issuers  whose  revenues  are subject  to  certain risks  including  declines in
"college age" individuals and the possible inability to raise tuition and  fees.
For  a  discussion of  the risks  associated  with investments  in the  bonds of
various issuers, see "RISK FACTORS" in Part B of this Prospectus.
    
   
                             ESSENTIAL INFORMATION
                REGARDING THE NUVEEN NEW YORK INSURED TRUST 278
        ON THE BUSINESS DAY PRIOR TO THE DATE OF DEPOSIT, MARCH 24, 1998
    
         Sponsor and Evaluator.......... John Nuveen & Co. Incorporated
         Trustee.............................. The Chase Manhattan Bank
                  -------------------------------------------
 
The income, expense and distribution data  set forth below have been  calculated
for   Unitholders  receiving  monthly,  quarterly  or  semi-annual  distribution
options.
 
   
<TABLE>
<S>                                                   <C>
Principal Amount of Bonds in Trust..................  $     1,750,000
Number of Units.....................................           17,500
Fractional Undivided Interest in Trust Per Unit.....         1/17,500
Public Offering Price--Less than 500 Units
    Aggregate Offering Price of Bonds in Trust......  $     1,700,793
    Divided by Number of Units......................  $         97.19
    Plus Sales Charge 4.9% (5.152% of the Aggregate
     Offering Price of the Bonds per Unit)..........  $          5.01
    Public Offering Price Per Unit(1)...............  $        102.20
Redemption Price Per Unit (exclusive of accrued
  interest).........................................  $         96.80
Sponsor's Initial Repurchase Price Per Unit
  (exclusive of accrued interest)...................  $         97.19
Excess of Public Offering Price Per Unit over
  Redemption Price Per Unit.........................  $          5.40
Excess of Public Offering Price Per Unit over
  Sponsor's Repurchase Price Per Unit...............  $          5.01
Average Maturity of Bonds in the Trust(2)...........       25.1 years
</TABLE>
    
 
- ----------
 
THESE SECURITIES HAVE  NOT BEEN APPROVED  OR DISAPPROVED BY  THE SECURITIES  AND
EXCHANGE  COMMISSION NOR HAS THE COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY
OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
Information  contained  herein  is  subject   to  completion  or  amendment.   A
registration  statement relating  to these  securities has  been filed  with the
Securities and Exchange  Commission. These securities  may not be  sold nor  may
offers  to buy be accepted prior to  the time the registration statement becomes
effective. This  Prospectus  shall  not  constitute an  offer  to  sell  or  the
solicitation  of an offer to buy nor shall there be any sale of these securities
in any State in which such offer,  solicitation or sale would be unlawful  prior
to registration or qualification under the securities laws of any State.
 
                                     1 of 7
<PAGE>
                         ESSENTIAL INFORMATION (CONT.)
 
   
<TABLE>
<CAPTION>
                                                  MONTHLY        QUARTERLY      SEMI-ANNUAL
                                                -----------     -----------     -----------
  <S>                                           <C>             <C>             <C>
  Calculation of Estimated Net Annual
    Interest Income Per Unit
      Annual Interest Income(3)............         $4.9407         $4.9407        $4.9407
      Less Estimated Annual Expense........          $.2583          $.2263         $.2073
                                                -----------     -----------     -----------
      Estimated Net Annual Interest
        Income(4)..........................         $4.6824         $4.7144        $4.7334
  Daily Rate of Accrual Per Unit...........         $.01300         $.01309        $.01314
  ESTIMATED CURRENT RETURN(5)..............            4.58%           4.61%          4.63 %
  ESTIMATED LONG TERM RETURN(5)............            4.58%           4.61%          4.63 %
  Trustee's Annual Fees(6).................         $1.5018         $1.1818        $0.9918
Date of Deposit.....................................................................................March 25, 1998
Settlement Date.....................................................................................March 30, 1998
Mandatory Termination Date....................................See "OTHER INFORMATION" in Part B of this Prospectus
Minimum Value of Each Trust...................................See "OTHER INFORMATION" in Part B of this Prospectus
Sponsor's Annual Evaluation Fee.........................................$0.17 per $1,000 principal amount of Bonds
Estimated Annual Organizational and Offering Expenses(7)..........................................$.02857 per Unit
- ----------
</TABLE>
    
 
The  evaluation time for purpose  of sale, purchase or  redemption of Units is 4
p.m. Eastern time or as of any earlier time at which the New York Stock Exchange
closes. (See "HOW IS THE  PUBLIC OFFERING PRICE DETERMINED?"  in Part B of  this
Prospectus.)
 
   
(1) Units  are offered at  the Public Offering Price  plus accrued interest from
    the preceding Record  Date to,  but not  including, the  date of  settlement
    (normally  three business days  after purchase). The Date  of Deposit of the
    Fund has  been  designated  as  the  First Record  Date  for  all  plans  of
    distribution  of the Trust and, accordingly, for Units purchased on the Date
    of Deposit, $.07 of accrued interest to the Settlement Date will be added to
    the Public Offering  Price. (See "WHAT  IS ACCRUED INTEREST?"  in Part B  of
    this Prospectus.)
    
 
(2) The  Average Maturity  of Bonds  in the Trust  is calculated  based upon the
    stated maturities of the Bonds in the  Trust (or, with respect to Bonds  for
    which funds or securities have been placed in escrow to redeem such Bonds on
    a  stated call  date, based  upon such call  date). The  Average Maturity of
    Bonds in the  Trust may  increase or  decrease from  time to  time as  Bonds
    mature or are called or sold.
 
(3) Assumes  delivery of  all Bonds. (See  "COMPOSITION OF  TRUSTS" appearing in
    Part B of this  Prospectus.) Interest income does  not include accretion  of
    original  issue  discount on  "zero coupon"  Bonds, Stripped  Obligations or
    other original issue discount Bonds. (See  "RISK FACTORS" in Part B of  this
    Prospectus.)
 
(4) The  amount and  timing of interest  distributions from the  Trust under the
    various plans of distribution  are set forth below.  It is anticipated  that
    the  amount of interest to  be distributed per Unit  in each year under each
    plan of distribution will initially be substantially equal to the  Estimated
    Net Annual Interest Income per Unit for that plan. The amount of interest to
    be  distributed  annually  per  Unit, will  generally  change  as  Bonds are
    redeemed, mature or are sold or as fees and expenses increase or decrease.
 
(5) Estimated Long  Term Return  for the  Trust represents  the average  of  the
    yields  to  maturity  (or  call)  of  the  Bonds  in  the  Trust's portfolio
    calculated in  accordance  with  accepted bond  practices  and  adjusted  to
    reflect  a compounding factor, expenses and sales charges. Estimated Current
    Return is computed by  dividing the Net Annual  Interest Income per Unit  by
    the  Public Offering  Price, and in  contrast to Estimated  Long Term Return
    does not reflect the  amortization of premium or  accretion of discount,  if
    any.  For  more information  see "WHAT  ARE ESTIMATED  LONG TERM  RETURN AND
    ESTIMATED CURRENT RETURN?" in Part B of this Prospectus.
 
(6) Each Trustee annual  fee is per  $1,000 principal amount  of the  underlying
    Bonds  in  the  Trust  for  that portion  of  the  Trust  that  represents a
    particular plan of distribution.
 
(7) The Trust (and  therefore Unitholders)  will bear all  or a  portion of  its
    organizational   and  offering  costs  (including  costs  of  preparing  the
    registration statements, the  trust indenture and  other closing  documents,
    registering  Units with the  Securities and Exchange  Commission and states,
    the initial audit  of the  Trust portfolio, initial  evaluation fees,  legal
    fees  and the initial fees and expenses of the Trustee but not including the
    expenses incurred in the printing of preliminary and final prospectuses, and
    expenses incurred in  the preparation  and printing of  brochures and  other
    advertising  materials  and any  other selling  expenses)  as is  common for
    mutual funds. Total organizational  expenses will be  amortized over a  five
    year  period. See "WHAT ARE  NORMAL TRUST OPERATING EXPENSES?"  in Part B of
    this Prospectus and "Statement of Condition." Historically, the sponsors  of
    unit investment trusts have paid all the costs of establishing such trusts.
 
                                     2 of 7
<PAGE>
                             INTEREST DISTRIBUTION
 
    Details  of interest distributions  per Unit of the  Trust under the various
plans appear in  the following table  based upon estimated  Net Annual  Interest
Income at the Date of Deposit:
 
   
<TABLE>
<CAPTION>
                                                                                                          NORMAL
                                                                                                      DISTRIBUTIONS
                                                         1998                          1999              PER YEAR
<S>                                     <C>            <C>            <C>            <C>            <C>
- ----------------------------------------------------------------------------------------------------  --------------
Record Date*..........................        5/1            8/1           11/1            2/1
Distribution Date.....................       5/15           8/15          11/15           2/15
- --------------------------------------------------------------------------------------------------------------------
Monthly Distribution Plan.............  $   .4680(1)                                                  $  4.6824
                                                            --------$.3900 every month--------
Quarterly Distribution Plan...........  $   .4680(1)   $  1.1781(2)   $  1.1781      $  1.1781        $  4.7144
Semi-Annual Distribution Plan.........  $   .4680(1)                  $  2.3652(3)                    $  4.7334
- --------------------------------------------------------------------------------------------------------------------
</TABLE>
    
 
 * Record  Dates for  semi-annual distributions  are May  1 and  November 1; for
   quarterly distributions, they are February 1, May 1, August 1 and November 1.
   Record Dates  for monthly  distributions are  the first  day of  each  month.
   Distribution  Dates under each distribution plan are the fifteenth day of the
   month  in  which  the  respective   Record  Date  occurred.  For   additional
   information  see "WHEN ARE  DISTRIBUTIONS MADE TO UNITHOLDERS?"  in Part B of
   this Prospectus.
 
(1) The first distribution will  be paid to all  Unitholders, regardless of  the
    distribution  plan selected.  Such distribution may  be more or  less than a
    regular monthly distribution.
 
(2) Regular 3-month distribution.
 
(3) Regular 6-month distribution.
 
                             NEW YORK RISK FACTORS
 
    The financial condition  of the  State of New  York is  affected by  various
national,   economic,   social  and   environmental  policies   and  conditions.
Additionally, Constitutional and statutory limitations imposed on the State  and
its  local governments concerning taxes, bond indebtedness and other matters may
constrain the revenue-generating capacity of the State and its local governments
and, therefore,  the  ability of  the  issuers of  the  Bonds to  satisfy  their
obligations.  Historically, the State  has been one of  the wealthiest states in
the nation; however, for  decades the State economy  has grown more slowly  than
that  of the nation as a whole,  gradually eroding the State's relative economic
affluence.
 
    The economic vitality of the State  and its various regions and,  therefore,
the  ability of the  State and its  local governments to  satisfy the Bonds, are
affected by  numerous  factors.  The  economy  of  the  State  continues  to  be
influenced  by the financial health of the City of New York, which faces greater
competition as other major cities  develop financial and business  capabilities.
The State has for many years had a very high state and local tax burden relative
to other states. The burden of State and local taxation, in combination with the
many  other  causes of  regional economic  dislocation,  has contributed  to the
decisions of some businesses and individuals to relocate outside, or not  locate
within, the State.
 
    The  State is party to numerous lawsuits  in which an adverse final decision
could materially affect the State's governmental operations and consequently its
ability to pay debt service on its  obligations. On January 21, 1994, the  State
entered  into a settlement  with Delaware with  respect to STATE  OF DELAWARE V.
STATE OF NEW YORK. The State made an immediate $35 million payment and agreed to
make a $33 million  annual payment in  each of the next  five fiscal years.  The
State  has not settled with other parties to the litigation and will continue to
incur litigation expenses as to those claims.
 
    All outstanding general  obligation bonds  of the  State are  rated "A-"  by
Standard and Poor's and "A" by Moody's.
 
    Further  information concerning New  York risk factors  may be obtained upon
written or telephonic request to the Trustee as described in "OTHER  INFORMATION
- -- Supplemental Information" appearing in Part B of this Prospectus.
 
                                   TAX STATUS
 
    For  a discussion of the Federal tax status of income earned on Trust Units,
see "WHAT IS  THE TAX  STATUS OF  UNITHOLDERS?" in  Part B  of this  Prospectus.
Investors  should be  aware that  on August  5, 1997,  the President  signed the
Taxpayer Relief Act  of 1997  (the "Act"). The  Act reduces  the maximum  stated
marginal  tax rate for capital gains for  certain investments held for more than
18 months to  20 percent (10  percent in the  case of certain  taxpayers in  the
lowest  tax bracket). The Act also  includes provisions that would treat certain
transactions designed to reduce or eliminate risk of loss and opportunities  for
gain  (e.g., short  sales, offsetting  notional principal  contracts, futures or
forward contracts, or similar transactions)  as constructive sales for  purposes
of  recognition  of gain  (and not  loss)  and for  purposes of  determining the
holding period.  Potential  investors  should consult  their  own  tax  advisors
regarding the potential effect of the Act on their investment in Units.
 
    In  the opinion of Edwards  & Angell, special counsel  for the Trust for New
York tax matters, under existing law:
 
        Interest  on  obligations  issued  by   New  York  State,  a   political
    subdivision  thereof, Puerto  Rico, the  Virgin Islands,  Guam, the Northern
    Mariana Islands,  or  other possessions  of  the United  States  within  the
    meaning of Section 103(c) of
 
                                     3 of 7
<PAGE>
    the  Internal Revenue  Code of  1986, as  amended ("New  York Obligations"),
    which would be exempt from New York  State or New York City personal  income
    tax  if  directly  received  by  a Unitholder,  will  retain  its  status as
    tax-exempt interest  when received  by  the Trust  and distributed  to  such
    Unitholder.  Thus, interest  on bonds received  by Unitholders  which is not
    subject to New York  State tax is  also exempt from  New York City  personal
    income tax.
 
        Interest  (less amortizable premium, if any) derived from the Trust by a
    resident of New  York State  (or New York  City) in  respect of  obligations
    issued  by states other than New York (or their political subdivisions) will
    be subject to New York State (or New York City) personal income tax.
 
        A Unitholder who is a resident of New York State (or New York City) will
    be subject to New  York State (or  New York City)  personal income tax  with
    respect  to gains realized when  New York Obligations held  in the Trust are
    sold, redeemed or paid at maturity  or when the Unitholder's Units are  sold
    or  redeemed;  such gain  will  equal the  proceeds  of sale,  redemption or
    payment less the tax basis of the  New York Obligation or Unit (adjusted  to
    reflect  (a) the amortization  of premium or  discount, if any,  on New York
    Obligations held by  the Trust,  (b) accrued original  issue discount,  with
    respect  to  each  New York  Obligation  which,  at the  time  the  New York
    Obligation was issued, had original issue  discount, and (c) the deposit  of
    New   York  Obligations  with  accrued  interest  in  the  Trust  after  the
    Unitholder's settlement date).
 
        Interest or gain from  the Trust derived  by a Unitholder  who is not  a
    resident  of New York  State (or New York  City) will not  be subject to New
    York State (or  New York  City) personal income  tax, unless  the Units  are
    property  employed in a business, trade, profession or occupation carried on
    in New York State (or New York City).
 
        In the case  of the  Trust, amounts  paid under  the insurance  policies
    representing maturing interest on defaulted New York Obligations held by the
    Trustee  in the Trust  will be excludable  from New York  State and New York
    City income if, and  to the same  extent as, such  interest would have  been
    excludable if paid by the respective issuer.
 
        For  purposes of the New  York State and New  York City franchise tax on
    corporations, Unitholders which are subject to such tax will be required  to
    include in their entire net income any interest or gains distributed to them
    even   though  distributed  in  respect  of  obligations  of  any  state  or
    subdivision thereof including New York.
 
        If borrowed funds are used to purchase Units in the Trust, all (or part)
    of the interest  on such indebtedness  will not be  deductible for New  York
    State  and  New  York  City  tax purposes.  The  purchase  of  Units  may be
    considered to have been made with borrowed funds even though such funds  are
    not directly traceable to the purchase of Units in the Trust.
 
                                     4 of 7
<PAGE>
   
                       NUVEEN NEW YORK INSURED TRUST 278
                    (NUVEEN TAX-FREE UNIT TRUST, SERIES 990)
         SCHEDULE OF INVESTMENTS AT THE DATE OF DEPOSIT, MARCH 25, 1998
    
 
   
<TABLE>
<CAPTION>
                                                                                          Ratings(3)           Trustee's
                                                                      Optional       ---------------------   Determination
 Aggregate        Name of Issuer and Title of Issue Represented      Redemption       Standard                of Offering
 Principal         by Sponsor's Contracts to Purchase Bonds(1)      Provisions(2)     & Poor's    Moody's        Price
<C>          <C> <S>                                              <C>                <C>         <C>        <C>
- ---------------------------------------------------------------------------------------------------------------------------
$   250,000      Dormitory Authority of the State of New York,       2007 at 101        AAA         Aaa     $       252,500
                   Rochester Institute of Technology, Insured
                   Revenue Bonds, Series 1997, 5.25% Due 7/1/22.
    250,000      Dormitory Authority of the State of New York,       2006 at 102        AAA         Aaa             257,823
                   State University Educational Facilities,
                   Revenue Bonds, Series 1996, 5.50% Due
                   5/15/26. (Original issue discount bonds
                   delivered on or about October 24, 1996 at a
                   price of 91.75% of principal amount.)
    260,000      The City of New York, New York, General             2007 at 101        AAA         Aaa             262,194
                   Obligation Bonds, Fiscal 1998 Series D, 5.25%
                   Due 8/1/21. (Original issue discount bonds
                   delivered on or about November 18, 1997 at a
                   price of 94.303% of principal amount.)
    250,000      Metropolitan Transportation Authority (New          2007 at 101        AAA         Aaa             252,078
                   York), Dedicated Tax Fund Bonds, Series
                   1996A, 5.25% Due 4/1/26. (Original issue
                   discount bonds delivered on or about October
                   29, 1996 at a price of 93.207% of principal
                   amount.)
    140,000      New York City (New York) Transitional Finance       2007 at 101        AAA         Aaa             136,829
                   Authority, Future Tax Secured Bonds, Fiscal
                   1998 Series A, 5.00% Due 8/15/27. (Original
                   issue discount bonds delivered on or about
                   October 9, 1997 at a price of 94.377% of
                   principal amount.)
    250,000      New York City (New York), Municipal Water           2007 at 101        AAA         Aaa             249,138
                   Finance Authority, Water and Sewer System
                   Revenue Bonds, Fiscal 1998 Series A, 5.125%
                   Due 6/15/21.
    250,000      Triborough Bridge and Tunnel Authority (New         2007 at 102        AAA         Aaa             251,250
                   York), General Purpose Revenue Bonds, Series
                   1996B, 5.20% Due 1/1/22.
    100,000      Commonwealth of Puerto Rico, Public Improvement  No Optional Call      AAA         Aaa              38,981
                   Refunding Bonds, Series 1998 (General
                   Obligation Bonds), 0.00% Due 7/1/17.
                   (Original issue discount bonds delivered on
                   or about January 29, 1998 at a price of
                   38.685% of principal amount.)
- -----------                                                                                                 ---------------
$ 1,750,000                                                                                                 $     1,700,793
- -----------                                                                                                 ---------------
- -----------                                                                                                 ---------------
</TABLE>
    
 
- ------------
 
    (1) The Sponsor's contracts to purchase Bonds were entered into on March 24,
1998.  Other information regarding the Bonds in the Trust on the Date of Deposit
is as follows:
 
   
<TABLE>
<CAPTION>
                                                           PROFIT (OR
                                              COST TO         LOSS)       ANNUAL INTEREST   BID PRICE
                   TRUST                      SPONSOR      TO SPONSOR     INCOME TO TRUST   OF BONDS
  ----------------------------------------  -----------  ---------------  ---------------  -----------
  <S>                                       <C>          <C>              <C>              <C>
  New York Insured Trust 278..............  $ 1,694,278  $       6,515    $    86,463      $ 1,693,943
</TABLE>
    
 
   
In addition,  the difference  between the  Trustee's determination  of  Offering
Price  and Bid Price (as a percentage of principal amount) is .39%. Neither cost
to Sponsor nor  profit (or  loss) to  Sponsor reflects  underwriting profits  or
losses  received  or  incurred  by  the  Sponsor  through  its  participation in
underwriting syndicates.  The Sponsor  did not  participate as  either the  sole
underwriter  or as a manager or member of a syndicate that acted as the original
underwriter of any of the Bonds.
    
 
    (2) The Bonds are first subject to optional redemption in the years, and  at
the  prices,  shown. Unless  otherwise indicated,  the  Bonds, except  for Bonds
issued at a  substantial original  issue discount, are  redeemable at  declining
prices  (but not below  par value) in subsequent  years. Original issue discount
bonds, including zero coupon bonds, are generally redeemable at prices based  on
the  issue  price  plus  the  amount  of  original  issue  discount  accreted to
redemption plus, if applicable, some premium,  the amount of which will  decline
in  subsequent years. The Bonds  may also be subject  to sinking fund redemption
without premium  prior to  the dates  shown.  Certain Bonds  may be  subject  to
redemption  without  premium prior  to  the date  shown  pursuant to  special or
mandatory call provisions specified in  the instruments setting forth the  terms
and  provisions of  such Bonds.  See "COMPOSITION OF  TRUSTS", "WHAT  IS THE TAX
STATUS OF UNITHOLDERS?" and "RISK FACTORS" in Part B of this Prospectus.
 
    (3) All the  Bonds in the  Insured Trusts,  as insured by  the Insurer,  are
rated  AAA  by  Standard &  Poor's,  AAA by  Fitch  and/or Aaa  by  Moody's. The
insurance obtained by the Trust guarantees the payment of interest and principal
on the Bonds when due  but does not cover  certain market risks associated  with
fixed  income  securities  such  as accelerated  payments,  premiums  payable on
mandatory redemptions or interest  rate risks. (See "WHY  AND HOW ARE THE  BONDS
INSURED?"  in Part  B of  this Prospectus  and "Description  of Ratings"  in the
Information Supplement.)
 
                                     5 of 7
<PAGE>
                             Statement of Condition
 
   
                       NUVEEN NEW YORK INSURED TRUST 278
    
 
   
                    (Nuveen Tax-Free Unit Trust, Series 990)
    
 
   
                              AS OF MARCH 25, 1998
    
 
   
<TABLE>
<S>                                                 <C>
    TRUST PROPERTY
Sponsor's contracts to purchase Bonds, backed by
  an irrevocable letter of credit(1)(2)...........  $    1,700,793
Accrued interest to March 25, 1998 on underlying
  Bonds(1)........................................          23,789
Organizational costs(3)...........................           2,500
                                                    --------------
            Total.................................  $    1,727,082
                                                    --------------
                                                    --------------
   LIABILITIES AND INTEREST OF UNITHOLDERS
LIABILITIES:
    Accrued interest to March 25, 1998 on
     underlying Bonds(4)..........................  $       23,789
    Accrued organizational and offering
     costs(3).....................................           2,500
                                                    --------------
            Total.................................  $       26,289
                                                    --------------
                                                    --------------
INTEREST OF UNITHOLDERS:
    Units of fractional undivided interest
     outstanding (17,500)
      Cost to investors(5)........................  $    1,788,418
        Less: Gross underwriting commission(6)....         (87,625)
                                                    --------------
    Net amount applicable to investors............  $    1,700,793
                                                    --------------
            Total.................................  $    1,727,082
                                                    --------------
                                                    --------------
</TABLE>
    
 
- ------------
 
(1) Represented by contracts to  purchase Bonds which  include "when issued"  or
    "regular  way"  or "delayed  delivery"  contracts for  which  an irrevocable
    letter of credit issued by a  major commercial bank has been deposited  with
    the  Trustee on the Date of Deposit. The amount of such letter of credit and
    any cash deposited  exceeds the  amount necessary  for the  purchase of  the
    Bonds  plus accrued interest to the Date of Deposit. At the Date of Deposit,
    Bonds may have been  delivered to the Sponsor  pursuant to certain of  these
    contracts;  the Sponsor has assigned to the Trustee all of its rights, title
    and interest in and to such Bonds.
 
(2) Aggregate value (at offering prices) as of the Date of Deposit of the  Bonds
    listed  under "Schedule of Investments" herein,  and their aggregate cost to
    the Trust are the  same. Such offering prices  were determined by Kenny  S&P
    Evaluation Services, a division of J. J. Kenny Co., Inc., as of the close of
    business on the business day prior to the Date of Deposit. (See "HOW WAS THE
    PRICE  OF THE BONDS  DETERMINED AT THE DATE  OF DEPOSIT?" in  Part B of this
    Prospectus.) Insurance coverage providing for the timely payment, when  due,
    of  all principal of and interest on the  Bonds in an Insured Trust has been
    obtained by the Sponsor or by the issuers of such Bonds. Such insurance does
    not guarantee the market value of the Bonds or the value of the Units.  Both
    the bid and the offering prices of the underlying Bonds and of the Units may
    include value attributable to such policies of insurance.
 
(3) The  Trust (and  therefore Unitholders)  will bear all  or a  portion of its
    estimated organizational  and  offering costs  which  will be  deferred  and
    amortized over five years from the Date of Deposit.
 
(4) Representing,  as set forth in "WHAT IS ACCRUED INTEREST?" in Part B of this
    Prospectus, advancement by  the Trustee of  an amount equal  to the  accrued
    Bond interest as of the Date of Deposit.
 
(5) Aggregate  Public Offering Price (exclusive of accrued interest) computed as
    set forth under "HOW IS THE PUBLIC OFFERING PRICE DETERMINED?" in Part B  of
    this Prospectus.
 
(6) The  gross underwriting commission of 4.90% of the Public Offering Price has
    been calculated on the assumption that the  Units sold are not subject to  a
    reduction  of sales  charge for  quantity purchases.  In single transactions
    involving 500 Units or more, the sales  charge is reduced. (See "HOW IS  THE
    PUBLIC OFFERING PRICE DETERMINED?" in Part B of this Prospectus.)
 
                                     6 of 7
<PAGE>
                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
   
TO  THE BOARD OF DIRECTORS OF JOHN  NUVEEN & CO. INCORPORATED AND UNITHOLDERS OF
NEW YORK INSURED TRUST 278:
    
 
   
    We have audited the accompanying statement of condition and the schedule  of
investments  at date of deposit  (included in Part A  of this Prospectus) of New
York Insured Trust 278 (contained in Nuveen Tax-Free Unit Trust, Series 990), as
of March 25,  1998. These  financial statements  are the  responsibility of  the
Sponsor.  Our  responsibility  is  to  express  an  opinion  on  these financial
statements based on our audit.
    
 
    We conducted  our  audit  in accordance  with  generally  accepted  auditing
standards.  Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence  supporting
the amounts and disclosures in the financial statements. Our procedures included
confirmation of the irrevocable letter of credit arrangement for the purchase of
securities,   described  in  Note   (1)  to  the   statement  of  condition,  by
correspondence with the Trustee. An audit also includes assessing the accounting
principles used  and significant  estimates  made by  the  Sponsor, as  well  as
evaluating  the overall  financial statement  presentation. We  believe that our
audit provides a reasonable basis for our opinion.
 
   
    In our opinion, the statement of  condition and the schedule of  investments
at  date of deposit referred to above  present fairly, in all material respects,
the financial position of New  York Insured Trust 278 as  of March 25, 1998,  in
conformity with generally accepted accounting principles.
    
 
                                                             ARTHUR ANDERSEN LLP
 
   
Chicago, Illinois,
March 25, 1998.
    
 
                                     7 of 7
<PAGE>
   
                                 MARCH 25, 1998
                             SUBJECT TO COMPLETION
    
                                           A
   
NUVEEN               NUVEEN PENNSYLVANIA INSURED TRUST 234
                    (NUVEEN TAX-FREE UNIT TRUST, SERIES 990)
    
                                               CUSIP NUMBERS:
   
                                               Monthly:               6706H7 466
                                               Quarterly:             6706H7 474
                                               Semi-Annually:         6706H7 482
    
   
             PROSPECTUS--PART A (SPECIFIC TERMS) -- MARCH 25, 1998
 THIS PART A OF THE PROSPECTUS MAY NOT BE DISTRIBUTED UNLESS ACCOMPANIED BY THE
                                   PART B OF
  THE NUVEEN TAX-FREE UNIT TRUSTS PROSPECTUS DATED JULY 8, 1997, TO WHICH SUCH
                                   REFERENCE
   HEREIN APPLIES. BOTH PARTS OF THE PROSPECTUS SHOULD BE RETAINED FOR FUTURE
                                   REFERENCE.
    
   
    Pennsylvania  Insured Trust  234 (the  "Trust") consists  of a  portfolio of
interest-bearing  obligations  issued  by   or  on  behalf   of  the  State   of
Pennsylvania,  certain United  States Territories  or authorities  and political
subdivisions thereof which,  in the opinion  of recognized bond  counsel to  the
issuing  authorities, provide income which is exempt from Federal income tax and
Pennsylvania state and local income taxes, to the extent indicated below.
    
    The objectives of the Trust are income exempt from Federal and state  income
taxes,  and conservation  of capital. The  objectives are,  of course, dependent
upon the continuing  ability of the  issuers, obligors and/or  insurers to  meet
their respective obligations.
   
    The  Portfolio of  the Trust  consists of  8 obligations  issued by entities
located in Pennsylvania. The Bonds in  the Trust are either general  obligations
of  the governmental  entity issuing  them and  are backed  by the  taxing power
thereof or  are payable  as  to principal  and interest  from  the income  of  a
specific  project or authority  and are not  supported by the  issuer's power to
levy taxes. The sources of payment for the Bonds are divided as follows:
    
 
   
<TABLE>
<CAPTION>
     NUMBER OF                                              PORTFOLIO
      ISSUES                PURPOSE OF ISSUE                PERCENTAGE
  ---------------  ----------------------------------------------------
  <C>              <S>                                     <C>
         3         General Obligation                           34.3   %
         2         Health Care Facility Revenue                 28.6
         2         Water and/or Sewer Revenue                   27.1
         1         Education Revenue                            10.0
</TABLE>
    
 
   
    Approximately 62.9% of the  aggregate principal amount of  the Bonds in  the
Trust (accounting for approximately 60.9% of the aggregate offering price of the
Bonds)  are original issue discount obligations. Certain of these original issue
discount obligations, amounting to  5.7% of the  aggregate principal amount  and
1.8%  of  the aggregate  offering price  of the  Bonds in  the Trust,  are "zero
coupon" bonds. See "RISK FACTORS" in Part B of this Prospectus for a  discussion
of  the  characteristics  of  such  obligations  and  of  the  risks  associated
therewith.
    
    All of the Bonds in the Trust are covered by policies of insurance  obtained
from  the  MBIA  Insurance  Corporation guaranteeing  payment  of  principal and
interest when due. As a  result of such insurance, the  Bonds in the Trust  have
received  a rating of "Aaa" by Moody's, "AAA" by Fitch, and/or "AAA" by Standard
& Poor's. Insurance does not guarantee the market value of the Bonds or of Trust
Units.
   
    The Trust is considered to be concentrated in Bonds of Health Care  Facility
Revenue  Issuers whose revenues are subject to certain risks including increased
governmental regulation, fluctuating occupancy levels and increased competition.
The Trust is also considered to be  concentrated in Bonds of Water and/or  Sewer
Revenue  Issuers whose revenues are subject  to certain risks including problems
obtaining timely and adequate rate increases and population decline resulting in
decreased user fees. For a discussion  of the risks associated with  investments
in  the  bonds  of  various  issuers,  see "RISK  FACTORS"  in  Part  B  of this
Prospectus.
    
   
                             ESSENTIAL INFORMATION
              REGARDING THE NUVEEN PENNSYLVANIA INSURED TRUST 234
       ON THE BUSINESS DAY PRIOR TO THE DATE OF DEPOSIT,  MARCH 24, 1998
    
         Sponsor and Evaluator.......... John Nuveen & Co. Incorporated
         Trustee.............................. The Chase Manhattan Bank
                  -------------------------------------------
The income, expense and distribution data  set forth below have been  calculated
for   Unitholders  receiving  monthly,  quarterly  or  semi-annual  distribution
options.
 
   
<TABLE>
<S>                                                   <C>
Principal Amount of Bonds in Trust..................  $     1,750,000
Number of Units.....................................           17,500
Fractional Undivided Interest in Trust Per Unit.....         1/17,500
Public Offering Price--Less than 500 Units
    Aggregate Offering Price of Bonds in Trust......  $     1,665,604
    Divided by Number of Units......................  $         95.18
    Plus Sales Charge 4.9% (5.152% of the Aggregate
     Offering Price of the Bonds per Unit)..........  $          4.90
    Public Offering Price Per Unit(1)...............  $        100.08
Redemption Price Per Unit (exclusive of accrued
  interest).........................................  $         94.79
Sponsor's Initial Repurchase Price Per Unit
  (exclusive of accrued interest)...................  $         95.18
Excess of Public Offering Price Per Unit over
  Redemption Price Per Unit.........................  $          5.29
Excess of Public Offering Price Per Unit over
  Sponsor's Repurchase Price Per Unit...............  $          4.90
Average Maturity of Bonds in the Trust(2)...........       27.7 years
</TABLE>
    
 
- ----------
 
THESE SECURITIES HAVE  NOT BEEN APPROVED  OR DISAPPROVED BY  THE SECURITIES  AND
EXCHANGE  COMMISSION NOR HAS THE COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY
OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
Information  contained  herein  is  subject   to  completion  or  amendment.   A
registration  statement relating  to these  securities has  been filed  with the
Securities and Exchange  Commission. These securities  may not be  sold nor  may
offers  to buy be accepted prior to  the time the registration statement becomes
effective. This  Prospectus  shall  not  constitute an  offer  to  sell  or  the
solicitation  of an offer to buy nor shall there be any sale of these securities
in any State in which such offer,  solicitation or sale would be unlawful  prior
to registration or qualification under the securities laws of any State.
 
                                     1 of 7
<PAGE>
                         ESSENTIAL INFORMATION (CONT.)
 
   
<TABLE>
<CAPTION>
                                                  MONTHLY        QUARTERLY      SEMI-ANNUAL
                                                -----------     -----------     -----------
  <S>                                           <C>             <C>             <C>
  Calculation of Estimated Net Annual
    Interest Income Per Unit
      Annual Interest Income(3)............         $4.8654         $4.8654        $4.8654
      Less Estimated Annual Expense........          $.2619          $.2299         $.2109
                                                -----------     -----------     -----------
      Estimated Net Annual Interest
        Income(4)..........................         $4.6035         $4.6355        $4.6545
  Daily Rate of Accrual Per Unit...........         $.01278         $.01287        $.01292
  ESTIMATED CURRENT RETURN(5)..............            4.60%           4.63%          4.65 %
  ESTIMATED LONG TERM RETURN(5)............            4.66%           4.69%          4.71 %
  Trustee's Annual Fees(6).................         $1.5153         $1.1953        $1.0053
Date of Deposit.....................................................................................March 25, 1998
Settlement Date.....................................................................................March 30, 1998
Mandatory Termination Date....................................See "OTHER INFORMATION" in Part B of this Prospectus
Minimum Value of Each Trust...................................See "OTHER INFORMATION" in Part B of this Prospectus
Sponsor's Annual Evaluation Fee.........................................$0.17 per $1,000 principal amount of Bonds
Estimated Annual Organizational and Offering Expenses(7)..........................................$.03085 per Unit
- ----------
</TABLE>
    
 
The  evaluation time for purpose  of sale, purchase or  redemption of Units is 4
p.m. Eastern time or as of any earlier time at which the New York Stock Exchange
closes. (See "HOW IS THE  PUBLIC OFFERING PRICE DETERMINED?"  in Part B of  this
Prospectus.)
 
   
(1) Units  are offered at  the Public Offering Price  plus accrued interest from
    the preceding Record  Date to,  but not  including, the  date of  settlement
    (normally  three business days  after purchase). The Date  of Deposit of the
    Fund has  been  designated  as  the  First Record  Date  for  all  plans  of
    distribution  of the Trust and, accordingly, for Units purchased on the Date
    of Deposit, $.06 of accrued interest to the Settlement Date will be added to
    the Public Offering  Price. (See "WHAT  IS ACCRUED INTEREST?"  in Part B  of
    this Prospectus.)
    
 
(2) The  Average Maturity  of Bonds  in the Trust  is calculated  based upon the
    stated maturities of the Bonds in the  Trust (or, with respect to Bonds  for
    which funds or securities have been placed in escrow to redeem such Bonds on
    a  stated call  date, based  upon such call  date). The  Average Maturity of
    Bonds in the  Trust may  increase or  decrease from  time to  time as  Bonds
    mature or are called or sold.
 
(3) Assumes  delivery of  all Bonds. (See  "COMPOSITION OF  TRUSTS" appearing in
    Part B of this  Prospectus.) Interest income does  not include accretion  of
    original  issue  discount on  "zero coupon"  Bonds, Stripped  Obligations or
    other original issue discount Bonds. (See  "RISK FACTORS" in Part B of  this
    Prospectus.)
 
(4) The  amount and  timing of interest  distributions from the  Trust under the
    various plans of distribution  are set forth below.  It is anticipated  that
    the  amount of interest to  be distributed per Unit  in each year under each
    plan of distribution will initially be substantially equal to the  Estimated
    Net Annual Interest Income per Unit for that plan. The amount of interest to
    be  distributed  annually  per  Unit, will  generally  change  as  Bonds are
    redeemed, mature or are sold or as fees and expenses increase or decrease.
 
(5) Estimated Long  Term Return  for the  Trust represents  the average  of  the
    yields  to  maturity  (or  call)  of  the  Bonds  in  the  Trust's portfolio
    calculated in  accordance  with  accepted bond  practices  and  adjusted  to
    reflect  a compounding factor, expenses and sales charges. Estimated Current
    Return is computed by  dividing the Net Annual  Interest Income per Unit  by
    the  Public Offering  Price, and in  contrast to Estimated  Long Term Return
    does not reflect the  amortization of premium or  accretion of discount,  if
    any.  For  more information  see "WHAT  ARE ESTIMATED  LONG TERM  RETURN AND
    ESTIMATED CURRENT RETURN?" in Part B of this Prospectus.
 
(6) Each Trustee annual  fee is per  $1,000 principal amount  of the  underlying
    Bonds  in  the  Trust  for  that portion  of  the  Trust  that  represents a
    particular plan of distribution.
 
(7) The Trust (and  therefore Unitholders)  will bear all  or a  portion of  its
    organizational   and  offering  costs  (including  costs  of  preparing  the
    registration statements, the  trust indenture and  other closing  documents,
    registering  Units with the  Securities and Exchange  Commission and states,
    the initial audit  of the  Trust portfolio, initial  evaluation fees,  legal
    fees  and the initial fees and expenses of the Trustee but not including the
    expenses incurred in the printing of preliminary and final prospectuses, and
    expenses incurred in  the preparation  and printing of  brochures and  other
    advertising  materials  and any  other selling  expenses)  as is  common for
    mutual funds. Total organizational  expenses will be  amortized over a  five
    year  period. See "WHAT ARE  NORMAL TRUST OPERATING EXPENSES?"  in Part B of
    this Prospectus and "Statement of Condition." Historically, the sponsors  of
    unit investment trusts have paid all the costs of establishing such trusts.
 
                                     2 of 7
<PAGE>
                             INTEREST DISTRIBUTION
 
    Details  of interest distributions  per Unit of the  Trust under the various
plans appear in  the following table  based upon estimated  Net Annual  Interest
Income at the Date of Deposit:
 
   
<TABLE>
<CAPTION>
                                                                                                          NORMAL
                                                                                                      DISTRIBUTIONS
                                                         1998                          1999              PER YEAR
<S>                                     <C>            <C>            <C>            <C>            <C>
- ----------------------------------------------------------------------------------------------------  --------------
Record Date*..........................        5/1            8/1           11/1            2/1
Distribution Date.....................       5/15           8/15          11/15           2/15
- --------------------------------------------------------------------------------------------------------------------
Monthly Distribution Plan.............  $   .4600(1)                                                  $  4.6035
                                                          --------  $.3834 every month  --------
Quarterly Distribution Plan...........  $   .4600(1)   $  1.1583(2)   $  1.1583      $  1.1583        $  4.6355
Semi-Annual Distribution Plan.........  $   .4600(1)                  $  2.3256(3)                    $  4.6545
- --------------------------------------------------------------------------------------------------------------------
</TABLE>
    
 
 * Record  Dates for  semi-annual distributions  are May  1 and  November 1; for
   quarterly distributions, they are February 1, May 1, August 1 and November 1.
   Record Dates  for monthly  distributions are  the first  day of  each  month.
   Distribution  Dates under each distribution plan are the fifteenth day of the
   month  in  which  the  respective   Record  Date  occurred.  For   additional
   information  see "WHEN ARE  DISTRIBUTIONS MADE TO UNITHOLDERS?"  in Part B of
   this Prospectus.
 
(1) The first distribution will  be paid to all  Unitholders, regardless of  the
    distribution  plan selected.  Such distribution may  be more or  less than a
    regular monthly distribution.
 
(2) Regular 3-month distribution.
 
(3) Regular 6-month distribution.
 
                           PENNSYLVANIA RISK FACTORS
 
    The financial condition of the  Commonwealth of Pennsylvania is affected  by
various  national, economic,  social and environmental  policies and conditions.
Additionally, Constitutional and statutory limitations imposed on the State  and
its  local governments concerning taxes, bond indebtedness and other matters may
constrain the  revenue-generating capacity  of the  Commonwealth and  its  local
governments  and, therefore, the ability of the  issuers of the Bonds to satisfy
their obligations. Historically,  the Commonwealth  has experienced  significant
revenue shortfalls.
 
    The  economic vitality of the State  and its various regions and, therefore,
the ability of the  State and its  local governments to  satisfy the Bonds,  are
affected  by numerous factors.  The economy of the  Commonwealth continues to be
dependent on heavy industry and manufacturing. These sectors tend to be cyclical
and are facing increasing competition from foreign producers.
 
    The Commonwealth is a party to  numerous lawsuits in which an adverse  final
decision  could materially affect the Commonwealth's governmental operations and
consequently its ability to pay debt service on its obligations.
 
   
    All outstanding general obligation bonds of the Commonwealth are rated
AA- by Standard and Poor's, Aa3 by Moody's and AA by Fitch IBCA, Inc.  (formerly
Fitch Investors Service).
    
 
    Further  information concerning  Pennsylvania risk  factors may  be obtained
upon written  or  telephonic request  to  the  Trustee as  described  in  "OTHER
INFORMATION -- Supplemental Information" appearing in Part B of this Prospectus.
 
                                   TAX STATUS
 
    For  a discussion of the Federal tax status of income earned on Trust Units,
see "WHAT  IS THE  TAX  STATUS OF  UNITHOLDERS?" appearing  in  Part B  of  this
Prospectus.  Investors should  be aware  that on  August 5,  1997, the President
signed the Taxpayer Relief Act of 1997 (the "Act"). The Act reduces the  maximum
stated marginal tax rate for capital gains for certain investments held for more
than 18 months to 20 percent (10 percent in the case of certain taxpayers in the
lowest  tax bracket). The Act also  includes provisions that would treat certain
transactions designed to reduce or eliminate risk of loss and opportunities  for
gain  (e.g., short  sales, offsetting  notional principal  contracts, futures or
forward contracts, or similar transactions)  as constructive sales for  purposes
of  recognition  of gain  (and not  loss)  and for  purposes of  determining the
holding period.  Potential  investors  should consult  their  own  tax  advisors
regarding the potential effect of the Act on their investment in Units.
 
    In  the opinion of  Dechert Price & Rhoads,  special Pennsylvania counsel to
the Trust, under existing law:
 
    Units evidencing fractional undivided interests in the Trust are not subject
to any of the personal property taxes presently in effect in Pennsylvania to the
extent of  that proportion  of the  Trust  represented by  Bonds issued  by  the
Commonwealth  of  Pennsylvania, its  agencies and  instrumentalities, or  by any
county, city, borough, town, township,  school district, municipality and  local
housing  or parking authority  in the Commonwealth of  Pennsylvania or issued by
Puerto  Rico,  the  Virgin  Islands,  Guam  or  the  Northern  Mariana   Islands
("Pennsylvania  Bonds"). The taxes referred to above include the County Personal
Property Tax,  the  additional personal  property  taxes imposed  on  Pittsburgh
residents  by the School District  of Pittsburgh and by  the City of Pittsburgh.
The City  of  Pittsburgh,  the  School  District  of  Pittsburgh  and  Allegheny
 
                                     3 of 7
<PAGE>
County  cannot impose personal property taxes as of January 1, 1995. Trust Units
may be taxable under the Pennsylvania inheritance and estate taxes.
 
    The  proportion  of  interest  income  representing  interest  income   from
Pennsylvania  Bonds distributed to Unitholders of the Trust is not taxable under
the Pennsylvania  Personal Income  Tax or  under the  Corporate Net  Income  Tax
imposed  on corporations  by Article IV  of the  Tax Reform Code.  Nor will such
interest be taxable under the Philadelphia School District Investment Income Tax
imposed on Philadelphia resident individuals.
 
    The disposition  by the  Trust  of a  Pennsylvania  Bond (whether  by  sale,
exchange, redemption or payment at maturity) will not constitute a taxable event
to  a Unitholder under the Pennsylvania  Personal Income Tax if the Pennsylvania
Bond was  issued  prior to  February  1, 1994.  Further,  although there  is  no
published  authority  on the  subject,  counsel is  of  the opinion  that  (i) a
Unitholder of the  Trust will not  have a taxable  event under the  Pennsylvania
state  and local income taxes referred to in the preceding paragraph (other than
the Corporate Net Income  Tax) upon the  redemption or sale of  his Unit to  the
extent  that the Trust is  then comprised of Pennsylvania  Bonds issued prior to
February 1, 1994 and (ii) the dispositions  by the Trust of a Pennsylvania  Bond
(whether  by  sale,  exchange,  redemption  or  payment  at  maturity)  will not
constitute a taxable event to a Unitholder under the Corporate Net Income Tax or
the Philadelphia School District Investment Income Tax if the Pennsylvania  Bond
was  issued  prior  to  February  1,  1994.  (The  School  District  tax  has no
application to gain on the disposition of property held by the taxpayer for more
than six months.)
 
    Gains on  the  sale, exchange,  redemption,  or  payment at  maturity  of  a
Pennsylvania Bond issued on or after February 1, 1994, will be taxable under all
of  these taxes, as will gains on the redemption or sale of a unit to the extent
that the Trust is comprised of Pennsylvania Bonds issued on or after February 1,
1994.
 
                                     4 of 7
<PAGE>
   
                     NUVEEN PENNSYLVANIA INSURED TRUST 234
                    (NUVEEN TAX-FREE UNIT TRUST, SERIES 990)
         SCHEDULE OF INVESTMENTS AT THE DATE OF DEPOSIT, MARCH 25, 1998
    
 
   
<TABLE>
<CAPTION>
                                                                                          Ratings(3)           Trustee's
                                                                      Optional       ---------------------   Determination
 Aggregate        Name of Issuer and Title of Issue Represented      Redemption       Standard                of Offering
 Principal         by Sponsor's Contracts to Purchase Bonds(1)      Provisions(2)     & Poor's    Moody's        Price
<C>          <C> <S>                                              <C>                <C>         <C>        <C>
- ---------------------------------------------------------------------------------------------------------------------------
$   250,000      Allegheny County Hospital Development Authority     2008 at 101        AAA         Aaa     $       240,503
                   (Pennsylvania), Health Center Revenue Bonds,
                   Series 1998 (Canterbury Place), 5.00% Due
                   12/1/28. (Original issue discount bonds
                   delivered on or about March 24, 1998 at a
                   price of 94.314% of principal amount.)
    225,000      The Municipal Sewer and Water Authority of          2007 at 100        AAA         Aaa             223,144
                   Cranberry Township, Butler County,
                   Pennsylvania, Sewer and Water Revenue Bonds,
                   Series 1997, 5.125% Due 12/1/26.
    175,000      Montgomery County Industrial Development            2007 at 100        AAA         Aaa             177,569
                   Authority (Pennsylvania), Revenue Bonds,
                   Series of 1997 (The Hill School Project),
                   5.35% Due 8/15/27.
    250,000      Northeastern Pennsylvania Hospital and              2007 at 102        AAA         Aaa             250,000
                   Education Authority, Health Care Revenue
                   Bonds, 1996 Series A (Wyoming Valley Health
                   Care Issue), 5.25% Due 1/1/26. (Original
                   issue discount bonds delivered on or about
                   December 19, 1996 at a price of 93.647% of
                   principal amount.)
    250,000      City of Philadelphia, Pennsylvania, Water and       2007 at 102        AAA         Aaa             243,123
                   Wastewater Revenue Bonds, Series 1997A, 5.00%
                   Due 8/1/22. (Original issue discount bonds
                   delivered on or about November 25, 1997 at a
                   price of 94.703% of principal amount.)
    100,000      Shaler Area School District (Allegheny County,   No Optional Call      AAA         Aaa              29,715
                   Pennsylvania), General Obligation Bonds,
                   Series A of 1997, 0.00% Due 11/15/21.
                   (Original issue discount bonds delivered on
                   or about December 1, 1997 at a price of
                   26.323% of principal amount.)
    250,000      The School District of the Township of Upper        2007 at 100        AAA         Aaa             250,625
                   St. Clair, Allegheny County, Pennsylvania,
                   General Obligation Bonds, Series of 1997,
                   5.20% Due 7/15/27. (Original issue discount
                   bonds delivered on or about May 1, 1997 at a
                   price of 92.701% of principal amount.)
    250,000      Wayne County Hospital and Health Facilities         2008 at 100        AAA         Aaa             250,925
                   Authority (Pennsylvania), County Guaranteed
                   Hospital Revenue Bonds, 1997 Series A (Wayne
                   Memorial Hospital Project), 5.25% Due 7/1/24.
                   (General Obligation Bonds.)
- -----------                                                                                                 ---------------
$ 1,750,000                                                                                                 $     1,665,604
- -----------                                                                                                 ---------------
- -----------                                                                                                 ---------------
</TABLE>
    
 
- ------------
 
    (1) The Sponsor's contracts to purchase  Bonds were entered into during  the
period  from March 23, 1998  to March 24, 1998.  Other information regarding the
Bonds in the Trust on the Date of Deposit is as follows:
 
   
<TABLE>
<CAPTION>
                                                           PROFIT (OR
                                              COST TO         LOSS)       ANNUAL INTEREST   BID PRICE
                   TRUST                      SPONSOR      TO SPONSOR     INCOME TO TRUST   OF BONDS
  ----------------------------------------  -----------  ---------------  ---------------  -----------
  <S>                                       <C>          <C>              <C>              <C>
  Pennsylvania Insured Trust 234..........  $ 1,661,328  $       4,276    $    85,144      $ 1,658,754
</TABLE>
    
 
   
In addition,  the difference  between the  Trustee's determination  of  Offering
Price  and Bid Price (as a percentage of principal amount) is .39%. Neither cost
to Sponsor nor  profit (or  loss) to  Sponsor reflects  underwriting profits  or
losses  received  or  incurred  by  the  Sponsor  through  its  participation in
underwriting syndicates.  The Sponsor  did not  participate as  either the  sole
underwriter  or as a manager or member of a syndicate that acted as the original
underwriter of any of the Bonds.
    
 
    (2) The Bonds are first subject to optional redemption in the years, and  at
the  prices,  shown. Unless  otherwise indicated,  the  Bonds, except  for Bonds
issued at a  substantial original  issue discount, are  redeemable at  declining
prices  (but not below  par value) in subsequent  years. Original issue discount
bonds, including zero coupon bonds, are generally redeemable at prices based  on
the  issue  price  plus  the  amount  of  original  issue  discount  accreted to
redemption plus, if applicable, some premium,  the amount of which will  decline
in  subsequent years. The Bonds  may also be subject  to sinking fund redemption
without premium  prior to  the dates  shown.  Certain Bonds  may be  subject  to
redemption  without  premium prior  to  the date  shown  pursuant to  special or
mandatory call provisions specified in  the instruments setting forth the  terms
and  provisions of  such Bonds.  See "COMPOSITION OF  TRUSTS", "WHAT  IS THE TAX
STATUS OF UNITHOLDERS?" and "RISK FACTORS" in Part B of this Prospectus.
 
    (3) All the  Bonds in the  Insured Trusts,  as insured by  the Insurer,  are
rated  AAA  by  Standard &  Poor's,  AAA by  Fitch  and/or Aaa  by  Moody's. The
insurance obtained by the Trust guarantees the payment of interest and principal
on the Bonds when due  but does not cover  certain market risks associated  with
fixed  income  securities  such  as accelerated  payments,  premiums  payable on
mandatory redemptions or interest  rate risks. (See "WHY  AND HOW ARE THE  BONDS
INSURED?"  in Part  B of  this Prospectus  and "Description  of Ratings"  in the
Information Supplement.)
 
                                     5 of 7
<PAGE>
                             Statement of Condition
 
   
                     NUVEEN PENNSYLVANIA INSURED TRUST 234
    
 
   
                    (Nuveen Tax-Free Unit Trust, Series 990)
    
 
   
                              AS OF MARCH 25, 1998
    
 
   
<TABLE>
<S>                                                 <C>
    TRUST PROPERTY
Sponsor's contracts to purchase Bonds, backed by
  an irrevocable letter of credit(1)(2)...........  $    1,665,604
Accrued interest to March 25, 1998 on underlying
  Bonds(1)........................................          22,301
Organizational costs(3)...........................           2,700
                                                    --------------
            Total.................................  $    1,690,605
                                                    --------------
                                                    --------------
   LIABILITIES AND INTEREST OF UNITHOLDERS
LIABILITIES:
    Accrued interest to March 25, 1998 on
     underlying Bonds(4)..........................  $       22,301
    Accrued organizational and offering
     costs(3).....................................           2,700
                                                    --------------
            Total.................................  $       25,001
                                                    --------------
                                                    --------------
INTEREST OF UNITHOLDERS:
    Units of fractional undivided interest
     outstanding (17,500)
      Cost to investors(5)........................  $    1,751,416
        Less: Gross underwriting commission(6)....         (85,812)
                                                    --------------
    Net amount applicable to investors............  $    1,665,604
                                                    --------------
            Total.................................  $    1,690,605
                                                    --------------
                                                    --------------
</TABLE>
    
 
- ------------
 
(1) Represented by contracts to  purchase Bonds which  include "when issued"  or
    "regular  way"  or "delayed  delivery"  contracts for  which  an irrevocable
    letter of credit issued by a  major commercial bank has been deposited  with
    the  Trustee on the Date of Deposit. The amount of such letter of credit and
    any cash deposited  exceeds the  amount necessary  for the  purchase of  the
    Bonds  plus accrued interest to the Date of Deposit. At the Date of Deposit,
    Bonds may have been  delivered to the Sponsor  pursuant to certain of  these
    contracts;  the Sponsor has assigned to the Trustee all of its rights, title
    and interest in and to such Bonds.
 
(2) Aggregate value (at offering prices) as of the Date of Deposit of the  Bonds
    listed  under "Schedule of Investments" herein,  and their aggregate cost to
    the Trust are the  same. Such offering prices  were determined by Kenny  S&P
    Evaluation Services, a division of J. J. Kenny Co., Inc., as of the close of
    business on the business day prior to the Date of Deposit. (See "HOW WAS THE
    PRICE  OF THE BONDS  DETERMINED AT THE DATE  OF DEPOSIT?" in  Part B of this
    Prospectus.) Insurance coverage providing for the timely payment, when  due,
    of  all principal of and interest on the  Bonds in an Insured Trust has been
    obtained by the Sponsor or by the issuers of such Bonds. Such insurance does
    not guarantee the market value of the Bonds or the value of the Units.  Both
    the bid and the offering prices of the underlying Bonds and of the Units may
    include value attributable to such policies of insurance.
 
(3) The  Trust (and  therefore Unitholders)  will bear all  or a  portion of its
    estimated organizational  and  offering costs  which  will be  deferred  and
    amortized over five years from the Date of Deposit.
 
(4) Representing,  as set forth in "WHAT IS ACCRUED INTEREST?" in Part B of this
    Prospectus, advancement by  the Trustee of  an amount equal  to the  accrued
    Bond interest as of the Date of Deposit.
 
(5) Aggregate  Public Offering Price (exclusive of accrued interest) computed as
    set forth under "HOW IS THE PUBLIC OFFERING PRICE DETERMINED?" in Part B  of
    this Prospectus.
 
(6) The  gross underwriting commission of 4.90% of the Public Offering Price has
    been calculated on the assumption that the  Units sold are not subject to  a
    reduction  of sales  charge for  quantity purchases.  In single transactions
    involving 500 Units or more, the sales  charge is reduced. (See "HOW IS  THE
    PUBLIC OFFERING PRICE DETERMINED?" in Part B of this Prospectus.)
 
                                     6 of 7
<PAGE>
                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
   
TO  THE BOARD OF DIRECTORS OF JOHN  NUVEEN & CO. INCORPORATED AND UNITHOLDERS OF
PENNSYLVANIA INSURED TRUST 234:
    
 
   
    We have audited the accompanying statement of condition and the schedule  of
investments  at  date of  deposit (included  in  Part A  of this  Prospectus) of
Pennsylvania Insured Trust 234 (contained in Nuveen Tax-Free Unit Trust,  Series
990), as of March 25, 1998. These financial statements are the responsibility of
the  Sponsor. Our  responsibility is  to express  an opinion  on these financial
statements based on our audit.
    
 
    We conducted  our  audit  in accordance  with  generally  accepted  auditing
standards.  Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence  supporting
the amounts and disclosures in the financial statements. Our procedures included
confirmation of the irrevocable letter of credit arrangement for the purchase of
securities,   described  in  Note   (1)  to  the   statement  of  condition,  by
correspondence with the Trustee. An audit also includes assessing the accounting
principles used  and significant  estimates  made by  the  Sponsor, as  well  as
evaluating  the overall  financial statement  presentation. We  believe that our
audit provides a reasonable basis for our opinion.
 
   
    In our opinion, the statement of  condition and the schedule of  investments
at  date of deposit referred to above  present fairly, in all material respects,
the financial position of Pennsylvania Insured  Trust 234 as of March 25,  1998,
in conformity with generally accepted accounting principles.
    
 
                                                             ARTHUR ANDERSEN LLP
 
   
Chicago, Illinois,
March 25, 1998.
    
 
                                     7 of 7
<PAGE>

<PAGE>
                                           B
 
NUVEEN  Tax-Free Unit Trusts
             PROSPECTUS -- PART B
            (GENERAL TERMS)
   
              JULY 8, 1997
    
 
THIS  PART B OF THE PROSPECTUS MAY NOT BE DISTRIBUTED UNLESS ACCOMPANIED BY PART
A. BOTH PARTS OF THIS PROSPECTUS SHOULD BE RETAINED FOR FUTURE REFERENCE.
   
FURTHER DETAIL REGARDING CERTAIN OF  THE INFORMATION PROVIDED IN THE  PROSPECTUS
MAY  BE OBTAINED WITHIN FIVE  BUSINESS DAYS OF WRITTEN  OR TELEPHONIC REQUEST TO
THE TRUSTEE AT 4 NEW YORK PLAZA, NEW YORK, NY 10004-2413 OR (800) 257-8787.
    
INTEREST INCOME TO A TRUST AND TO UNITHOLDERS, IN THE OPINION OF COUNSEL,  UNDER
EXISTING  LAW IS  EXEMPT FROM  FEDERAL INCOME  TAX. CAPITAL  GAINS, IF  ANY, ARE
SUBJECT TO TAX. IN ADDITION, INTEREST INCOME OF STATE TRUSTS IS, IN THE  OPINION
OF  COUNSEL,  EXEMPT,  TO THE  EXTENT  INDICATED,  FROM STATE  AND  LOCAL TAXES.
INTEREST INCOME OF ANY TRUST  OTHER THAN A STATE TRUST  MAY BE SUBJECT TO  STATE
AND LOCAL TAXES.
 
CURRENTLY  OFFERED AT PUBLIC OFFERING PRICE PLUS INTEREST ACCRUED TO THE DATE OF
SETTLEMENT. MINIMUM PURCHASE--EITHER $5,000 OR 50 UNITS, WHICHEVER IS LESS.
 
   
THIS NUVEEN TAX-FREE UNIT TRUST SERIES consists of the underlying separate  unit
investment  trusts set forth in Part A  to this Prospectus. Each Trust initially
consists of delivery  statements relating  to contracts to  purchase Bonds  and,
thereafter,  will consist of a diversified portfolio of obligations issued by or
on behalf of  states and territories  of the United  States and authorities  and
political  subdivisions thereof (see "Schedule of Investments" appearing in Part
A of this Prospectus). Except in specific  instances as noted in Part A of  this
Prospectus,  the information contained in this Part  B shall apply to each Trust
in its entirety.  All obligations  in each Traditional  Trust are  rated in  the
category  "A" or  better by  Standard &  Poor's, a  division of  The McGraw Hill
Companies ("Standard & Poor's"), Moody's Investors Service, Inc. ("Moody's")  or
Fitch  Investors Service, Inc. ("Fitch") on the Date of Deposit. All obligations
in each Insured  Trust are covered  by policies of  insurance obtained from  the
MBIA  Insurance Corporation guaranteeing payment  of principal and interest when
due. All such policies of insurance remain effective so long as the  obligations
are  outstanding. As a result of such  insurance, the Bonds in each portfolio of
the Insured Trusts have received  a rating of "Aaa"  by Moody's, "AAA" by  Fitch
and/  or "AAA" by Standard & Poor's. INSURANCE  RELATES ONLY TO THE BONDS IN THE
INSURED TRUSTS AND NOT  TO THE UNITS  OFFERED HEREBY OR  TO THEIR MARKET  VALUE.
(See "WHY AND HOW ARE THE BONDS INSURED?")
    
 
   
THE  OBJECTIVES of  a Trust  are tax-exempt  income and  conservation of capital
through a diversified investment  in tax-exempt Bonds.  The payment of  interest
and  the preservation of principal are, of course, dependent upon the continuing
ability of  the issuers  of  Bonds and  of any  insurer  thereof to  meet  their
obligations  thereunder. There is no guarantee that a Trust's objectives will be
achieved. (See "RISK FACTORS.")
    
 
DISTRIBUTIONS of interest received by a Trust will be made semi-annually  unless
the  Unitholder  elects to  receive them  monthly or  quarterly. (See  "WHEN ARE
DISTRIBUTIONS MADE  TO UNITHOLDERS?")  Distribution of  funds in  the  Principal
Account, if any, will ordinarily be made semi-annually.
 
   
FOR  ESTIMATED LONG TERM RETURNS AND ESTIMATED CURRENT RETURNS to Unitholders on
the business day prior to the Date of Deposit, see Part A of this Prospectus and
"WHAT ARE ESTIMATED LONG TERM RETURN AND ESTIMATED CURRENT RETURN?"
    
 
   
THE PUBLIC OFFERING  PRICE per Unit  of each Trust  during the initial  offering
period  is equal to a pro rata share of the OFFERING prices of the Bonds in such
Trust's portfolio plus  a sales charge  of up  to 4.90% of  the Public  Offering
Price  (equivalent to 5.152%  of the net  amount invested); the  sales charge is
somewhat lower on Trusts with lesser average maturities. (See "HOW IS THE PUBLIC
OFFERING PRICE DETERMINED?") The Secondary Market Public Offering Price per Unit
for each Trust will be equal to a pro rata share of the sum of BID prices of the
Bonds in such Trust  plus the sales  charges determined based  on the number  of
years  remaining  to  the  maturity  of each  Bond.  Accrued  interest  from the
preceding Record Date to, but not including, the settlement date (normally three
business days after purchase) is added  to the Public Offering Price. The  sales
charge  is reduced on a graduated scale  for sales involving at least $50,000 or
500 Units  and will  be applied  on whichever  basis is  more favorable  to  the
purchaser. (See "HOW IS THE PUBLIC OFFERING PRICE DETERMINED?")
    
 
   
A  UNITHOLDER MAY REDEEM UNITS at the office of the Trustee at prices based upon
the BID prices of the Bonds. The  price received upon redemption may be more  or
less  than the amount paid by Unitholders, depending upon the value of the Bonds
on the date of tender  for redemption. (See "HOW  UNITS MAY BE REDEEMED  WITHOUT
CHARGE.")  The  Sponsor, although  not  required to  do  so, intends  to  make a
secondary market for the Units of the Trusts at prices based upon the BID prices
of the Bonds in the respective Trusts. (See "MARKET FOR UNITS.")
    
 
RISK FACTORS. An investment in a Trust  should be made with an understanding  of
the risks associated therewith, including, among other factors, the inability of
the issuer or an insurer to pay the principal of or interest on a Bond when due,
volatile interest rates, early call provisions, and changes to the tax status of
the Bonds. See Part A of this Prospectus and "RISK FACTORS."
 
UNITS OF THE TRUST ARE NOT DEPOSITS OR OBLIGATIONS OF, OR GUARANTEED OR ENDORSED
BY, ANY BANK AND ARE NOT FEDERALLY INSURED OR OTHERWISE PROTECTED BY THE FEDERAL
DEPOSIT INSURANCE CORPORATION, THE FEDERAL RESERVE BOARD OR ANY OTHER AGENCY AND
INVOLVE INVESTMENT RISK, INCLUDING THE POSSIBLE LOSS OF PRINCIPAL.
 
THESE  SECURITIES HAVE  NOT BEEN APPROVED  OR DISAPPROVED BY  THE SECURITIES AND
EXCHANGE
COMMISSION OR  ANY  STATE  SECURITIES  COMMISSION NOR  HAS  THE  SECURITIES  AND
EXCHANGE
COMMISSION  OR  ANY  STATE SECURITIES  COMMISSION  PASSED UPON  THE  ACCURACY OR
ADEQUACY OF
THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>
  NUVEEN  Tax-Free Unit Trusts
 
   
<TABLE>
<CAPTION>
      TABLE OF CONTENTS                                  PAGE
<C>   <S>                                                <C>
      WHAT IS THE NUVEEN TAX-FREE UNIT TRUST?            4
      WHAT ARE THE OBJECTIVES OF THE TRUSTS?             4
      SUMMARY OF PORTFOLIOS                              4
      RISK FACTORS                                       5
      COMPOSITION OF TRUSTS                              6
      WHY AND HOW ARE THE BONDS INSURED?                 8
      HOW IS THE PUBLIC OFFERING PRICE DETERMINED?       9
      MARKET FOR UNITS                                   11
      WHAT IS ACCRUED INTEREST?                          12
      WHAT ARE ESTIMATED LONG TERM RETURN AND ESTIMATED
      CURRENT RETURN?                                    12
      HOW WAS THE PRICE OF THE BONDS DETERMINED AT THE
      DATE
      OF DEPOSIT?                                        13
      WHAT IS THE TAX STATUS OF UNITHOLDERS?             13
      WHAT ARE NORMAL TRUST OPERATING EXPENSES?          15
      WHEN ARE DISTRIBUTIONS MADE TO UNITHOLDERS?        16
      ACCUMULATION PLAN                                  17
      HOW DETAILED ARE REPORTS TO UNITHOLDERS?           17
      UNIT VALUE AND EVALUATION                          17
      HOW UNITS OF THE TRUSTS ARE DISTRIBUTED TO THE
      PUBLIC                                             18
      OWNERSHIP AND TRANSFER OF UNITS                    19
      HOW UNITS MAY BE REDEEMED WITHOUT CHARGE           20
      HOW UNITS MAY BE PURCHASED BY THE SPONSOR          21
      HOW BONDS MAY BE REMOVED FROM THE TRUSTS           21
      INFORMATION ABOUT THE TRUSTEE                      21
      INFORMATION ABOUT THE SPONSOR                      22
      OTHER INFORMATION                                  22
</TABLE>
    
 
                  2
<PAGE>
  NUVEEN  Tax-Free Unit Trusts
 
   
<TABLE>
<CAPTION>
      TOPICAL INDEX                                              PAGE
<C>   <S>                                               <C>      <C>
      Accrued Interest                                           12
      Accumulation Plan                                          17
                                                           Information
      Bond Ratings, Description of                         Supplement
      Bonds, Initial Determination of Offering Price             13
      Bonds, How Selected                                        4
      Bonds, Limited Right of Substitution                       7
      Bonds, Removal from a Trust                                21
      Call Provisions of Portfolio Bonds                         7
      Capital Gains Taxability                                   14
      Composition of Trusts                                      7
      Dealer Discounts                                           18
      Distributions to Unitholders                               16
                                                                 Part
      Distribution Payment Dates                                 A,16
      Distribution of Units to the Public                        18
                                                                 Part
      Essential Information Regarding the Trusts                 A,12
                                                                 Part
      Estimated Long Term Return and Estimated Current Return    A,12
      Evaluation                                                 17
      Expenses for Normal Trust Operation                        15
      Indenture, Amendment of                                    22
      Indenture, Termination of                                  22
      Insurance on the Bonds                                     8
      Interest Account Distributions                             Part A
      Legal Opinion                                              23
      Limitations on Liabilities of Sponsor and Trustee          21
      Market for Units                                           11
      Minimum Transaction                                        18
      Objectives of the Trusts                                   4
      Optional Distribution Plan                                 16
      Other Information                                          22
      Ownership and Transfer of Units                            19
      Principal Account Distributions                            16
      Public Offering Price of Units                             9
      Purchase of Units by Sponsor                               21
      Quantity Purchases                                         9
                                                                 Part
      Record Dates                                               A,16
      Redemption of Units Without Charge                         20
      Report of Independent Public Accountants                   Part A
      Reports to Unitholders                                     17
      Risk Factors                                               5
      Sales Charge                                               10
      Schedules of Investments                                   Part A
      Sponsor, Information About                                 22
      State Tax Status                                           Part A
      Statements of Condition                                    Part A
      Successor Trustees and Sponsors                            22
      Supplemental Information                                   23
      Tax Status of Unitholders                                  13
      Trustee, Information About                                 21
      Units, Description of                                      4
</TABLE>
    
 
                  3
<PAGE>
WHAT IS THE NUVEEN TAX-FREE UNIT TRUST?
 
   
This Nuveen Tax-Free  Unit Trust  is one  of a  series of  separate but  similar
investment  companies created by the  Sponsor, each of which  is designated by a
different Series number. The underlying unit investment trusts contained in this
Series  are  combined  under  one   Trust  Indenture  and  Agreement.   Specific
information  regarding this Trust is set forth in Part A of this Prospectus. The
various Nuveen Tax-Free Unit Trusts are  collectively referred to herein as  the
"Trusts"; the trusts in which few or none of the Bonds are insured are sometimes
referred  to as the "Traditional  Trusts," the trusts in  which all of the Bonds
are insured  as described  herein  are sometimes  referred  to as  the  "Insured
Trusts,"  and  the state  trusts (both  Traditional  and Insured)  are sometimes
referred to as the "State Trusts." This Series was created under the laws of the
State of New York pursuant to a Trust Indenture and Agreement dated the Date  of
Deposit  (the "Indenture") between  John Nuveen &  Co. Incorporated ("Nuveen" or
the "Sponsor") and The Chase Manhattan Bank (the "Trustee").
    
 
   
    The Sponsor has deposited with  the Trustee delivery statements relating  to
contracts  for the  purchase of municipal  debt obligations  together with funds
represented by an irrevocable letter of credit issued by a major commercial bank
in the amount, including accrued interest,  required for their purchase (or  the
obligations  themselves) (the "Bonds"). See "Schedule  of Investments" in Part A
of this Prospectus, for  a description of  the Bonds deposited  in a Trust.  See
"SUMMARY OF PORTFOLIOS" and "RISK FACTORS" for a discussion of zero coupon bonds
and  stripped obligations included in  the Trusts, if any.  Some of the delivery
statements may relate to  contracts for the purchase  of "when issued" or  other
Bonds  with delivery dates after  the date of settlement  for a purchase made on
the Date  of Deposit.  See  the "Schedule  of Investments"  in  Part A  of  this
Prospectus  and  "COMPOSITION  OF TRUSTS."  For  a discussion  of  the Sponsor's
obligations in the event of a failure of any contract for the purchase of any of
the Bonds and its limited right to substitute other bonds to replace any  failed
contract, see "COMPOSITION OF TRUSTS."
    
 
   
    Payment  of interest on the Bonds in each Insured Trust, and of principal at
maturity, is guaranteed under policies of  insurance obtained by the Sponsor  or
by  the issuers of  the Bonds. (See "WHY  AND HOW ARE THE  BONDS INSURED?") AS A
GENERAL MATTER, NEITHER THE ISSUER NOR  THE SPONSOR HAS OBTAINED INSURANCE  WITH
RESPECT TO THE BONDS IN ANY TRADITIONAL TRUST.
    
 
    The  Trustee has delivered  to the Sponsor  registered Units which represent
ownership of  the  entire  Trust,  and  which  are  offered  for  sale  by  this
Prospectus.  Each Unit of a Trust  represents a fractional undivided interest in
the principal and net income of such Trust in the ratio set forth in  "Essential
Information"  in Part A of this Prospectus. Units  may only be sold in states in
which they  are registered.  To  the extent  that any  Units  of any  Trust  are
redeemed by the Trustee, the aggregate value of the Trust's assets will decrease
by  the amount  paid to the  redeeming Unitholder, but  the fractional undivided
interest of each unredeemed  Unit in such  Trust will increase  proportionately.
The  Sponsor will  initially, and  from time to  time thereafter,  hold Units in
connection with their offering.
 
WHAT ARE THE OBJECTIVES OF THE TRUSTS?
 
   
The objectives of the Trusts are income  exempt from Federal income tax and,  in
the  case of State Trusts, where applicable, state income and intangibles taxes,
and conservation of capital, through an  investment in obligations issued by  or
on  behalf of states  and territories of  the United States  and authorities and
political subdivisions thereof,  the interest  on which  is, in  the opinion  of
recognized  bond counsel  to the  issuing governmental  authorities, exempt from
Federal income tax under existing law  and for State Trusts, from certain  state
income  taxes  and intangibles  taxes,  if any,  for  purchasers who  qualify as
residents of that State  in which Bonds are  issued. Insurance guaranteeing  the
timely  payment, when due,  of all principal  and interest on  the Bonds in each
Insured Trust has been obtained by the  Sponsor or by the issuers of such  Bonds
from  MBIA Insurance Corporation, and as a result of such insurance the Bonds in
the Insured Trusts are rated  "Aaa" by Moody's, "AAA"  by Fitch and/or "AAA"  by
Standard & Poor's. (See "WHY AND HOW ARE THE BONDS INSURED?") All obligations in
each  Traditional Trust are rated in the category  "A" or better (SP-1, MIG 2 or
F-2 or better, respectively, in the case of short term obligations included in a
Short Term  Traditional  Trust)  by  Standard &  Poor's,  Moody's  and/or  Fitch
(including  provisional or conditional  ratings). In addition,  certain Bonds in
certain Traditional Trusts may be  covered by insurance guaranteeing the  timely
payment,  when  due, of  all principal  and  interest. There  is, of  course, no
guarantee that the Trusts' objectives will be achieved. For a comparison of  net
after-tax return for various tax brackets, see the "TAXABLE EQUIVALENT ESTIMATED
CURRENT  RETURN TABLES" included in the Appendices to the Information Supplement
of this Prospectus.
    
 
SUMMARY OF PORTFOLIOS
 
   
In selecting  Bonds for  the  respective Trusts,  the following  factors,  among
others, were considered: (i) the Standard & Poor's, Moody's and/or Fitch ratings
of  the Bonds (see "WHAT ARE THE OBJECTIVES OF THE TRUSTS?" for a description of
minimum rating standards), (ii) the prices of the Bonds relative to other  bonds
of  comparable quality  and maturity, (iii)  the diversification of  Bonds as to
purpose of issue and location of issuer,  (iv) the maturity dates of the  Bonds,
and  (v)  in the  case  of the  Insured Trusts  only,  the availability  of MBIA
Insurance Corporation insurance on such Bonds.  (See "WHY AND HOW ARE THE  BONDS
INSURED?")
    
 
                                       4
<PAGE>
RISK FACTORS
 
   
An  investment in Units of any Trust should be made with an understanding of the
risks that such  an investment  may entail.  Each Trust  consists of  fixed-rate
municipal  debt  obligations. As  such, the  value of  the debt  obligations and
therefore of  the  Units will  decline  with  increases in  interest  rates.  In
general,  the longer the period until the maturity of a Bond, the more sensitive
its value will be to fluctuations in interest rates. The Sponsor cannot  predict
the  extent or timing  of such fluctuations and,  accordingly, their effect upon
the value  of the  Bonds. Additional  risk factors  include the  ability of  the
issuer,  or,  if  applicable,  an  insurer, to  make  payments  of  interest and
principal when  due, "mandatory  put" features,  early call  provisions and  the
potential  for changes in the tax status of the Bonds. As set forth in Part A of
this Prospectus, the Trusts may contain or be concentrated in one or more of the
types of bonds discussed below. The following paragraphs briefly discuss certain
circumstances which may adversely affect the ability of issuers of Bonds held in
the portfolio of a Trust to make payments of principal and interest thereon, and
which also  therefore may  adversely  affect the  ratings  of such  Bonds.  With
respect  to Insured  Trusts, however, because  of the insurance  obtained by the
Sponsor or by the issuers of the Bonds, such changes should not adversely affect
an Insured Trust's receipt  of principal and interest  or the Standard &  Poor's
"AAA",  the Moody's "Aaa" or the Fitch "AAA" ratings of the Bonds in the Insured
Trust portfolio.  The  Bonds  described  below may  be  subject  to  special  or
extraordinary   redemption  provisions.  For  economic  risks  specific  to  the
individual Trusts,  see Part  A of  this Prospectus  and the  Appendices to  the
Information Supplement of this Prospectus.
    
 
   
    ESCROW  SECURED OBLIGATIONS are  typically secured by  direct obligations of
the U.S.  Government  or  in  some cases  obligations  guaranteed  by  the  U.S.
Government  placed in  an escrow  account maintained  by an  independent trustee
until maturity  or  a  predetermined  redemption  date.  These  obligations  are
generally noncallable prior to maturity or the predetermined redemption date. In
a  few isolated instances, however,  bonds which were thought  to be escrowed to
maturity have been called for redemption prior to maturity.
    
 
   
    HEALTH CARE FACILITY OBLIGATIONS are  obligations of issuers whose  revenues
are derived from services provided by hospitals or other health care facilities,
including  nursing  homes. The  ability  of such  issuers  to make  debt service
payments on  these  obligations  is  dependent  on  various  factors,  including
occupancy  levels  of the  facility, demand  for  services, wages  of employees,
overhead  expenses,  competition  from   other  similar  providers,   government
regulation,  the cost of  malpractice insurance, and  the degree of governmental
financial assistance, including Medicare and Medicaid.
    
 
    HOUSING OBLIGATIONS are obligations of issuers whose revenues are  primarily
derived  from mortgage loans on single family residences or housing projects for
low to moderate income families. Housing obligations are generally prepayable at
any time and  therefore their average  life will ordinarily  be less than  their
stated  maturities. The ability of such issuers to make debt service payments on
these obligations is dependent on  various factors, including occupancy  levels,
rental  income, mortgage default rates,  taxes, operating expenses, governmental
regulations and the appropriation of subsidies.
 
    INDUSTRIAL  REVENUE  OBLIGATIONS  are  industrial  revenue  bonds  ("IRBs"),
including  pollution  control  revenue bonds,  which  are  tax-exempt securities
issued by  states, municipalities,  public authorities  or similar  entities  to
finance  the  cost of  acquiring, constructing  or improving  various industrial
projects. Debt  service  payment on  IRBs  is dependent  upon  various  factors,
including  the creditworthiness of the corporate operator of the project and, if
applicable, corporate guarantor, revenues  generated from the project,  expenses
associated with the project and regulatory and environmental restrictions.
 
   
    UTILITY  OBLIGATIONS are obligations of issuers whose revenues are primarily
derived from the sale of several types of energy, including electric and natural
gas. The  ability  of  such issuers  to  make  debt service  payments  on  these
obligations is dependent on various factors, including the rates for electricity
and  natural gas,  the demand  for electricity  and natural  gas, the  degree of
competition, governmental regulation, overhead expenses and variable costs, such
as fuel.
    
 
    TRANSPORTATION FACILITY REVENUE OBLIGATIONS are obligations of issuers which
are payable  from  and  secured  by revenues  derived  from  the  ownership  and
operation  of airports, public transit systems and ports. The ability of issuers
to make  debt  service payments  on  airport  obligations is  dependent  on  the
capability  of airlines to  meet their obligations under  use agreements. Due to
increased competition,  deregulation, increased  fuel costs  and other  factors,
many  airlines may  have difficulty  meeting their  obligations under  these use
agreements. Bonds  that are  secured primarily  by the  revenue collected  by  a
public  transit system typically  are additionally secured by  a pledge of sales
tax receipts collected  at the state  or local level,  or of other  governmental
financial  assistance. The revenue of issuers of transit system obligations will
be affected by variations in utilization, which  in turn may be affected by  the
degree  of  local governmental  subsidization, competition  from other  forms of
transportation, and  increased costs.  Port  authorities derive  their  revenues
primarily  from fees imposed  on ships using the  facilities which may fluctuate
depending on  the local  economy  and on  competition  from competing  forms  of
transportation  such  as air,  rail and  trucks. The  revenues of  issuers which
derive their  payments  from bridge,  road  or  tunnel toll  revenues  could  be
adversely  affected  by  increases  in fuel  costs,  competition  from toll-free
vehicular bridges and roads and alternative modes of transportation.
 
   
    WATER AND/OR SEWERAGE OBLIGATIONS are obligations of issuers whose  revenues
are  payable from user fees from the sale of water and/or sewerage services. The
problems  of  such  issuers  include  the  ability  to  obtain  rate  increases,
population  declines,  the limitations  on  operations and  increased  costs and
delays attributable to environmental considerations, the difficulties  obtaining
new supplies of fresh water, the effect of conservation programs and "no-growth"
zoning ordinances.
    
 
                                       5
<PAGE>
    UNIVERSITY  AND COLLEGE REVENUE OBLIGATIONS are obligations of issuers whose
revenues are  derived  mainly  from  tuition,  dormitory  revenues,  grants  and
endowments.  General  problems faced  by such  issuers  include declines  in the
number of "college" age  individuals, possible inability  to raise tuitions  and
fees,  the uncertainty of continued receipt of Federal grants and state funding,
and government  legislation  or  regulations  which  may  adversely  affect  the
revenues or costs of such issuers.
 
    DEDICATED-TAX  SUPPORTED OBLIGATIONS  are obligations  of issuers  which are
payable from  and  secured by  tax  revenues  from a  designated  source,  which
revenues  are pledged to secure the bonds.  The various types of Bonds described
below differ in structure and with respect  to the rights of the bondholders  to
the  underlying property. Each type of dedicated-tax supported Bond has distinct
risks, only  some  of which  are  set forth  below.  One type  of  dedicated-tax
supported  Bond  is  secured by  the  incremental  tax received  on  either real
property or on sales within a  specifically defined geographical area; such  tax
generally will not provide bondholders with a lien on the underlying property or
revenues.  Another type of dedicated-tax supported  Bond is secured by a special
tax levied on real property within a defined geographical area in such a  manner
that  the  tax is  levied  on those  who benefit  from  the project;  such bonds
typically provide for  a statutory lien  on the underlying  property for  unpaid
taxes.  A third  type of dedicated-tax  supported Bond  may be secured  by a tax
levied upon the  manufacture, sale  or consumption  of commodities  or upon  the
license  to pursue  certain occupations  or upon  corporate privileges  within a
taxing jurisdiction. As  to any  of these  types of  Bonds, the  ability of  the
designated revenues to satisfy the interest and principal payments on such bonds
may  be affected by changes  in the local economy,  the financial success of the
enterprise responsible for the payment of  the taxes, the value of any  property
on which taxes may be assessed and the ability to collect such taxes in a timely
fashion.  Each of these  factors will have  a different affect  on each distinct
type of dedicated-tax supported bonds.
 
    MUNICIPAL LEASE  OBLIGATIONS  are  obligations that  are  secured  by  lease
payments  of a  governmental entity  and are  normally subject  to annual budget
appropriations of the  leasing governmental entity.  A governmental entity  that
enters  into  such  a  lease agreement  cannot  obligate  future  governments to
appropriate for and make lease payments but covenants to take such action as  is
necessary  to include  any lease  payments due  in its  budgets and  to make the
appropriations therefor. A governmental entity's failure to appropriate for  and
to  make payments under its lease  obligation could result in insufficient funds
available for payment of the obligations secured thereby.
 
    ORIGINAL ISSUE DISCOUNT OBLIGATIONS AND STRIPPED OBLIGATIONS are bonds which
were issued with  nominal interest  rates less than  the rates  then offered  by
comparable  securities and as  a consequence were originally  sold at a discount
from their face,  or par,  values. In a  stable interest  rate environment,  the
market  value of  an original  issue discount bond  would tend  to increase more
slowly in early years and in greater increments as the bond approached maturity.
 
    Certain of the original  issue discount obligations in  a Trust may be  zero
coupon  bonds. Zero coupon bonds  do not provide for  the payment of any current
interest; the buyer receives only  the right to receive  a final payment of  the
face  amount  of the  bond at  its maturity.  Zero coupon  bonds are  subject to
substantially greater  price  fluctuations  during periods  of  changing  market
interest  rates  than are  securities of  comparable  quality that  pay interest
currently.
 
    Original issue discount  obligations, including  zero coupon  bonds, may  be
subject  to redemption  at prices based  on the  issue price plus  the amount of
original issue discount accreted to  redemption (the "accreted value") plus,  if
applicable,  some premium. Pursuant  to such call  provisions, an original issue
discount bond may be called prior to its maturity date at a price less than  its
face  value.  See the  "Schedule of  Investments"  appearing in  Part A  of this
Prospectus for more information about the call provisions of portfolio Bonds.
 
    Certain of the Bonds in a Trust may be stripped obligations, which represent
evidences of  ownership with  respect to  either the  principal amount  of or  a
payment  of interest on  a tax-exempt obligation  ("Stripped Obligations"). Each
Stripped Obligation has been purchased at a discount from the amount payable  at
maturity.  A Stripped Obligation therefore  has economic characteristics similar
to zero coupon bonds, as described above.
 
    Unitholders should consult their own tax advisers with respect to the  state
and  local tax consequences of owning  original issue discount bonds or Stripped
Obligations. Under applicable  provisions governing determination  of state  and
local  taxes,  interest  on  original  issue  discount  obligations  or Stripped
Obligations may be  deemed to be  received in  the year of  accrual even  though
there is no corresponding cash payment.
 
    Certain  bonds may carry a "mandatory put" (also referred to as a "mandatory
tender" or "mandatory repurchase") feature pursuant to which the holder of  such
bonds will receive payment of the full principal amount thereof on a stated date
prior  to the maturity date unless such  holder affirmatively acts to retain the
bond. The Trustee does not have the  authority to act to retain Bonds with  such
features;  accordingly, it will receive payment  of the full principal amount of
any such Bonds on the stated put date and such date is therefore treated as  the
maturity date of such Bonds in selecting Bonds for the respective Trusts and for
purposes of calculating the average maturity of the Bonds in any Trust.
 
COMPOSITION OF TRUSTS
 
Each  Trust initially consists  of delivery statements  relating to contracts to
purchase Bonds (or of such Bonds) as are listed under "Schedule of  Investments"
in  Part A of this Prospectus and, thereafter,  of such Bonds as may continue to
be held from time to time  (including certain securities deposited in the  Trust
in    substitution   for    Bonds   not   delivered    to   a    Trust   or   in
 
                                       6
<PAGE>
exchange or  substitution  for Bonds  upon  certain refundings),  together  with
accrued  and undistributed interest thereon and undistributed cash realized from
the disposition of Bonds.
 
   
    "WHEN-ISSUED"  AND  "DELAYED  DELIVERY"  TRANSACTIONS.    The  contracts  to
purchase  Bonds delivered to  the Trustee represent an  obligation by issuers or
dealers to deliver Bonds to  the Sponsor for deposit  in the Trusts. Certain  of
the  contracts relate  to Bonds  which have not  been issued  as of  the Date of
Deposit and which are commonly referred to as "when issued" or "when, as and  if
issued"  Bonds. Although  the Sponsor  believes it  unlikely, if  such Bonds, or
replacement bonds  described below,  are not  acquired by  a Trust  or if  their
delivery  is  delayed, the  Estimated Current  Returns  and Estimated  Long Term
Returns shown  in Part  A of  this Prospectus  may be  reduced. Certain  of  the
contracts for the purchase of Bonds provide for delivery dates after the date of
settlement  for purchases made  on the Date  of Deposit. Interest  on such "when
issued" and  "delayed delivery"  Bonds  accrues to  the benefit  of  Unitholders
commencing with the first settlement date for the Units. However, in the opinion
of  counsel, Unitholders who purchase  their Units prior to  the date such Bonds
are actually delivered to the Trustee must  reduce the tax basis of their  Units
for  interest accruing on such Bonds  during the interval between their purchase
of Units and the delivery of the Bonds because such amounts constitute a  return
of  principal. As a result of such adjustment, the Estimated Current Returns set
forth in Part A of this Prospectus (which are based on the Public Offering Price
as of the business day prior to the Date of Deposit) may be slightly lower  than
that which Unitholders will receive after the first year, assuming the Portfolio
does  not change and estimated annual expense  does not vary from that set forth
under "Essential Information" in Part A of this Prospectus. Those Bonds in  each
Trust  purchased with delivery dates after  the date of settlement for purchases
made on the Date  of Deposit are  so noted in the  "Schedule of Investments"  in
Part A of this Prospectus.
    
 
    LIMITED  REPLACEMENT OF CERTAIN BONDS.   Neither the Sponsor nor the Trustee
shall be liable in any  way for any default, failure  or defect in any Bond.  In
the  event of a failure to deliver any  Bond that has been purchased for a Trust
under a contract, including those  Bonds purchased on a  when, as and if  issued
basis  ("Failed Bonds"), the Sponsor is authorized under the Indenture to direct
the Trustee to acquire  other specified Bonds ("Replacement  Bonds") to make  up
the  original corpus of the Trust within 20 days after delivery of notice of the
failed contract and the  cost to the Trust  (exclusive of accrued interest)  may
not  exceed the amount of  funds reserved for the  purchase of the Failed Bonds.
The Replacement Bonds  must satisfy  the criteria previously  described for  the
Trusts  and shall be substantially identical to the Failed Bonds they replace in
terms of (i) the exemption from  federal and state taxation; (ii) maturity  and;
(iii)  cost to the Trust. In addition,  Replacement Bonds shall not be "when, as
and if issued" Bonds. Whenever a Replacement Bond has been acquired for a Trust,
the Trustee shall, within five days after the delivery thereof, mail or  deliver
a  notice of such acquisition to all Unitholders of the Trust involved. Once the
original corpus of the Trust is acquired, the Trustee will have no power to vary
the investment of the Trust.
 
    To the extent Replacement Bonds are  not acquired, the Sponsor shall  refund
to  all Unitholders of the Trust involved  the sales charge attributable to such
Failed Bonds not replaced, and  the principal and accrued interest  attributable
to such Bonds shall be distributed not more than 30 days after the determination
of  such failure or at  such earlier time as the  Trustee in its sole discretion
deems to be in the interest of  the Unitholders. Any such accrued interest  paid
to Unitholders will be paid by the Sponsor and, accordingly, will not be treated
as  tax-exempt  income.  In the  event  Failed Bonds  in  a Trust  could  not be
replaced, the  Net Annual  Interest Income  per  Unit for  such Trust  would  be
reduced and the Estimated Current Return thereon might be lowered.
 
    SALE,  MATURITY AND REDEMPTION OF BONDS.  Certain of the Bonds may from time
to time  under certain  circumstances be  sold  or redeemed  or will  mature  in
accordance  with their terms. The proceeds from  such events will be used to pay
for  Units  redeemed   or  distributed  to   Unitholders  and  not   reinvested;
accordingly,  no assurance can be given that  a Trust will retain for any length
of time its present size and composition.
 
   
    All of the Bonds in  each Trust are subject to  being called or redeemed  in
whole  or in  part prior  to their  stated maturities  pursuant to  the optional
redemption provisions described in  the "Schedule of Investments"  in Part A  of
this  Prospectus and  in most  cases pursuant  to a  sinking fund  or special or
extraordinary redemption provisions. See the discussion of the various types  of
bond  issues,  above, for  information  on the  call  provisions of  such bonds,
particularly single family mortgage revenue bonds.
    
 
   
    The exercise of redemption or call provisions will (except to the extent the
proceeds of the called Bonds are used to pay for Unit redemptions) result in the
distribution of  principal  and may  result  in a  reduction  in the  amount  of
subsequent  interest distributions;  it may  also affect  the current  return on
Units of the Trust  involved. The exercise of  redemption or call provisions  is
more  likely  to occur  in  situations where  the  Bonds have  an  offering side
evaluation which represents a  premium over par (as  opposed to a discount  from
par).  (In  the  case  of  original issue  discount  bonds,  such  redemption is
generally to  be made  at the  issue price  plus the  amount of  original  issue
discount accreted to the date of redemption; such price is referred to herein as
"accreted  value"). Because Bonds may have been  valued at prices above or below
par value or the then current accreted  value at the time Units were  purchased,
Unitholders  may realize  gain or loss  upon the redemption  of portfolio Bonds.
(See "WHAT IS THE TAX STATUS  OF UNITHOLDERS?" and "WHEN ARE DISTRIBUTIONS  MADE
TO  UNITHOLDERS?" in Part B and the "Schedule  of Investments" in Part A of this
Prospectus.)
    
 
                                       7
<PAGE>
   
    CERTAIN TAX  MATTERS;  LITIGATION.    Certain of  the  Bonds  in  a  Trust's
portfolio  may be subject to continuing requirements regarding the actual use of
bond proceeds,  the  manner of  operation  of  the project  financed  from  bond
proceeds  or the rebate  of excess earnings  on bond proceeds,  any of which may
affect the exemption  of interest on  such Bonds from  Federal income  taxation.
Although  at the time of issuance of each  of the Bonds in each Trust an opinion
of bond counsel was rendered as to the exemption of interest on such obligations
from Federal income  taxation, and  the issuers  covenanted to  comply with  all
requirements  necessary to retain the tax-exempt  status of the Bonds, there can
be  no  assurance  that  the  respective  issuers  or  other  obligors  on  such
obligations  will fulfill  the various continuing  requirements established upon
issuance of the Bonds. A  failure to comply with  such requirements may cause  a
determination  that interest  on such obligations  is subject  to Federal income
taxation, perhaps even retroactively  from the date of  issuance of such  Bonds,
thereby   reducing  the  value  of  the  Bonds  and  subjecting  Unitholders  to
unanticipated tax liabilities.
    
 
    To the best knowledge of the Sponsor,  there is no litigation pending as  of
the  Date of Deposit in respect of  any Bonds which might reasonably be expected
to have a  material adverse effect  on any of  the Trusts. It  is possible  that
after  the Date of Deposit, litigation may be initiated with respect to Bonds in
any Trust. Any  such litigation may  affect the  validity of such  Bonds or  the
tax-exempt  nature of the interest thereon,  but while the outcome of litigation
of such nature can never be entirely predicted, the opinions of bond counsel  to
the  issuer of  each Bond  on the date  of issuance  state that  such Bonds were
validly issued and that the interest thereon is, to the extent indicated, exempt
from Federal income tax.
 
WHY AND HOW ARE THE BONDS INSURED?
 
   
Insurance guaranteeing  the  timely payment,  when  due, of  all  principal  and
interest  on the Bonds in each Insured Trust has been obtained by the Sponsor or
by the issuers or underwriters of the Bonds from the MBIA Insurance  Corporation
(the  "Insurer"). Certain of the  Bonds in an Insured Trust  may be covered by a
policy or policies of insurance obtained  by the issuers or underwriters of  the
Bonds  from  Municipal Bond  Insurance Association  (the "Association")  or Bond
Investors Guaranty Insurance Company ("BIG"). The claims-paying ability of  both
the  Insurer  and the  Association was  rated  "AAA Prime  Grade" by  Standard &
Poor's. Moody's  rates all  bond issues  insured by  either the  Insurer or  the
Association  "Aaa" and short-term loans "MIG  1." Fitch, upon request, rates all
bond issues insured by the Insurer or the Association "AAA" and short-term loans
"F-1." All such ratings designate the highest quality. The Insurer has issued  a
policy  or  policies of  insurance covering  each  of the  Bonds in  the Insured
Trusts, each policy to remain in force  until the payment in full of such  Bonds
and  whether or not  the Bonds continue to  be held by an  Insured Trust. By the
terms of each policy the Insurer  will unconditionally guarantee to the  holders
or  owners of  the Bonds the  payment, when due,  required of the  issuer of the
Bonds of an amount equal to the principal  of and interest on the Bonds as  such
payments  shall become  due but  not be paid  (except that  in the  event of any
acceleration of the  due date of  principal by reason  of mandatory or  optional
redemption,  default or otherwise, the payments  guaranteed will be made in such
amounts and  at  such times  as  would  have been  due  had there  not  been  an
acceleration).
    
 
   
    Insurance  guaranteeing the timely  payment, when due,  of all principal and
interest on certain Bonds in a Traditional  Trust may have been obtained by  the
Sponsor,  issuer or underwriter  of the particular Bonds  involved or by another
party. Such insurance, which  provides coverage substantially  the same as  that
obtained  with  respect  to  Bonds  in Insured  Trusts  as  described  above, is
effective so long as the insured Bond is outstanding and the insurer remains  in
business.  Insurance relates only  to the particular  Bond and not  to the Units
offered hereby or to their market value. Insured Bonds have received a rating of
"Aaa" by  Moody's,  "AAA"  by  Fitch  and/or  "AAA"  by  Standard  &  Poor's  in
recognition of such insurance.
    
 
   
    If  a Bond in a Traditional Trust  is insured, the "Schedule of Investments"
appearing in Part A of this Prospectus  will identify the insurer. There can  be
no  assurance  that any  insurer  listed therein  will  be able  to  satisfy its
commitments in the  event claims  are made in  the future.  However, Standard  &
Poor's,  Fitch  and/or  Moody's have  rated  the claims-paying  ability  of each
insurer "AAA," "AAA" or "Aaa," respectively.
    
 
   
    The Insurer is the principal operating subsidiary of MBIA, Inc., a New  York
Stock  Exchange listed company. MBIA, Inc. is  not obligated to pay the debts of
or claims against the Insurer. The Insurer is domiciled in the State of New York
and licensed to do business in and  subject to regulation under the laws of  all
50  states,  the District  of  Columbia, the  Commonwealth  of Puerto  Rico, the
Commonwealth of the Northern Mariana Islands,  the Virgin Islands of the  United
States  and the Territory of Guam. The Insurer has two European branches, one in
the Republic of France and the other in the Kingdom of Spain. New York has  laws
prescribing minimum capital requirements, limiting classes and concentrations of
investments  and requiring  the approval of  policy rates and  forms. State laws
also regulate the amount of both the aggregate and individual risks that may  be
insured,  the  payment  of dividends  by  the  insurer, changes  in  control and
transactions among affiliates. Additionally, the Insurer is required to maintain
contingency reserves  on its  liabilities  in certain  amounts and  for  certain
periods of time.
    
 
   
    As  of December  31, 1995  the Insurer had  admitted assets  of $3.8 billion
(audited), total liabilities of  $2.5 billion (audited),  and total capital  and
surplus  of  $1.3  billion  (audited) determined  in  accordance  with statutory
accounting  practices   prescribed   or  permitted   by   insurance   regulatory
authorities.  As of September 30, 1996, the  Insurer had admitted assets of $4.3
billion (unaudited), total  liabilities of $2.9  billion (unaudited), and  total
capital  and surplus of  $1.4 billion (unaudited)  determined in accordance with
statutory accounting practices prescribed  or permitted by insurance  regulatory
authorities.
    
 
                                       8
<PAGE>
    The  Association is comprised  of the five insurance  companies set forth in
the following table, which provides certain unaudited financial information with
respect to each of the five insurance companies comprising the Association.
 
   
                      MUNICIPAL BOND INSURANCE ASSOCIATION
      FIVE MEMBER COMPANIES ASSETS AND POLICYHOLDERS' SURPLUS (UNAUDITED)
                             AS OF MARCH 31, 1995.
                                (000'S OMITTED)
    
 
   
<TABLE>
<CAPTION>
                                                                               NEW YORK      NEW YORK       NEW YORK
                                                                              STATUTORY     STATUTORY    POLICYHOLDERS
                                                                                ASSETS     LIABILITIES      SURPLUS
                                                                             ------------  ------------  --------------
<S>                                                                          <C>           <C>           <C>
The AEtna Casualty & Surety Company........................................  $ 10,225,604  $  8,312,158  $   1,913,446
Fireman's Fund Insurance Company...........................................     7,126,217     5,116,059      2,010,158
The Travelers Indemnity Company............................................    10,461,356     8,654,130      1,807,226
CIGNA Property and Casualty Company (formerly Aetna Insurance Company).....     4,260,177     3,637,513        622,664
The Continental Insurance Company..........................................     3,060,583     2,380,723        679,860
                                                                             ------------  ------------  --------------
        Total..............................................................  $ 35,133,937  $ 28,100,583  $   7,033,354
                                                                             ------------  ------------  --------------
                                                                             ------------  ------------  --------------
</TABLE>
    
 
   
    Insurance companies  are subject  to  extensive regulation  and  supervision
where  they  do  business  by state  insurance  commissioners  who  regulate the
standards of solvency which must be maintained, the nature of and limitations on
investments, reports of financial condition, and requirements regarding reserves
for unearned premiums, losses  and other matters. A  significant portion of  the
assets  of insurance companies is required by  law to be held in reserve against
potential claims on policies and is not available to general creditors. Although
the federal  government does  not regulate  the business  of insurance,  federal
initiatives  including  pension  regulation,  controls  on  medical  care costs,
minimum standards for no-fault automobile insurance, national health  insurance,
tax  law changes affecting life insurance  companies and repeal of the antitrust
exemption for  the insurance  business can  significantly impact  the  insurance
business.
    
 
    The  above ratings are not  recommendations to buy, sell  or hold the Bonds,
and such ratings may  be subject to  revision or withdrawal at  any time by  the
rating  agencies. Any downward revision or  withdrawal of either or both ratings
may have an adverse effect on the market price of the Bonds. See the Information
Supplement--for further information concerning insurance.
 
    Because the insurance on the Bonds, if any, will be effective so long as the
Bonds are outstanding, such insurance will be taken into account in  determining
the  market value  of the  Bonds and therefore  some value  attributable to such
insurance will be included in the value of the Units of the Insured Trusts.  The
insurance  does not, however, guarantee the market  value of the Bonds or of the
Units.
 
HOW IS THE PUBLIC OFFERING PRICE DETERMINED?
 
The Public Offering Price of the Units  of each Trust is equal to the  Trustee's
determination  of the aggregate  OFFERING prices of  the Bonds deposited therein
(minus any  advancement  to the  principal  account of  the  Trust made  by  the
Trustee)  plus a sales charge set forth  in "Essential Information" in Part A of
this Prospectus, in  each case  adding to  the total  thereof cash  held by  the
Trust,  if  any,  and  dividing the  sum  so  obtained by  the  number  of Units
outstanding in the Trust. See "UNIT VALUE AND EVALUATION."
 
   
    The sales charge applicable to quantity purchases is reduced on a  graduated
scale  for sales to any purchaser  of at least $50,000 or  500 Units and will be
applied on whichever basis is more  favorable to the purchaser. For purposes  of
calculating  the applicable  sales charge,  purchasers who  have indicated their
intent to purchase a specified  amount of Units of any  Trust in the primary  or
secondary  offering period by executing and delivering a letter of intent to the
Sponsor, which letter of intent must be in a form acceptable to the Sponsor  and
shall  have a maximum duration of thirteen months, will be eligible to receive a
reduced sales charge according  to the following tables  based on the amount  of
intended  aggregate  purchases as  expressed  in the  letter  of intent.  Due to
administrative limitations and in  order to permit  adequate tracking, the  only
secondary  market  purchases that  will be  permitted to  be applied  toward the
intended specified amount and that will receive the corresponding reduced  sales
charge  are  those Units  that  are acquired  through  or from  the  Sponsor. By
establishing a letter of intent, a Unitholder agrees that the first purchase  of
Units  following the execution of  such letter of intent will  be at least 5% of
the  total  amount  of  the  intended  aggregate  purchases  expressed  in  such
Unitholder's  letter of intent. Further, through the establishment of the letter
of intent, such Unitholder agrees that Units representing 5% of the total amount
of the  intended  purchases  will be  held  in  escrow by  the  Trustee  pending
completion of these purchases. All distributions on Units held in escrow will be
credited  to  such  Unitholder's  account.  If  total  purchases  prior  to  the
expiration of the letter of intent  period equal or exceed the amount  specified
in a Unitholder's letter of intent, the Units held in escrow will be transferred
to such Unitholder's account. A Unitholder who purchases Units during the letter
of  intent period in excess  of the number of  Units specified in a Unitholder's
letter of intent, the amount of which would cause the Unitholder to be  eligible
to receive an additional sales charge reduction, will be allowed such additional
sales  charge reduction on the purchase of  Units which caused the Unitholder to
reach such  new  breakpoint level  and  on  all additional  purchases  of  Units
    
 
                                       9
<PAGE>
   
during  the letter of  intent period. If  the total purchases  are less than the
amount specified, the Unitholder involved must  pay the Sponsor an amount  equal
to  the difference between the amounts paid  for these purchases and the amounts
which would have  been paid if  the higher  sales charge had  been applied;  the
Unitholder  will, however, be entitled to any reduced sales charge qualified for
by reaching any  lower breakpoint  level. If such  Unitholder does  not pay  the
additional  amount within 20  days after written  request by the  Sponsor or the
Unitholder's securities representative, the Sponsor will instruct the Trustee to
redeem an appropriate number of the escrowed Units to meet the required payment.
By establishing  a  letter of  intent,  a Unitholder  irrevocably  appoints  the
Sponsor  as  attorney  to  give  instructions  to  redeem  any  or  all  of such
Unitholder's escrowed Units, with full power of substitution in the premises.  A
Unitholder  or his  securities representative  must notify  the Sponsor whenever
such Unitholder makes a purchase of Units  that he wishes to be counted  towards
the  intended amount.  Sales charges during  the primary offering  period are as
follows:
    
<TABLE>
<CAPTION>
                                                                                                              NATIONAL AND
                                                                                                                 STATE
                                          NATIONAL AND STATE LONG TERM                                        INTERMEDIATE
                                                     TRUSTS                   LONG INTERMEDIATE TRUSTS           TRUSTS
                                          -----------------------------     -----------------------------     ------------
<S>                                       <C>              <C>              <C>              <C>              <C>
                                            PERCENT          PERCENT          PERCENT          PERCENT          PERCENT
                                               OF             OF NET             OF             OF NET             OF
                                            OFFERING          AMOUNT          OFFERING          AMOUNT          OFFERING
            NUMBER OF UNITS*                 PRICE           INVESTED          PRICE           INVESTED          PRICE
- ----------------------------------------  ------------     ------------     ------------     ------------     ------------
Less than 500...........................         4.90 %          5.152 %           4.25 %          4.439 %           3.90%
500 but less than 1,000.................         4.75            4.987             4.15            4.330             3.70
1,000 but less than 2,500...............         4.50            4.712             3.85            4.004             3.50
2,500 but less than 5,000...............         4.25            4.439             3.60            3.734             3.25
5,000 but less than 10,000..............         3.50            3.627             3.35            3.466             3.00
10,000 but less than 25,000.............         3.00            3.093             3.00            3.093             2.75
25,000 but less than 50,000.............         2.50            2.564             2.50            2.564             2.50
50,000 or more..........................         2.00            2.041             2.00            2.041             2.00
 
<CAPTION>
 
<S>                                       <C>
                                            PERCENT
                                             OF NET
                                             AMOUNT
            NUMBER OF UNITS*                INVESTED
- ----------------------------------------  ------------
Less than 500...........................        4.058 %
500 but less than 1,000.................        3.842
1,000 but less than 2,500...............        3.627
2,500 but less than 5,000...............        3.359
5,000 but less than 10,000..............        3.093
10,000 but less than 25,000.............        2.828
25,000 but less than 50,000.............        2.564
50,000 or more..........................        2.041
</TABLE>
 
<TABLE>
<CAPTION>
                                            NATIONAL AND STATE SHORT
                                               INTERMEDIATE TRUSTS                SHORT TERM TRUSTS
                                          -----------------------------     -----------------------------
<S>                                       <C>              <C>              <C>              <C>
                                            PERCENT          PERCENT          PERCENT          PERCENT
                                               OF             OF NET             OF             OF NET
                                            OFFERING          AMOUNT          OFFERING          AMOUNT
            NUMBER OF UNITS*                 PRICE           INVESTED          PRICE           INVESTED
- ----------------------------------------  ------------     ------------     ------------     ------------
Less than 500...........................         3.00 %          3.093 %           2.50 %          2.564 %
500 but less than 1,000.................         2.80            2.881             2.30            2.354
1,000 but less than 2,500...............         2.60            2.670             2.10            2.145
2,500 but less than 5,000...............         2.35            2.407             1.85            1.885
5,000 but less than 10,000..............         2.10            2.145             1.60            1.626
10,000 but less than 25,000.............         1.85            1.885             1.35            1.368
25,000 but less than 50,000.............         1.80            1.833             1.25            1.266
50,000 or more..........................         1.50            1.523             1.15            1.163
</TABLE>
 
*Breakpoint sales charges are computed both on  a dollar basis and on the  basis
 of the number of Units purchased, using the equivalent of 500 Units to $50,000,
 2,500  Units to $250,000 etc., and will be  applied on that basis which is more
 favorable to the purchaser.
 
    For "secondary market"  sales the  Public Offering  Price per  Unit of  each
Trust is determined by adding to the Trustee's determination of the BID price of
each  Bond in the Trust  a sales charge determined  in accordance with the table
set forth below based upon the number of years remaining to the maturity of each
such Bond. See "UNIT VALUE AND EVALUATION."  The effect of this method of  sales
charge  calculation will be that different sales charge rates will be applied to
the various Bonds in a Trust portfolio based upon the maturities of such  Bonds.
As  shown, the sales charge  on Bonds in each  maturity range (and therefore the
aggregate sales charge on the purchase) is reduced with respect to purchases  of
at least $50,000 or 500 Units:
 
<TABLE>
<CAPTION>
                                                                       AMOUNT OF PURCHASE*
                              -----------------------------------------------------------------------------------------------------
<S>                           <C>          <C>          <C>          <C>          <C>          <C>          <C>          <C>
                                            $50,000      $100,000     $250,000     $500,000    $1,000,000   $2,500,000
                                UNDER          TO           TO           TO           TO           TO           TO       $5,000,000
YEARS TO MATURITY              $50,000      $99,999      $249,999     $499,999     $999,999    $2,499,999   $4,999,999    OR MORE
- ----------------------------------------   ----------   ----------   ----------   ----------   ----------   ----------   ----------
Less than 1...................         0           0            0            0            0            0            0            0
1 but less than 2.............     1.523 %     1.446 %      1.369 %      1.317 %      1.215 %      1.061 %       .900 %       .750 %
2 but less than 3.............     2.041       1.937        1.833        1.729        1.626        1.420        1.225        1.030
3 but less than 4.............     2.564       2.433        2.302        2.175        2.041        1.781        1.546        1.310
4 but less than 5.............     3.093       2.961        2.828        2.617        2.459        2.175        1.883        1.590
5 but less than 7.............     3.627       3.433        3.239        3.093        2.881        2.460        2.165        1.870
7 but less than 10............     4.167       3.951        3.734        3.520        3.239        2.828        2.489        2.150
10 but less than 13...........     4.712       4.467        4.221        4.004        3.788        3.253        2.842        2.430
13 but less than 16...........     5.263       4.988        4.712        4.439        4.167        3.627        3.169        2.710
16 or more....................     5.820       5.542        5.263        4.987        4.603        4.004        3.500        3.000
</TABLE>
 
 *Breakpoint  sales charges are computed both on a dollar basis and on the basis
  of the  number  of Units  purchased,  using the  equivalent  of 500  Units  to
  $50,000,  2,500 Units  to $250,000,  etc., and will  be applied  on that basis
  which is more favorable to the purchaser.
 
    The secondary market sales charges above  are expressed as a percent of  the
net  amount invested; expressed as  a percent of the  Public Offering Price, the
maximum sales charge on a Trust,  for instance one consisting entirely of  Bonds
with  16 years  or more to  maturity, would be  5.50% (5.820% of  the net amount
invested). The  actual secondary  market  sales charge  included in  the  Public
Offering  Price of  any particular  Trust will depend  on the  maturities of the
Bonds in the portfolio of such Trust.
 
                                       10
<PAGE>
    Pursuant to the terms of the Indenture, the Trustee may terminate a Trust if
the net asset value of such Trust, as shown by any evaluation, is less than  20%
of the original principal amount of the Trust.
 
   
    At  all  times while  Units are  being  offered for  sale, the  Sponsor will
appraise or cause to  be appraised daily  the value of  the underlying Bonds  in
each  Trust as of 4:00 p.m. eastern time, or as of any earlier closing time on a
day on  which the  New York  Stock  Exchange (the  "Exchange") is  scheduled  in
advance  to close at such earlier time and will adjust the Public Offering Price
of the Units commensurate with such  appraisal. Such Public Offering Price  will
be  effective for all orders received by a  dealer or the Sponsor at or prior to
4:00 p.m. eastern time on each such day  or as of any earlier closing time on  a
day on which the Exchange is scheduled in advance to close at such earlier time.
Orders  received after that time, or on a  day when the Exchange is closed for a
scheduled holiday  or weekend,  will be  held until  the next  determination  of
price.
    
 
   
    Accrued  interest from the preceding Record  Date to, but not including, the
settlement date of the transaction (three business days after purchase) will  be
added to the Public Offering Price to determine the purchase price of Units. See
"WHAT IS ACCRUED INTEREST?"
    
 
   
    The  graduated sales  charges set forth  above will apply  on all applicable
purchases of Nuveen  investment company securities  on any one  day by the  same
purchaser  in the amounts stated, and for  this purpose purchases of this Series
will be aggregated with concurrent purchases of any other Series or of shares of
any open-end management  investment company  of which the  Sponsor is  principal
underwriter and with respect to the purchase of which a sales charge is imposed.
Purchases  by  or for  the account  of individuals  and their  spouses, parents,
children, grandchildren, grandparents, parents-in-law, sons- and
daughters-in-law,  siblings,  a  sibling's   spouse  and  a  spouse's   siblings
("immediate  family  members") will  be aggregated  to determine  the applicable
sales charge. The graduated  sales charges are also  applicable to a trustee  or
other  fiduciary  purchasing  securities for  a  single trust  estate  or single
fiduciary account. Units may be purchased at the Public Offering Price without a
sales charge by officers or directors  and by bona fide, full-time employees  of
Nuveen,  Nuveen Advisory Corp., Nuveen Institutional Advisory Corp. and The John
Nuveen Company, including  in each  case these individuals  and their  immediate
family members (as defined above).
    
 
   
    Units  may be purchased in the primary market with sales charges of 1.70% of
the Public Offering Price for National and State Long Term Trusts, 1.35% of  the
Public Offering Price for Long Intermediate Trusts, 1.20% of the Public Offering
Price  for National and  State Intermediate Trusts, 1.0%  of the Public Offering
Price for National and  State Short Intermediate Trusts  and 1.0% of the  Public
Offering Price for Short Term Trusts by (1) investors who purchase Units through
registered  investment  advisers,  certified financial  planners  and registered
broker-dealers who  in  each case  either  charge periodic  fees  for  financial
planning,  investment  advisory or  asset management  services, or  provide such
services in connection with the establishment of an investment account for which
a comprehensive  "wrap  fee"  charge  is imposed,  (2)  bank  trust  departments
investing  funds  over which  they  exercise exclusive  discretionary investment
authority and  that  are held  in  a  fiduciary, agency,  custodial  or  similar
capacity, (3) any person who for at least 90 days, has been an officer, director
or  bona fide employee of any firm offering Units for sale to investors or their
immediate family members (as  defined above) and (4)  officers and directors  of
bank   holding  companies  that   make  Units  available   directly  or  through
subsidiaries or bank affiliates  (collectively, the "Discounted Purchases").  In
addition,  such  investors may  purchase Units  in the  secondary market  at the
Public Offering  Price for  non-breakpoint purchases  minus the  concession  the
Sponsor  typically allows to  brokers and dealers  for non-breakpoint purchases.
Notwithstanding anything  to  the contrary  in  this Prospectus,  investors  who
purchase  Units as  described in  this paragraph  will not  receive sales charge
reductions for quantity purchases.
    
 
    The initial or primary Public Offering Price  of the Units in each Trust  is
based upon a pro rata share of the OFFERING prices per Unit of the Bonds in such
Trust  plus the  applicable sales charge.  The secondary  market Public Offering
Price of each Trust is based upon a pro rata share of the BID prices per Unit of
the Bonds in such Trust plus the applicable sales charge. The OFFERING prices of
Bonds in a Trust may be expected to average between 1/2% to 2% more than the BID
prices of such  Bonds. The difference  between the bid  side evaluation and  the
offering side evaluation of the Bonds in each Trust on the business day prior to
the Date of Deposit is shown in the discussion of each Trust portfolio.
 
    Whether  or not Units are being offered for sale, the Sponsor will determine
the aggregate value of each Trust as of 4:00 p.m. eastern time: (i) on each June
30 or December 31 (or, if such date is not a business day, the last business day
prior thereto), (ii) on any day on  which a Unit is tendered for redemption  (or
the  next succeeding business day  if the date of  tender is a non-business day)
and (iii) at such other times as may be necessary. For this purpose, a "business
day" shall be any day on which  the Exchange is normally open. (See "UNIT  VALUE
AND EVALUATION.")
 
MARKET FOR UNITS
 
   
During  the  initial public  offering period,  the Sponsor  intends to  offer to
purchase Units of each  Trust at a  price equivalent to the  pro rata share  per
Unit  of the OFFERING prices of the Bonds in such Trust (plus accrued interest).
Afterward, although  it  is not  obligated  to do  so,  the Sponsor  intends  to
maintain  a secondary  market for  Units of  each Trust  at its  own expense and
continuously to offer  to purchase  Units of each  Trust at  prices, subject  to
change  at  any time,  which  are based  upon  the BID  prices  of Bonds  in the
respective portfolios of the  Trusts. UNITHOLDERS WHO WISH  TO DISPOSE OF  THEIR
UNITS SHOULD INQUIRE OF THE TRUSTEE OR THEIR BROKER AS TO THE CURRENT REDEMPTION
PRICE.  (See "HOW UNITS MAY BE REDEEMED WITHOUT CHARGE?") In connection with its
secondary marketmaking activities, the Sponsor may from time to time enter  into
secondary  market  joint  account  agreements with  other  brokers  and dealers.
Pursuant to such an agreement, the Sponsor will
    
 
                                       11
<PAGE>
purchase Units from the  broker or dealer  at the bid price  and will place  the
Units  into a joint account managed by  the Sponsor; sales from the account will
be made in accordance with the then  current prospectus and the Sponsor and  the
broker  or  dealer  will  share  profits and  losses  in  the  joint  account in
accordance with the terms of their joint account agreement.
 
   
    Certificates, if any, for Units are  delivered to the purchaser as  promptly
after the date of settlement (three business days after purchase) as the Trustee
can  complete  the mechanics  of registration,  normally  within 48  hours after
registration instructions are received. Purchasers of Units to whom Certificates
are issued will be unable  to exercise any right  of redemption until they  have
received their Certificates, properly endorsed for transfer. (See "HOW UNITS MAY
BE REDEEMED WITHOUT CHARGE?")
    
 
WHAT IS ACCRUED INTEREST?
 
Accrued  interest is the accumulation of unpaid interest on a bond from the last
day on which  interest thereon  was paid.  Interest on  Bonds in  each Trust  is
accounted  for daily on an accrual basis. For this reason, the purchase price of
Units of a Trust will  include not only the Public  Offering Price but also  the
proportionate  share  of accrued  interest to  the  date of  settlement. Accrued
interest does not  include accrual  of original  issue discount  on zero  coupon
bonds,  Stripped Obligations  or other  original issue  discount bonds. Interest
accrues to the  benefit of Unitholders  commencing with the  settlement date  of
their purchase transaction.
 
    In  an effort to reduce the amount  of accrued interest that investors would
have to pay in addition to the Public Offering Price, the Trustee has agreed  to
advance  to each Trust the amount of accrued interest due on the Bonds as of the
Date of Deposit (which has been designated  the first Record Date for all  plans
of  distribution). This  accrued interest  will be  paid to  the Sponsor  as the
holder of record of all Units on  the Date of Deposit. Consequently, the  amount
of  accrued interest  to be  added to  the Public  Offering Price  of Units will
include only accrued interest  from the Date of  Deposit to, but not  including,
the  date of  settlement of the  investor's purchase (three  business days after
purchase), less any distributions from the related Interest Account. The Trustee
will recover its  advancements (without interest  or other cost  to the  Trusts)
from interest received on the Bonds deposited in each Trust.
 
    The  Trustee has no  cash for distribution to  Unitholders until it receives
interest payments on the Bonds in  the Trusts. Since municipal bond interest  is
accrued  daily but  paid only  semi-annually, during  the initial  months of the
Trusts, the Interest  Accounts, consisting of  accrued but uncollected  interest
and  collected interest  (cash), will  be predominantly  the uncollected accrued
interest that is not available for distribution. However, due to advances by the
Trustee, the Trustee will provide a first distribution between approximately  30
and  60 days after the Date of Deposit. Assuming each Trust retains its original
size and composition  and expenses  and fees  remain the  same, annual  interest
collected  and distributed  will approximate  the estimated  Net Annual Interest
Income stated herein. However,  the amount of accrued  interest at any point  in
time  will  be greater  than  the amount  that  the Trustee  will  have actually
received and distributed to the Unitholders. Therefore, there will always remain
an item of  accrued interest  that is  included in  the Purchase  Price and  the
redemption price of the Units.
 
   
    Interest  is accounted  for daily and  a proportionate share  of accrued and
undistributed interest computed from the preceding  Record Date is added to  the
daily  valuation of each Unit of each Trust.  (See Part A of this Prospectus and
"WHEN ARE DISTRIBUTIONS MADE TO UNITHOLDERS?") As Bonds mature, or are  redeemed
or  sold,  the  accrued  interest  applicable to  such  bonds  is  collected and
subsequently distributed to Unitholders. Unitholders who sell or redeem all or a
portion of their Units will be  paid their proportionate share of the  remaining
accrued  interest to,  but not including,  the third business  day following the
date of sale or tender.
    
 
WHAT ARE ESTIMATED LONG TERM RETURN AND ESTIMATED CURRENT RETURN?
 
   
The Estimated Long Term Return for each Trust is a measure of the return to  the
investor  expected  to be  earned  over the  estimated  life of  the  Trust. The
Estimated Long Term Return represents an  average of the yields to maturity  (or
call)  of  the Bonds  in  the Trust's  portfolio  calculated in  accordance with
accepted bond practice and adjusted to reflect expenses and sales charges. Under
accepted bond practice, tax-exempt bonds are customarily offered to investors on
a "yield price" basis, which involves computation of yield to maturity or to  an
earlier  call date  (whichever produces the  lower yield), and  which takes into
account not only the interest payable on the bonds but also the amortization  or
accretion  of  any premium  over,  or discount  from,  the par  (maturity) value
inherent in the bond's purchase price. In the calculation of Estimated Long Term
Return, the average yield for a  Trust's portfolio is derived by weighting  each
Bond's yield by the market value of the Bond and by the amount of time remaining
to  the date to  which the Bond is  priced. This weighted  average yield is then
adjusted to  reflect estimated  expenses, is  compounded, and  is reduced  by  a
factor  which represents the amortization of  the sales charge over the expected
average life of  a Trust. The  Estimated Long Term  Return calculation does  not
take  into account the effect  of a first distribution which  may be less than a
regular distribution or may  be paid at  some point after 30  days (or a  second
distribution  which may be  less than a normal  distribution for Unitholders who
choose quarterly or  semi-annual plans of  distribution), and it  also does  not
take into account the difference in timing of payments to Unitholders who choose
quarterly  or semi-annual plans  of distribution, each of  which will reduce the
return.
    
 
                                       12
<PAGE>
   
    Estimated Current Return  is computed  by dividing the  Net Annual  Interest
Income per Unit by the Public Offering Price. In contrast to Estimated Long Term
Return, Estimated Current Return does not reflect the amortization of premium or
accretion  of discount, if any, on the  Bonds in a Trust's portfolio. Net Annual
Interest Income per Unit is calculated by dividing the annual interest income to
a Trust, less estimated expenses, by the number of Units outstanding.
    
 
   
    Net Annual Interest  Income per  Unit, used to  calculate Estimated  Current
Return,  will vary  with changes  in fees  and expenses  of the  Trustee and the
Evaluator and  with the  redemption,  maturity, exchange  or  sale of  Bonds.  A
Unitholder's  actual return may vary  significantly from the Estimated Long-Term
Return, based  on their  holding  period, market  interest rate  changes,  other
factors  affecting  the  prices  of  individual  bonds  in  the  portfolio,  and
differences between  the expected  remaining  life of  portfolio bonds  and  the
actual  length of time that they remain  in a Trust; such actual holding periods
may be reduced by termination of  a Trust, as described in "OTHER  INFORMATION."
Since  both  the Estimated  Current Return  and the  Estimated Long  Term Return
quoted herein are  based on  the market  value of  the underlying  Bonds on  the
business  day prior  to the  Date of  Deposit, subsequent  calculations of these
performance  measures  will  reflect  the  then  current  market  value  of  the
underlying  Bonds and may be higher or lower. The Sponsor will provide estimated
cash flow  information relating  to a  Trust without  charge to  each  potential
investor  in a Trust who  receives this prospectus and  makes an oral or written
request to the Sponsor for such information.
    
 
   
    A portion of the  monies received by  a Trust may be  treated, in the  first
year  only, as a return of principal due to the inclusion in the Trust portfolio
of "when-issued"  or  other  Bonds  having delivery  dates  after  the  date  of
settlement  for purchases  made on  the Date of  Deposit. A  consequence of this
treatment is that in the computation  of Estimated Current Return for the  first
year, such monies are excluded from Net Annual Interest Income and treated as an
adjustment  to the Public Offering Price. (See "Essential Information" appearing
in Part A  of this  Prospectus, "COMPOSITION  OF TRUSTS"  and "WHAT  IS THE  TAX
STATUS OF UNITHOLDERS?")
    
 
    A  comparison of tax-free  and equivalent taxable  estimated current returns
with the returns on  various taxable investments is  one element to consider  in
making  an  investment  decision. The  Sponsor  may  from time  to  time  in its
advertising and sales materials compare the then current estimated returns on  a
Trust  and returns  over specified periods  on other similar  Nuveen Trusts with
returns on taxable investments such as corporate or U.S. Government bonds,  bank
CD's  and  money  market accounts  or  money  market funds,  each  of  which has
investment characteristics  that  may  differ  from those  of  the  Trust.  U.S.
Government  bonds, for example, are  backed by the full  faith and credit of the
U.S. Government and bank CD's and money market accounts are insured by an agency
of the federal government. Money market accounts and money market funds  provide
stability  of principal, but pay interest at  rates that vary with the condition
of the short-term debt market. The investment characteristics of the Trusts  are
described more fully elsewhere in the Prospectus.
 
HOW WAS THE PRICE OF THE BONDS DETERMINED AT THE DATE OF DEPOSIT?
 
   
The prices at which the Bonds deposited in the Trusts would have been offered to
the  public on the business day prior to  the Date of Deposit were determined by
the Trustee on the basis  of an evaluation of such  Bonds prepared by Kenny  S&P
Evaluation  Services, a division of J. J.  Kenny Co., Inc. ("Kenny S&P"), a firm
regularly  engaged  in  the  business  of  evaluating,  quoting  or   appraising
comparable  bonds. With respect to Bonds in  Insured Trusts and insured Bonds in
Traditional Trusts, Kenny S&P evaluated the  Bonds as so insured. (See "WHY  AND
HOW ARE THE BONDS INSURED?")
    
 
    The  amount by which  the Trustee's determination of  the OFFERING PRICES of
the Bonds deposited  in the Trusts  was greater or  less than the  cost of  such
Bonds  to  the  Sponsor was  PROFIT  OR LOSS  to  the Sponsor  exclusive  of any
underwriting profit.  (See Part  A of  this Prospectus.)  The Sponsor  also  may
realize  FURTHER PROFIT OR SUSTAIN  FURTHER LOSS as a  result of fluctuations in
the Public Offering  Price of the  Units. Cash,  if any, made  available to  the
Sponsor  prior to the settlement  date for a purchase of  Units, or prior to the
acquisition of all Portfolio securities by a Trust, may be available for use  in
the Sponsor's business, and may be of benefit to the Sponsor.
 
WHAT IS THE TAX STATUS OF UNITHOLDERS?
 
   
At  the respective  times of  issuance of  the Bonds,  opinions relating  to the
validity thereof and  to the exclusion  of interest thereon  from Federal  gross
income  were rendered by bond counsel  to the respective issuing authorities. In
addition, with respect to  State Trusts, where applicable,  bond counsel to  the
issuing  authorities rendered opinions  as to the exemption  of interest on such
Bonds, when held by residents  of the state in which  the issuers of such  Bonds
are  located, from state income taxes and certain state or local intangibles and
local income taxes. For a discussion of the tax status of State Trusts, see Part
A of this Prospectus. Neither  the Sponsor nor Chapman  and Cutler has made  any
special review for the Trusts of the proceedings relating to the issuance of the
Bonds  or of the basis for the opinions rendered in connection therewith. If the
interest on a Bond should be determined to be taxable, the Bond would  generally
have  to be  sold at  a substantial  discount. In  addition, investors  could be
required to pay  income tax  on interest  received prior  to the  date of  which
interest is determined to be taxable.
    
 
    Federally  tax-exempt income, including income on  Units of the Trusts, will
be taken into consideration in computing the portion, if any, of social security
benefits received that will be included in a taxpayer's gross income subject  to
the Federal income tax.
 
                                       13
<PAGE>
   
    Gain  realized on the sale or redemption of the Bonds by the Trustee or of a
Unit by  a Unitholder  is includable  in  gross income  for Federal  income  tax
purposes,  and may be includable  in gross income for  state tax purposes. (Such
gain does not  include any  amounts received  in respect  of tax-exempt  accrued
interest  or accrued original issue discount, if any.) Sections 1288 and 1272 of
the Internal Revenue Code of 1986, as amended (the "Code") provide a complex set
of rules governing the accrual of  original issue discount. These rules  provide
that  original issue discount accrues either on the basis of a constant compound
interest rate or ratably over  the term of the Bond,  depending on the date  the
Bond  was issued. In  addition, special rules  apply if the  purchase price of a
Bond exceeds the original issue price plus the amount of original issue discount
which would have previously  accrued based upon its  issue price (its  "adjusted
issue price") to prior owners. If a Bond is acquired with accrued interest, that
portion  of the price paid for the accrued interest is added to the tax basis of
the Bond. When this accrued interest is  received, it is treated as a return  of
capital  and reduces the  tax basis of  the Bond. If  a Bond is  purchased for a
premium, the amount of the premium is added  to the tax basis of the Bond.  Bond
premium  is amortized over the remaining term of  the Bond, and the tax basis of
the Bond is reduced each tax year by the amount of the premium amortized in that
tax year. The application of these rules  will also vary depending on the  value
of  the Bond  on the  date a  Unitholder acquires  his Units  and the  price the
Unitholder pays  for  his  Units.  Unitholders should  consult  with  their  tax
advisers regarding these rules and their application.
    
 
   
    The "Revenue Reconciliation Act of 1993" (the "Tax Act") subjects tax-exempt
bonds  to the market discount  rules of the Code,  effective for bonds purchased
after April 30,  1993. In general,  market discount  is the amount  (if any)  by
which  the stated  redemption price at  maturity exceeds  an investor's purchase
price (except to  the extent that  such difference, if  any, is attributable  to
original  issue discount  not yet  accrued), subject  to a  statutory DE MINIMIS
rule. Market discount can arise based on the price the Trust pays for the  Bonds
or  the  price a  Unitholder  pays for  his  or her  Units.  Under the  Tax Act,
accretion of market discount is taxable as ordinary income; under prior law, the
accretion had been treated as capital gain. Market discount that accretes  while
the Trust holds a Bond would be recognized as ordinary income by the Unitholders
when  principal payments are  received on the  Bond, upon sale  or at redemption
(including early  redemption), or  upon the  sale or  redemption of  his or  her
Units,  unless a Unitholder elects to  include market discount in taxable income
as it accrues.  The market  discount rules  are complex  and Unitholders  should
consult their tax advisors regarding these rules and their application.
    
 
    In the opinion of Chapman and Cutler, Counsel to the Sponsor, under existing
law:
 
   
    (1) the  Trusts  are not  associations taxable  as corporations  for Federal
        income tax purposes, and interest and accrued original issue discount on
        Bonds which is excludable from gross  income under the Code will  retain
        its  status when distributed  to the Unitholders;  however such interest
        may be taken into account in  computing the alternative minimum tax,  an
        additional tax on branches of foreign corporations and the environmental
        tax  (the  "Superfund  Tax").  See "CERTAIN  TAX  MATTERS  APPLICABLE TO
        CORPORATE UNITHOLDERS", below;
    
 
   
    (2) each Unitholder of a Trust is considered  to be the owner of a pro  rata
        portion  of such Trust under Subpart E, subchapter J of Chapter 1 of the
        Code and will have a taxable event when the Trust disposes of a Bond  or
        when  the Unitholder redeems or sells Units. Unitholders must reduce the
        tax basis of their Units for their share of accrued interest received by
        the Trust, if  any, on  Bonds delivered  after the  Unitholders pay  for
        their  Units  to the  extent that  such interest  accrued on  such Bonds
        before the  date the  Trust acquired  ownership of  the Bonds  (and  the
        amount  of this reduction may exceed the amount of accrued interest paid
        to the seller) during the period from the Unitholders settlement date to
        the date  such  Bonds  are  delivered  to  the  respective  Trusts  and,
        consequently,  such Unitholders may have an  increase in taxable gain or
        reduction in capital loss  upon the disposition of  such Units. Gain  or
        loss  upon the sale or redemption of  Units is measured by comparing the
        proceeds of  such sale  or redemption  with the  adjusted basis  of  the
        Units.  If the  Trustee disposes of  Bonds (whether by  sale, payment at
        maturity, redemption or otherwise),  gain or loss  is recognized to  the
        Unitholder. The amount of any such gain or loss is measured by comparing
        the  Unitholder's  pro  rata  share  of  the  total  proceeds  from such
        disposition with  the  Unitholder's  basis for  his  or  her  fractional
        interest  in the  asset disposed  of. In  the case  of a  Unitholder who
        purchases Units, such basis (before adjustment for earned original issue
        discount  and  amortized  bond  premium,   if  any)  is  determined   by
        apportioning  the  cost of  the  Units among  each  of the  Trust assets
        ratably according to value as of the valuation date nearest the date  of
        acquisition  of the Units. The tax  basis reduction requirements of said
        Code  relating  to  amortization  of   bond  premium  may,  under   some
        circumstances,  result in the  Unitholder realizing a  taxable gain when
        his or her Units are sold or  redeemed for an amount less than or  equal
        to their original cost; and
    
 
   
    (3) any  amounts paid on defaulted Bonds  held by the Trustee under policies
        of insurance issued with respect to  such Bonds will be excludable  from
        Federal  gross income if, and to the same extent as, such interest would
        have been so excludable if  paid in the normal  course by the issuer  of
        the  defaulted  Bonds  provided  that, at  the  time  such  policies are
        purchased, the amounts paid for such policies are reasonable,  customary
        and  consistent with the  reasonable expectation that  the issuer of the
        Bonds, rather than  the insurer,  will pay  debt service  on the  Bonds.
        Paragraph  (2)  of  this  opinion is  accordingly  applicable  to policy
        proceeds representing maturing interest.
    
 
                                       14
<PAGE>
In the opinion of Carter, Ledyard & Milburn, counsel to the Trustee, and, in the
absence of a New York Trust from the Series, special counsel for the Series  for
New York tax matters, under existing law:
 
        Under  the income tax laws of the State and City of New York, each Trust
    is not an association taxable as a corporation and the income of each  Trust
    will be treated as the income of the Unitholders.
 
    For  a summary of  each opinion of  special counsel to  the respective State
Trusts for state tax matters, see Part A of this Prospectus.
 
   
    ALL STATEMENTS IN THE PROSPECTUS CONCERNING EXCLUSION FROM GROSS INCOME  FOR
FEDERAL, STATE OR OTHER TAX PURPOSES ARE THE OPINION OF COUNSEL AND ARE TO BE SO
CONSTRUED.
    
 
   
    Counsel for the Sponsor has also advised that under Section 265 of the Code,
interest  on indebtedness incurred or continued to  purchase or carry Units of a
Trust is not deductible  for Federal income tax  purposes. The Internal  Revenue
Service  has  taken the  position that  such indebtedness  need not  be directly
traceable to the purchase or carrying  of Units (however, these rules  generally
do  not apply to interest paid on indebtedness incurred to purchase or improve a
personal residence).  Also, under  Section 265  of the  Code, certain  financial
institutions that acquire Units would generally not be able to deduct any of the
interest  expense attributable to ownership of  such Units. On December 7, 1995,
the U.S. Treasury  Department released  proposed legislation  that, if  enacted,
would  generally  extend the  financial institution  rules to  all corporations,
effective for obligations  acquired after  the date  of announcement.  Investors
with questions regarding this issue should consult with their tax advisers.
    
 
   
    In  the case  of certain  of the Bonds  in the  Trust, the  opinions of bond
counsel indicate that interest on such Bonds received by a "substantial user" of
the facilities  being financed  with the  proceeds of  these Bonds,  or  persons
related thereto, for periods while such Bonds are held by such a user or related
person,  will not be excludable from  Federal gross income, although interest on
such Bonds received  by others would  be excludable from  Federal gross  income.
"Substantial  user" and  "related person"  are defined  under the  Code and U.S.
Treasury Regulations.  Any  person  who  believes  that  he  or  she  may  be  a
"substantial user" or a "related person" as so defined should contact his or her
tax adviser.
    
 
    For  purposes of computing  the alternative minimum  tax for individuals and
corporations, interest on certain specified tax-exempt private activity bonds is
included as a preference item. The Trusts do not include any such bonds.
 
   
    CERTAIN TAX  MATTERS APPLICABLE  TO CORPORATE  UNITHOLDERS. In  the case  of
certain  corporations, the alternative minimum tax  and the Superfund Tax depend
upon the corporation's alternative minimum taxable income ("AMTI"), which is the
corporation's taxable income  with certain  adjustments. One  of the  adjustment
items  used in computing AMTI and the Superfund Tax of a corporation (other than
an S corporation, Regulated Investment Company, Real Estate Investment Trust, or
REMIC) is an amount equal to 75%  of the excess of such corporation's  "adjusted
current  earnings" over an amount equal to its AMTI (before such adjustment item
and the  alternative  tax  net  operating  loss  deduction).  "Adjusted  current
earnings"  includes all tax-exempt interest, including  interest on all Bonds in
the Trust. Under current  Code provisions, the Superfund  Tax does not apply  to
tax  years beginning  on or  after January 1,  1996. However,  the Superfund Tax
could be extended  retroactively. Under  the provisions  of Section  884 of  the
Code,  a branch profits tax is levied on the "effectively connected earnings and
profits" of certain foreign corporations which include tax-exempt interest  such
as  interest on  the Bonds  in the Trust.  Unitholders should  consult their tax
advisors with respect to the particular  tax consequences to them including  the
corporate  alternative minimum tax, the Superfund Tax and the branch profits tax
imposed by Section 884 of the Code.
    
 
   
    Ownership  of  the  Units  may  result  in  collateral  federal  income  tax
consequences  to certain taxpayers,  including, without limitation, corporations
subject to either  the environmental tax  or the branch  profits tax,  financial
institutions,  certain insurance  companies, certain  S corporations, individual
recipients of Social Security or Railroad Retirement benefits and taxpayers  who
may  be deemed to have incurred (or continued) indebtedness to purchase or carry
tax-exempt obligations. Prospective investors should consult their tax  advisers
as to the applicability of any such collateral consequences.
    
 
   
    EXCEPT  AS NOTED ABOVE  AND IN PART  A OF THIS  PROSPECTUS, THE EXEMPTION OF
INTEREST ON  STATE  AND  LOCAL  OBLIGATIONS  FOR  FEDERAL  INCOME  TAX  PURPOSES
DISCUSSED  ABOVE DOES  NOT NECESSARILY RESULT  IN EXEMPTION UNDER  THE INCOME OR
OTHER TAX LAWS OF ANY  STATE OR CITY. THE LAWS  OF THE SEVERAL STATES VARY  WITH
RESPECT TO THE TAXATION OF SUCH OBLIGATIONS.
    
 
WHAT ARE NORMAL TRUST OPERATING EXPENSES?
 
No  annual advisory  fee is charged  to the  Trusts by the  Sponsor. The Sponsor
does, however, receive a fee as set  forth in "Essential Information" in Part  A
of  this  Prospectus  for regularly  evaluating  the Bonds  and  for maintaining
surveillance over the portfolio. (See "UNIT VALUE AND EVALUATION.")
 
    The Trustee receives for ordinary recurring services an annual fee for  each
plan  of distribution  for each  Trust as  set forth  in "Essential Information"
appearing in Part A of this Prospectus. Each annual fee is per $1,000  principal
amount  of the underlying  Bonds in a Trust  for that portion  of the Trust that
represents  a  particular  plan  of  distribution.  The  Trustee's  fee  may  be
periodically  adjusted in response to  fluctuations in short-term interest rates
(reflecting the  cost to  the Trustee  of advancing  funds to  a Trust  to  meet
scheduled  distributions) and  may be  further adjusted  in accordance  with the
cumulative percentage  increase  of  the United  States  Department  of  Labor's
Consumer  Price Index  entitled "All  Services Less  Rent of  Shelter" since the
establishment of the Trusts.  The Trustee has  the use of  funds, if any,  being
held in the Interest and
 
                                       15
<PAGE>
   
Principal  Accounts of each Trust for  future distributions, payment of expenses
and  redemptions.  These  Accounts  are  non-interest  bearing  to  Unitholders.
Pursuant  to normal  banking procedures,  the Trustee  benefits from  the use of
funds held therein. Part of the  Trustee's compensation for its services to  the
Trusts is expected to result from such use of these funds.
    
 
    Premiums  for the policies  of insurance obtained  by the Sponsor  or by the
Bond issuers with respect to the Bonds in the Insured Trusts and with respect to
insured Bonds in Traditional Trusts have been paid in full prior to the  deposit
of the Bonds in the Trusts, and the value of such insurance has been included in
the evaluation of the Bonds in each Trust and accordingly in the Public Offering
Price  of Units of each Trust. There  are no annual continuing premiums for such
insurance.
 
   
    All or  a portion  of  the expenses  incurred  in establishing  the  Trusts,
including costs of preparing the registration statement, the trust indenture and
other  closing  documents, registering  Units with  the Securities  and Exchange
Commission and states, the  initial audit of each  Trust portfolio, the  initial
evaluation,  legal fees, the  initial fees and  expenses of the  Trustee and any
other non-material  out-of-pocket  expenses, will  be  paid by  the  Trusts  and
amortized over the first five years of such Trusts. The following are additional
expenses of the Trusts and, when paid by or are owed to the Trustee, are secured
by  a lien  on the  assets of  the Trust  or Trusts  to which  such expenses are
allocable: (1) the expenses and costs of any action undertaken by the Trustee to
protect the Trusts  and the  rights and interests  of the  Unitholders; (2)  all
taxes  and other governmental charges  upon the Bonds or  any part of the Trusts
(no such taxes or charges are being levied  or made or, to the knowledge of  the
Sponsor,  contemplated); (3) amounts payable to the Trustee as fees for ordinary
recurring  services  and  for  extraordinary  non-recurring  services   rendered
pursuant to the Indenture, all disbursements and expenses including counsel fees
(including  fees  of bond  counsel which  the Trustee  may retain)  sustained or
incurred by  the  Trustee  in  connection  therewith;  and  (4)  any  losses  or
liabilities  accruing to  the Trustee without  negligence, bad  faith or willful
misconduct on its part. The Trustee is  empowered to sell Bonds in order to  pay
these  amounts if funds  are not otherwise available  in the applicable Interest
and Principal Accounts.
    
 
    The Indenture requires each Trust  to be audited on  an annual basis at  the
expense  of the Trust by independent public accountants selected by the Sponsor.
The Trustee  shall not  be  required, however,  to cause  such  an audit  to  be
performed  if its cost to a Trust shall exceed $.05 per Unit on an annual basis.
Unitholders of a  Trust covered by  an audit may  obtain a copy  of the  audited
financial statements upon request.
 
WHEN ARE DISTRIBUTIONS MADE TO UNITHOLDERS?
 
Interest received by the Trustee on the Bonds in each Trust, including that part
of  the proceeds of  any disposition of Bonds  which represents accrued interest
and including  any insurance  proceeds representing  interest due  on  defaulted
Bonds,  shall be credited to the "Interest  Account" of such Trust and all other
moneys received by the Trustee shall  be credited to the "Principal Account"  of
such Trust.
 
    The  pro rata share of  cash in the Principal Account  in each Trust will be
computed as of each semi-annual Record Date and distributions to the Unitholders
as of such Record Date will be made on or shortly after the fifteenth day of the
month. Proceeds received from the disposition, including sale, call or maturity,
of any of the Bonds and all amounts  paid with respect to zero coupon bonds  and
Stripped  Obligations will be held  in the Principal Account  and either used to
pay for Units  redeemed or distributed  on the Distribution  Date following  the
next semi-annual Record Date. The Trustee is not required to make a distribution
from  the  Principal  Account  of  any Trust  unless  the  amount  available for
distribution in such account equals at least ten cents per Unit.
 
    The pro rata share of the Interest Account in each Trust will be computed by
the Trustee each month as of each Record Date and distributions will be made  on
or  shortly after the fifteenth day of the month to Unitholders of such Trust as
of the Record Date who are entitled to distributions at that time under the plan
of distribution chosen. Persons who purchase  Units between a Record Date and  a
Distribution Date will receive their first distribution on the Distribution Date
following the next Record Date under the applicable plan of distribution.
 
    Purchasers  of  Units  who desire  to  receive interest  distributions  on a
monthly or quarterly basis may elect to do so at the time of purchase during the
initial public offering  period. Those indicating  no choice will  be deemed  to
have  chosen the  semi-annual distribution  plan. All  Unitholders, however, who
purchase Units during the  initial public offering period  and who hold them  of
record on the first Record Date will receive the first distribution of interest.
Thereafter, Record Dates for monthly distributions will be the first day of each
month;  Record  Dates  for quarterly  distributions  will  be the  first  day of
February,  May,  August   and  November;  and   Record  Dates  for   semi-annual
distributions  will be  the first day  of May and  November. See Part  A of this
Prospectus for details of distributions per Unit of each Trust under the various
plans based upon estimated  Net Annual Interest Income  at the Date of  Deposit.
The  amount of  the regular distributions  will generally change  when Bonds are
redeemed, mature or are sold or when fees and expenses increase or decrease. For
the purpose of minimizing  fluctuations in the  distributions from the  Interest
Account  of a Trust, the Trustee is authorized to advance such amounts as may be
necessary to provide for interest distributions of approximately equal  amounts.
The  Trustee shall be  reimbursed, without interest, for  any such advances from
funds in  the Interest  Account of  such  Trust. The  Trustee's fee  takes  into
account  the costs  attributable to  the outlay of  capital needed  to make such
advances.
 
    The plan of  distribution selected  by a  Unitholder will  remain in  effect
until  changed.  Unitholders  purchasing  Units  in  the  secondary  market will
initially receive distributions  in accordance  with the election  of the  prior
owner. Unitholders
 
                                       16
<PAGE>
desiring  to change their  plan of distribution  may do so  by sending a written
notice requesting the change, together with any Certificate(s), to the  Trustee.
The notice and any Certificate(s) must be received by the Trustee not later than
the  semi-annual Record Date to be  effective as of the semi-annual distribution
following the subsequent semi-annual Record  Date. Unitholders are requested  to
make  any  such changes  within 45  days  prior to  the applicable  Record Date.
Certificates should only be sent by registered or certified mail to minimize the
possibility of  their being  lost or  stolen. (See  "OWNERSHIP AND  TRANSFER  OF
UNITS.")
 
   
    As  of the first day of each month the Trustee will deduct from the Interest
Account of a Trust or, to the extent funds are not sufficient therein, from  the
Principal  Account of a  Trust, amounts needed  for payment of  expenses of such
Trust. The Trustee also may withdraw from said accounts such amount, if any,  as
it  deems necessary to establish a  reserve for any governmental charges payable
out of such  Trust. Amounts so  withdrawn shall not  be considered a  part of  a
Trust's  assets until such time  as the Trustee shall return  all or any part of
such amounts to the appropriate account. In addition, the Trustee shall withdraw
from the Interest Account and the Principal  Account of a Trust such amounts  as
may  be necessary to  cover redemptions of  Units of such  Trust by the Trustee.
Funds which are available for  future distributions, redemptions and payment  of
expenses  are held in accounts which are non-interest bearing to Unitholders and
are available for use by the Trustee pursuant to normal banking procedures.
    
 
ACCUMULATION PLAN
 
   
The Sponsor is also the principal  underwriter of several open-end mutual  funds
(the  "Accumulation Funds") into which Unitholders  may choose to reinvest Trust
distributions. Unitholders  may elect  to  reinvest principal  distributions  or
interest  and principal  distributions automatically, without  any sales charge.
Each Accumulation  Fund  has  investment  objectives  which  differ  in  certain
respects  from those of the Trusts and  may invest in securities which would not
be eligible  for  deposit in  the  Trusts. Further  information  concerning  the
Accumulation  Plan  and  a  list  of Accumulation  Funds  is  set  forth  in the
Information Supplement of this Prospectus,  which may be obtained by  contacting
the Trustee at the phone number listed on the back cover of this Prospectus.
    
 
Participants  may at any time, by so  notifying the Trustee in writing, elect to
change  the  Accumulation  Fund  into   which  their  distributions  are   being
reinvested,  to change from principal only  reinvestment to reinvestment of both
principal and interest or vice versa, or to terminate their participation in the
Accumulation Plan altogether and receive future distributions on their Units  in
cash.  There will be no  charge or other penalty for  such change of election or
termination. The character of Trust  distributions for income tax purposes  will
remain unchanged even if they are reinvested in an Accumulation Fund.
 
HOW DETAILED ARE REPORTS TO UNITHOLDERS?
 
   
The  Trustee  shall  furnish Unitholders  of  a  Trust in  connection  with each
distribution, a statement of the amount of  interest, if any, and the amount  of
other  receipts (received  since the preceding  distribution) being distributed,
expressed in each case  as a dollar  amount representing the  pro rata share  of
each Unit of a Trust outstanding and a year to date summary of all distributions
paid  on said Units.  Within a reasonable period  of time after  the end of each
calendar year, the Trustee shall furnish to each person, who at any time  during
the  calendar year  was a  registered Unitholder  of a  Trust, a  statement with
respect to  such  Trust  (i)  as to  the  Interest  Account:  interest  received
(including  amounts  representing  interest  received  upon  any  disposition of
Bonds), and, except  for any  State Trust, the  percentage of  such interest  by
states  in which the issuers  of the Bonds are  located, deductions for fees and
expenses of such Trust, redemption of Units and the balance remaining after such
distributions and deductions,  expressed in  each case  both as  a total  dollar
amount  and as  a dollar  amount representing  the pro  rata share  of each Unit
outstanding on the  last business  day of  such calendar  year; (ii)  as to  the
Principal  Account: the dates of  disposition of any Bonds  and the net proceeds
received therefrom (excluding  any portion representing  accrued interest),  the
amount  paid for purchase of Replacement  Bonds, the amount paid upon redemption
of Units, deductions for  payment of applicable taxes  and fees and expenses  of
the  Trustee, and the balance remaining  after such distributions and deductions
expressed both as a total dollar amount and as a dollar amount representing  the
pro  rata  share of  each  Unit outstanding  on the  last  business day  of such
calendar year;  (iii)  a  list  of  the Bonds  held  and  the  number  of  Units
outstanding  on the last business day of such calendar year; (iv) the Unit Value
based upon the last computation thereof made during such calendar year; and  (v)
amounts actually distributed during such calendar year from the Interest Account
and  from  the Principal  Account, separately  stated,  expressed both  as total
dollar amounts and  as dollar amounts  representing the pro  rata share of  each
Unit  outstanding. Each annual  statement will reflect  pertinent information in
respect of  all  plans of  distribution  so  that Unitholders  may  be  informed
regarding the results of other plans of distribution.
    
 
UNIT VALUE AND EVALUATION
 
   
The  value of each  Trust is determined by  the Sponsor on the  basis of (1) the
cash on hand in the Trust or moneys  in the process of being collected, (2)  the
value  of the Bonds in  the Trust based on  the BID prices of  the Bonds and (3)
interest  accrued  thereon   not  subject  to   collection,  LESS  (1)   amounts
representing  taxes or governmental charges payable out of the Trust and (2) the
accrued expenses of the Trust. The result of such computation is divided by  the
number  of Units of such  Trust outstanding as of  the date thereof to determine
the per Unit value ("Unit Value") of  such Trust. The Sponsor may determine  the
value  of the Bonds in each Trust (1) on  the basis of current BID prices of the
Bonds obtained from dealers or brokers who customarily deal in bonds  comparable
to  those held by a  Trust, (2) if bid  prices are not available  for any of the
Bonds, on the basis of bid prices for comparable bonds, (3) by causing the value
of the Bonds to be determined by others
    
 
                                       17
<PAGE>
engaged in the practice of evaluating, quoting or appraising comparable bonds or
(4) by any combination of  the above. Although the Unit  Value of each Trust  is
based on the BID prices of the Bonds, the Units are sold initially to the public
at the Public Offering Price based on the OFFERING prices of the Bonds.
 
    Because  the insurance obtained  by the Sponsor  or by the  issuers of Bonds
with respect to  the Bonds in  the Insured  Trusts and with  respect to  insured
Bonds  in Traditional Trusts is effective so long as such Bonds are outstanding,
such insurance will be  taken into account in  determining the bid and  offering
prices  of such  Bonds and therefore  some value attributable  to such insurance
will be included in the value of Units of Trusts that include such Bonds.
 
HOW UNITS OF THE TRUSTS ARE DISTRIBUTED TO THE PUBLIC
 
   
Nuveen, in addition to being the Sponsor, is the sole Underwriter of the  Units.
It  is  the  intention  of  the  Sponsor  to  qualify  Units  of  National, Long
Intermediate, Intermediate, Short  Intermediate and Short  Term Trusts for  sale
under  the  laws of  substantially all  of the  states of  the United  States of
America, and Units  of State Trusts  only in the  state for which  the Trust  is
named and selected other states.
    
 
    Promptly following the deposit of Bonds in exchange for Units of the Trusts,
it  is the practice of the Sponsor to place all of the Units as collateral for a
letter or letters of credit from one or more commercial banks under an agreement
to release such Units from time to  time as needed for distribution. Under  such
an  arrangement  the Sponsor  pays  such banks  compensation  based on  the then
current interest  rate. This  is  a normal  warehousing arrangement  during  the
period  of  distribution of  the Units  to public  investors. To  facilitate the
handling of  transactions,  sales of  Units  shall be  limited  to  transactions
involving a minimum of either $5,000 or 50 Units, whichever is less. The Sponsor
reserves the right to reject, in whole or in part, any order for the purchase of
Units.
 
    The  Sponsor plans to allow a discount  to brokers and dealers in connection
with  the  primary  distribution   of  Units  and   also  in  secondary   market
transactions. The primary market discounts are as follows:
 
<TABLE>
<CAPTION>
                                                         DISCOUNT PER UNIT
                                --------------------------------------------------------------------
<S>                             <C>         <C>            <C>            <C>            <C>
                                 NATIONAL    LONG INTER-                  SHORT INTER-
                                AND STATE      MEDIATE     INTERMEDIATE      MEDIATE     SHORT TERM
NUMBER OF UNITS*                  TRUSTS       TRUSTS         TRUSTS         TRUSTS        TRUSTS
- ------------------------------  ----------  -------------  -------------  -------------  -----------
Less than 500.................    $3.20         $2.90          $2.70          $2.00         $1.50
500 but less than 1,000.......     3.20         2.90           2.70           2.00          1.50
1,000 but less than 2,500.....     3.20         2.70           2.50           1.80          1.30
2,500 but less than 5,000.....     3.20         2.45           2.25           1.55          1.05
5,000 but less than 10,000....     2.50         2.45           2.25           1.55          1.05
10,000 but less than 25,000...     2.00         2.00           2.00           1.30           .80
25,000 but less than 50,000...     1.75         1.75           1.75           1.30           .60
50,000 or more................     1.75         1.50           1.50           1.00           .60
</TABLE>
 
*Breakpoint  sales charges and related dealer concessions are computed both on a
 dollar basis and  on the  basis of  the number  of Units  purchased, using  the
 equivalent  of 500 Units to  $50,000, 2,500 Units to  $250,000 etc. and will be
 applied on that basis which is more favorable to the purchaser.
 
    The Sponsor currently intends  to maintain a secondary  market for Units  of
each  Trust. See  "MARKET FOR  UNITS." The  amount of  the dealer  concession on
secondary market purchases of Trust Units  through the Sponsor will be  computed
based  upon the value of  the Bonds in the  Trust portfolio, including the sales
charge computed as described in "HOW IS THE PUBLIC OFFERING PRICE  DETERMINED?",
and  adjusted to reflect the  cash position of the  Trust principal account, and
will vary with the size of the purchase as shown in the following table:
 
<TABLE>
<CAPTION>
                                                               AMOUNT OF PURCHASE*
                            -----------------------------------------------------------------------------------------
<S>                         <C>        <C>        <C>        <C>        <C>        <C>         <C>         <C>
                                        $50,000   $100,000   $250,000   $500,000   $1,000,000  $2,500,000
                              UNDER       TO         TO         TO         TO          TO          TO      $5,000,000
YEARS TO MATURITY            $50,000    $99,999   $249,999   $499,999   $999,999   $2,499,999  $4,999,999   OR MORE
- --------------------------  ---------  ---------  ---------  ---------  ---------  ----------  ----------  ----------
Less than 1...............      0          0          0          0          0          0           0           0
1 but less than 2.........    1.00%      .90%       .85%       .80%       .70%        .55%       .467%       .389%
2 but less than 3.........    1.30%      1.20%      1.10%      1.00%      .90%        .73%       .634%       .538%
3 but less than 4.........    1.60%      1.45%      1.35%      1.25%      1.10%       .90%       .781%       .662%
4 but less than 5.........    2.00%      1.85%      1.75%      1.55%      1.40%      1.25%       1.082%      .914%
5 but less than 7.........    2.30%      2.15%      1.95%      1.80%      1.65%      1.50%       1.320%      1.140%
7 but less than 10........    2.60%      2.45%      2.25%      2.10%      1.95%      1.70%       1.496%      1.292%
10 but less than 13.......    3.00%      2.80%      2.60%      2.45%      2.30%      2.00%       1.747%      1.494%
13 but less than 16.......    3.25%      3.15%      3.00%      2.75%      2.50%      2.15%       1.878%      1.606%
16 or more................    3.50%      3.50%      3.40%      3.35%      3.00%      2.50%       2.185%      1.873%
</TABLE>
 
 *Breakpoint sales charges and related dealer concessions are computed both on a
  dollar basis and  on the basis  of the  number of Units  purchased, using  the
  equivalent of 500 Units to $50,000, 2,500 Units to $250,000, etc., and will be
  applied on that basis which is more favorable to the purchaser.
 
    The  Sponsor reserves the  right to change  the foregoing dealer concessions
from time to time.
 
   
    At the  discretion of  the Sponsor,  volume incentives  can be  earned as  a
marketing  allowance by  dealer firms who  reach cumulative firm  sales or sales
arrangement levels of a specified number of Units of an individual Trust  during
the primary
    
 
                                       18
<PAGE>
   
offering  period  as set  forth  in the  table below.  For  firms that  meet the
necessary volume level for a Trust, volume incentives may be given on all trades
involving that Trust originated from or by that firm during the primary offering
period.
    
 
   
Primary Market Volume Incentives
    
 
   
<TABLE>
<CAPTION>
                                   PER TRUST SALES LEVEL
AVERAGE MATURITY                     DURING THE PRIMARY      VOLUME INCENTIVE
OF TRUST                              OFFERING PERIOD            PER UNIT
- -------------------------------  --------------------------  -----------------
<S>                              <C>                         <C>
Less than 6 years                      At least 5,000 Units      $    0.05
6 but less than 15 years               At least 2,500 Units      $    0.10
15 years or more                       At least 2,500 Units      $    0.20
</TABLE>
    
 
   
    In addition, a volume  incentive of $2.50  per $1,000 of  Units sold can  be
earned by dealer firms as a marketing allowance for secondary market sales of at
least $1 million of Nuveen Unit Trust units per calendar quarter.
    
 
   
    Only sales through the Sponsor qualify for volume incentives and for meeting
minimum  requirements. The  Sponsor reserves the  right to modify  or change the
volume incentive schedule  at any time  and make the  determination as to  which
firms qualify for the marketing allowance and the amount paid.
    
 
   
    Registered  investment advisers, certified financial planners and registered
broker-dealers who  in  each case  either  charge periodic  fees  for  financial
planning,  investment  advisory or  asset management  services, or  provide such
services in connection with the establishment of an investment account for which
a comprehensive  "wrap  fee"  charge  is imposed,  and  bank  trust  departments
investing  funds  over which  they  exercise exclusive  discretionary investment
authority and  that  are held  in  a  fiduciary, agency,  custodial  or  similar
capacity,  are not entitled to receive any  dealer concession for any sales made
to investors which  qualified as  "Discounted Purchases" during  the primary  or
secondary market. (See "HOW IS THE PUBLIC OFFERING PRICE DETERMINED?")
    
 
    Certain  commercial banks are making Units  of the Trusts available to their
customers on  an agency  basis. A  portion of  the sales  charge paid  by  these
customers  is retained by or  remitted to the banks in  the amounts shown in the
above table.  The Glass-Steagall  Act prohibits  banks from  underwriting  Trust
Units;  the Act  does, however, permit  certain agency  transactions and banking
regulators have not indicated that these particular agency transactions are  not
permitted  under the Act. In Texas and  in certain other states, any bank making
Units available must be registered as a broker-dealer under state law.
 
OWNERSHIP AND TRANSFER OF UNITS
 
The ownership of  Units is  evidenced by book  entry positions  recorded on  the
books  and records of the Trustee  unless the Unitholder expressly requests that
the purchased Units be evidenced in Certificate form. The Trustee is  authorized
to treat as the owner of Units that person who at the time is registered as such
on  the books of the Trustee. Any  Unitholder who holds a Certificate may change
to book entry ownership by submitting to the Trustee the Certificate along  with
a written request that the Units represented by such Certificate be held in book
entry form. Likewise, a Unitholder who holds Units in book entry form may obtain
a  Certificate for such  Units by written  request to the  Trustee. Units may be
held in denominations of one Unit or any multiple or fraction thereof. Fractions
of Units are computed to three  decimal places. Any Certificates issued will  be
numbered  serially for identification, and are  issued in fully registered form,
transferable only  on the  books of  the Trustee.  Book entry  Unitholders  will
receive a Book Entry Position Confirmation reflecting their ownership.
 
    For  Trusts allowing optional plans  of distribution, Certificates for Units
will bear  an  appropriate notation  on  their  face indicating  which  plan  of
distribution has been selected. When a change is made, the existing Certificates
must  be surrendered to the  Trustee and new Certificates  issued to reflect the
currently effective  plan of  distribution. There  will be  no charge  for  this
service.  Holders of book entry  Units can change their  plan of distribution by
making a written  request to  the Trustee,  which will  issue a  new Book  Entry
Position Confirmation to reflect such change.
 
    Units  are transferable by making  a written request to  the Trustee and, in
the case of Units  evidenced by Certificate(s),  by presenting and  surrendering
such  Certificate(s) to the Trustee, at its  address listed on the back cover of
this Part B  of the Prospectus,  properly endorsed or  accompanied by a  written
instrument  or  instruments  of  transfer.  The  Certificate(s)  should  be sent
registered or  certified  mail  for  the  protection  of  the  Unitholder.  Each
Unitholder  must sign such written request,  and such Certificate(s) or transfer
instrument, exactly as his  name appears on (a)  the face of the  Certificate(s)
representing  the  Units  to be  transferred,  or  (b) the  Book  Entry Position
Confirmation(s) relating to the Units to be transferred. Such signature(s)  must
be guaranteed by a guarantor acceptable to the Trustee. In certain instances the
Trustee  may require  additional documents  such as,  but not  limited to, trust
instruments, certificates of death, appointments as executor or administrator or
certificates of corporate authority. Mutilated Certificates must be  surrendered
to  the Trustee in order for a replacement Certificate to be issued. Although at
the date hereof no charge is made and none is contemplated, a Unitholder may  be
required  to pay $2.00 to the Trustee  for each Certificate reissued or transfer
of Units requested and to  pay any governmental charge  which may be imposed  in
connection therewith.
 
REPLACEMENT OF LOST, STOLEN OR DESTROYED CERTIFICATES.
 
    To  obtain a new  Certificate replacing one  that has been  lost, stolen, or
destroyed,  the   Unitholder   must   furnish  the   Trustee   with   sufficient
indemnification   and  pay  such  expenses  as   the  Trustee  may  incur.  This
indemnification must be in the
 
                                       19
<PAGE>
form of  an  Open Penalty  Bond  of Indemnification.  The  premium for  such  an
indemnity  bond may vary, but currently amounts to 1% of the market value of the
Units represented by  the Certificate. In  the case  however, of a  Trust as  to
which  notice of  termination has been  given, the premium  currently amounts to
0.5% of the market value of the Units represented by such Certificate.
 
HOW UNITS MAY BE REDEEMED WITHOUT CHARGE
 
   
Unitholders may redeem all or a portion  of their Units by (1) making a  written
request  for such redemption (book entry Unitholders may use the redemption form
on the reverse side of their Book Entry Position Confirmation) to the Trustee at
its address  listed  on  the  back  cover of  this  Part  B  of  the  Prospectus
(redemptions  of 1,000 Units or more will require a signature guarantee), (2) in
the case of Units evidenced by a Certificate, by also tendering such Certificate
to the Trustee, duly endorsed or  accompanied by proper instruments of  transfer
with signatures guaranteed as explained above, or provide satisfactory indemnity
required  in  connection with  lost, stolen  or  destroyed Certificates  and (3)
payment of applicable governmental charges, if any. Certificates should be  sent
only  by registered or certified mail to minimize the possibility of their being
lost or stolen. (See "OWNERSHIP AND TRANSFER OF UNITS.") No redemption fee  will
be   charged.  A  Unitholder  may  authorize  the  Trustee  to  honor  telephone
instructions for  the  redemption  of  Units held  in  book  entry  form.  Units
represented  by Certificates may  not be redeemed by  telephone. The proceeds of
Units redeemed by telephone will  be sent by check  either to the Unitholder  at
the  address specified on his account or to a financial institution specified by
the Unitholder for credit to the account of the Unitholder. A Unitholder wishing
to  use  this  method  of  redemption  must  complete  a  Telephone   Redemption
Authorization  Form and  furnish the Form  to the  Trustee. Telephone Redemption
Authorization  Forms   can   be   obtained  from   a   Unitholder's   registered
representative  or by calling the  Trustee. Once the completed  Form is on file,
the Trustee will honor telephone  redemption requests by any authorized  person.
The  time a  telephone redemption  request is  received determines  the "date of
tender" as discussed below. The redemption proceeds will be mailed within  three
business days following the telephone redemption request. Only Units held in the
name  of individuals may be redeemed by telephone; accounts registered in broker
name, or  accounts  of  corporations or  fiduciaries  (including  among  others,
trustees,  guardians, executors  and administrators)  may not  use the telephone
redemption privilege.
    
 
   
    On the third business day following the date of tender, the Unitholder  will
be  entitled to receive  in cash for each  Unit tendered an  amount equal to the
Unit Value of  such Trust determined  by the  Trustee, as of  4:00 p.m.  eastern
time,  or as  of any  earlier closing  time on  a day  on which  the Exchange is
scheduled in advance to  close at such  earlier time, on the  date of tender  as
defined  hereafter,  plus  accrued interest  to,  but not  including,  the third
business day after the date of  tender ("Redemption Price"). The price  received
upon  redemption may  be more  or less  than the  amount paid  by the Unitholder
depending on the value of  the Bonds on the  date of tender. Unitholders  should
check  with the Trustee or their broker to determine the Redemption Price before
tendering Units.
    
 
   
    The "date of  tender" is  deemed to  be the date  on which  the request  for
redemption  of Units is received  in proper form by  the Trustee, except that as
regards a redemption request received after 4:00 p.m. eastern time, or as of any
earlier closing time on a day on  which the Exchange is scheduled in advance  to
close  at such  earlier time, or  on any day  on which the  Exchange is normally
closed, the date of tender  is the next day on  which such Exchange is  normally
open  for trading and such request will be  deemed to have been made on such day
and the redemption  will be effected  at the Redemption  Price computed on  that
day.
    
 
    Accrued  interest paid  on redemption shall  be withdrawn  from the Interest
Account of the  appropriate Trust or,  if the balance  therein is  insufficient,
from  the Principal Account of such Trust.  All other amounts paid on redemption
shall be withdrawn from the Principal Account. The Trustee is empowered to  sell
underlying  Bonds of a  Trust in order  to make funds  available for redemption.
(See "HOW BONDS MAY  BE REMOVED FROM  THE TRUSTS.") Units  so redeemed shall  be
cancelled.  To  the  extent that  Bonds  are sold  from  a Trust,  the  size and
diversity of such Trust will  be reduced. Such sales may  be required at a  time
when  Bonds would not  otherwise be sold  and might result  in lower prices than
might otherwise be realized.
 
   
    The Redemption Price is  determined on the  basis of the  BID prices of  the
Bonds  in each Trust, while  the initial Public Offering  Price of Units will be
determined on the  basis of the  OFFERING prices of  the Bonds as  of 4:00  p.m.
eastern  time on any day on which the  Exchange is normally open for trading, or
as of any earlier closing  time on a day on  which the Exchange is scheduled  in
advance to close at such earlier time, and such determination is made. As of any
given time, the difference between the bid and offering prices of such Bonds may
be  expected to average 1/2% to 2% of  principal amount. In the case of actively
traded Bonds, the difference may be  as little as 1/4 to  1/2 of 1%, and in  the
case of inactively traded Bonds such difference usually will not exceed 3%.
    
 
    The  right  of redemption  may be  suspended and  payment postponed  for any
period during  which  the Securities  and  Exchange Commission  determines  that
trading  in the municipal bond market is restricted or an emergency exists, as a
result  of  which  disposal  or  evaluation  of  the  Bonds  is  not  reasonably
practicable, or for such other periods as the Securities and Exchange Commission
may by order permit.
 
    Under  regulations issued by the Internal  Revenue Service, the Trustee will
be required to withhold a specified percentage of the principal amount of a Unit
redemption if the Trustee has not been furnished the redeeming Unitholder's  tax
identification  number in the manner required by such regulations. Any amount so
withheld is transmitted to the Internal
 
                                       20
<PAGE>
Revenue Service and may be recovered by  the Unitholder only when filing his  or
her  tax return. Under normal circumstances the Trustee obtains the Unitholder's
tax identification number from the selling broker at the time the Certificate or
Book Entry Return  Confirmation is  issued, and this  number is  printed on  the
Certificate or Book Entry Return Confirmation and on distribution statements. If
a  Unitholder's tax identification number does not appear as described above, or
if it is incorrect, the Unitholder  should contact the Trustee before  redeeming
Units  to determine  what action,  if any,  is required  to avoid  this "back-up
withholding."
 
HOW UNITS MAY BE PURCHASED BY THE SPONSOR
 
The Trustee will notify the  Sponsor of any tender  of Units for redemption.  If
the  Sponsor's bid in  the secondary market  at that time  equals or exceeds the
Redemption Price it may purchase such Units by notifying the Trustee before  the
close  of business on the  second succeeding business day  and by making payment
therefor to  the  Unitholder not  later  than the  day  on which  payment  would
otherwise have been made by the Trustee. (See "HOW UNITS MAY BE REDEEMED WITHOUT
CHARGE.")  The Sponsor's current practice  is to bid at  the Redemption Price in
the secondary market. Units held by the  Sponsor may be tendered to the  Trustee
for redemption as any other Units.
 
HOW BONDS MAY BE REMOVED FROM THE TRUSTS
 
Bonds will be removed from a Trust as they mature or are redeemed by the issuers
thereof.  See Part A of  this Prospectus and "RISK  FACTORS" for a discussion of
call provisions of portfolio Bonds.
 
   
    The Indenture also  empowers the Trustee  to sell Bonds  for the purpose  of
redeeming  Units tendered by any Unitholder, and for the payment of expenses for
which income may not be available. Under the Indenture, the Sponsor is obligated
to provide the Trustee with a current list of Bonds in each Trust to be sold  in
such  circumstances. In deciding which Bonds  should be sold the Sponsor intends
to consider, among  other things, such  factors as: (1)  market conditions;  (2)
market  prices  of  the  Bonds;  (3)  the  effect  on  income  distributions  to
Unitholders of the sale of various Bonds; (4) the effect on principal amount  of
underlying  Bonds  per Unit  of the  sale  of various  Bonds; (5)  the financial
condition of the issuers; and (6) the effect of the sale of various Bonds on the
investment character of the Trust. Such sales, if required, could result in  the
sale  of Bonds by the Trustee at prices less than original cost to the Trust. To
the extent Bonds are sold, the size and diversity of such Trust will be reduced.
    
 
    In addition, the  Sponsor is empowered  to direct the  Trustee to  liquidate
Bonds upon the happening of certain other events, such as default in the payment
of principal and/or interest, an action of the issuer that will adversely affect
its  ability to continue payment of the  principal of and interest on its Bonds,
or an  adverse  change  in  market, revenue  or  credit  factors  affecting  the
investment  character of the Bonds. If a default in the payment of the principal
of and/or interest  on any  of the  Bonds occurs, and  if the  Sponsor fails  to
instruct  the Trustee whether to  sell or continue to  hold such Bonds within 30
days after  notification by  the Trustee  to the  Sponsor of  such default,  the
Indenture  provides that  the Trustee shall  liquidate said  Bonds forthwith and
shall not be liable for  any loss so incurred. The  Sponsor may also direct  the
Trustee  to liquidate Bonds in a Trust if the Bonds in the Trust are the subject
of an advanced refunding,  generally considered to be  when refunding bonds  are
issued and the proceeds thereof are deposited in irrevocable trust to retire the
refunded Bonds on their redemption date.
 
    Except  as stated in "COMPOSITION OF  TRUSTS" regarding the limited right of
substitution of Replacement  Bonds for  Failed Bonds, and  except for  refunding
securities that may be exchanged for Bonds under certain conditions specified in
the  Indenture, the Indenture does not permit  either the Sponsor or the Trustee
to acquire or deposit bonds either in  addition to, or in substitution for,  any
of the Bonds initially deposited in a Trust.
 
INFORMATION ABOUT THE TRUSTEE
 
The  Trustee and its address are stated on the  back cover of this Part B of the
Prospectus. The Trustee is subject to supervision and examination by the Federal
Deposit Insurance Corporation,  the Board  of Governors of  the Federal  Reserve
System and either the Comptroller of the Currency or state banking authorities.
 
LIMITATIONS ON LIABILITIES OF SPONSOR AND TRUSTEE
 
    The  Sponsor and the Trustee shall be  under no liability to Unitholders for
taking any action or for  refraining from any action  in good faith pursuant  to
the Indenture, or for errors in judgment, but shall be liable only for their own
negligence,  lack of good faith or willful  misconduct. The Trustee shall not be
liable for depreciation or loss incurred by reason of the sale by the Trustee of
any of the Bonds. In the  event of the failure of  the Sponsor to act under  the
Indenture, the Trustee may act thereunder and shall not be liable for any action
taken by it in good faith under the Indenture.
 
    The  Trustee shall not be liable for any taxes or other governmental charges
imposed upon or in respect of the Bonds or upon the interest thereon or upon  it
as  Trustee under  the Indenture or  upon or in  respect of any  Trust which the
Trustee may be required  to pay under  any present or future  law of the  United
States  of  America or  of any  other taxing  authority having  jurisdiction. In
addition,  the  Indenture  contains  other  customary  provisions  limiting  the
liability of the Trustee.
 
                                       21
<PAGE>
SUCCESSOR TRUSTEES AND SPONSORS
 
    The  Trustee or any successor trustee  may resign by executing an instrument
of resignation in writing and filing same with the Sponsor and mailing a copy of
a notice of resignation to all  Unitholders then of record. Upon receiving  such
notice,  the Sponsor is required to promptly appoint a successor trustee. If the
Trustee becomes incapable of acting or is adjudged a bankrupt or insolvent, or a
receiver or other public officer shall  take charge of its property or  affairs,
the  Sponsor  may  remove  the  Trustee  and  appoint  a  successor  by  written
instrument. The resignation  or removal of  a trustee and  the appointment of  a
successor trustee shall become effective only when the successor trustee accepts
its appointment as such. Any successor trustee shall be a corporation authorized
to  exercise  corporate  trust  powers, having  capital,  surplus  and undivided
profits of not less than $5,000,000. Any corporation into which a trustee may be
merged or with which it may  be consolidated, or any corporation resulting  from
any  merger or consolidation to  which a trustee shall be  a party, shall be the
successor trustee.
 
    If upon resignation  of a trustee  no successor has  been appointed and  has
accepted the appointment within 30 days after notification, the retiring trustee
may  apply  to  a court  of  competent  jurisdiction for  the  appointment  of a
successor.
 
    If the Sponsor fails to undertake any of its duties under the Indenture, and
no express  provision is  made for  action by  the Trustee  in such  event,  the
Trustee  may, in addition to its other  powers under the Indenture (1) appoint a
successor sponsor or (2) terminate the Indenture and liquidate the Trusts.
 
INFORMATION ABOUT THE SPONSOR
 
   
Since our founding  in 1898, Nuveen  has been synonymous  with investments  that
withstand  the  test of  time.  Today, we  offer  a broad  range  of investments
designed for mature investors whose portfolio  is the principal source of  their
ongoing  financial  security. More  than  1.3 million  investors  have entrusted
Nuveen to help them maintain the lifestyle they currently enjoy.
    
 
   
    A value investing  approach--purchasing securities of  strong companies  and
communities  that represent good long-term value--is the cornerstone of Nuveen's
investment philosophy.  It is  a  careful, long-term  strategy that  offers  the
potential for attractive returns with moderated risk. Successful value investing
begins  with in-depth research and a discerning eye for marketplace opportunity.
Nuveen's team of investment professionals is backed by the discipline, resources
and expertise of almost a century of investment experience, including one of the
most recognized research departments in the industry.
    
 
   
    To meet  the unique  circumstances and  financial planning  needs of  mature
investors,  Nuveen  offers  a  wide array  of  taxable  and  tax-free investment
products--including  equity  and   fixed-income  mutual   funds,  unit   trusts,
exchange-traded  funds, customized asset management services and cash management
products. Nuveen is a subsidiary of The  John Nuveen Company which, in turn,  is
approximately  78% owned by the St. Paul  Companies, Inc. ("ST. PAUL"). St. Paul
is located  in St.  Paul,  Minnesota and  is  principally engaged  in  providing
property-liability  insurance through  subsidiaries. Nuveen  is a  member of the
National Association of  Securities Dealers,  Inc. and  the Securities  Industry
Association  and has  its principal office  located in Chicago  (333 West Wacker
Drive). Nuveen maintains 11 regional offices.
    
 
   
    To help advisers and investors better understand and more efficiently use an
investment in  the Trusts  to  reach their  investment  goals, the  Sponsor  may
advertise and create specific investment programs and systems. For example, such
activities may include presenting information on how to use an investment in the
Trusts, alone or in combination with an investment in other mutual funds or unit
investment trusts sponsored by Nuveen, to accumulate assets for future education
needs  or periodic payments such as  insurance premiums. The Trusts' sponsor may
produce software or  additional sales  literature to promote  the advantages  of
using the Trusts to meet these and other specific investor needs.
    
 
OTHER INFORMATION
AMENDMENT OF INDENTURE
 
    The  Indenture may  be amended  by the Trustee  and the  Sponsor without the
consent of any of  the Unitholders (1)  to cure any ambiguity  or to correct  or
supplement  any provision thereof which may be defective or inconsistent, or (2)
to make such  other provisions as  shall not adversely  affect the  Unitholders,
provided,  however, that the Indenture may not be amended to increase the number
of Units in any Trust or to permit the deposit or acquisition of bonds either in
addition to, or in substitution for any of the Bonds initially deposited in  any
Trust except as stated in "COMPOSITION OF TRUSTS" regarding the limited right of
substitution  of Replacement Bonds and except  for the substitution of refunding
bonds under certain circumstances. The  Trustee shall advise the Unitholders  of
any amendment promptly after execution thereof.
 
TERMINATION OF INDENTURE
 
    Each  Trust may be liquidated at any time  by written consent of 100% of the
Unitholders or by  the Trustee when  the value of  such Trust, as  shown by  any
evaluation,  is less than 20% of the original principal amount of such Trust and
will be  liquidated  by  the Trustee  in  the  event that  Units  not  yet  sold
aggregating  more  than 60%  of the  Units originally  created are  tendered for
redemption by the Sponsor thereby reducing the  net worth of such Trust to  less
than  40%  of the  principal amount  of  the Bonds  originally deposited  in the
portfolio. (See "Essential Information" appearing in Part A of this Prospectus.)
The sale of Bonds from the Trusts upon termination may result in realization  of
a  lesser amount than might otherwise be realized if such sale were not required
at such time. For this reason, among others, the amount realized by a Unitholder
 
                                       22
<PAGE>
upon termination  may be  less than  the principal  amount of  Bonds  originally
represented  by the Units held by  such Unitholder. The Indenture will terminate
upon the redemption, sale or other disposition of the last Bond held thereunder,
but in no event shall it continue beyond the end of the calendar year  preceding
the  fiftieth anniversary of its execution for National and State Trusts, beyond
the end  of  the  calendar  year preceding  the  twentieth  anniversary  of  its
execution  for Long Intermediate,  and Intermediate Trusts or  beyond the end of
the calendar year  preceding the tenth  anniversary of its  execution for  Short
Intermediate and Short Term Trusts.
 
   
    Written  notice of  any termination  specifying the  time or  times at which
Unitholders may surrender their Certificates, if any, for cancellation shall  be
given  by  the  Trustee to  each  Unitholder  at the  address  appearing  on the
registration books of  a Trust maintained  by the Trustee.  Within a  reasonable
time  thereafter, the Trustee shall  liquidate any Bonds in  the Trust then held
and shall deduct from  the assets of  the Trust any  accrued costs, expenses  or
indemnities  provided  by  the  Indenture which  are  allocable  to  such Trust,
including estimated compensation of the Trustee and costs of liquidation and any
amounts required as a reserve to provide for payment of any applicable taxes  or
other  governmental charges. The Trustee shall then distribute to Unitholders of
such Trust their pro  rata share of  the balance of  the Interest and  Principal
Accounts.  With such  distribution, the Unitholders  shall be  furnished a final
distribution  statement,  in   substantially  the  same   form  as  the   annual
distribution statement, of the amount distributable. At such time as the Trustee
in  its sole discretion shall determine that  any amounts held in reserve are no
longer necessary, it shall make distribution thereof to Unitholders in the  same
manner.
    
 
LEGAL OPINION
 
    The legality of the Units offered hereby has been passed upon by Chapman and
Cutler, 111 West Monroe Street, Chicago, Illinois 60603. Special counsel for the
Trusts for respective state tax matters are named in "Tax Status" for each Trust
appearing  in  Part A  of this  Prospectus.  Carter, Ledyard  & Milburn,  2 Wall
Street, New York,  New York 10005,  has acted  as counsel for  the Trustee  with
respect  to the Series, and, in the absence of a New York Trust from the Series,
as special New York tax counsel for the Series.
 
AUDITORS
 
    The "Statement  of  Condition" and  "Schedule  of Investments"  at  Date  of
Deposit  included  in Part  A of  this  Prospectus have  been audited  by Arthur
Andersen LLP, independent public  accountants, as indicated  in their report  in
Part  A  of  this Prospectus,  and  are  included herein  in  reliance  upon the
authority of said firm as experts in giving said report.
 
SUPPLEMENTAL INFORMATION
 
    Upon written or telephonic request to the Trustee, investors will receive at
no cost to  the investor supplemental  information about this  Trust, which  has
been  filed  with the  Securities  and Exchange  Commission  and is  intended to
supplement information contained in  Part A and Part  B of this Prospectus.  The
supplemental  information includes more  detailed information concerning certain
of the Bonds included in the Trusts contained in the applicable Series and  more
specific   risk  information  concerning  the   individual  state  Trusts.  This
supplement also includes  additional general information  about the Sponsor  and
the Trusts.
 
                                       23
<PAGE>
                          NUVEEN  Tax-Free Unit Trusts
 
   
                              PROSPECTUS -- PART B
                                  JULY 8, 1997
    
 
   
<TABLE>
<C>                       <S>        <C>
                 SPONSOR             John Nuveen & Co. Incorporated
                                     333 West Wacker Drive
                                     Chicago, IL 60606-1286
                                     Telephone: 312.917.7700
 
                                     Swiss Bank Tower
                                     10 East 50th Street
                                     New York, NY 10022
                                     212.207.2000
 
                 TRUSTEE             The Chase Manhattan Bank
                                     4 New York Plaza
                                     New York, NY 10004-2413
                                     800.257.8787
 
           LEGAL COUNSEL             Chapman and Cutler
              TO SPONSOR             111 West Monroe Street
                                     Chicago, IL 60603
 
             INDEPENDENT             Arthur Andersen LLP
                  PUBLIC             33 West Monroe Street
             ACCOUNTANTS             Chicago, IL 60603
          FOR THE TRUSTS
</TABLE>
    
 
                                 --------------
 
           Except  as to  statements made herein  furnished by  the Trustee, the
Trustee  has  assumed   no  responsibility  for   the  accuracy,  adequacy   and
completeness of the information contained in this Prospectus.
 
           This  Prospectus does not contain all of the information set forth in
the registration  statement  and  exhibits  relating  thereto,  filed  with  the
Securities  and Exchange Commission, Washington,  D.C., under the Securities Act
of 1933, and to which reference is made.
 
   
           No  person  is  authorized  to  give  any  information  or  to   make
representations  not contained in this Prospectus or in supplemental information
or  sales  literature  prepared   by  the  Sponsor,   and  any  information   or
representation  not contained  therein must  not be  relied upon  as having been
authorized by either  the Trusts, the  Trustee or the  Sponsor. This  Prospectus
does  not constitute  an offer to  sell, or a  solicitation of an  offer to buy,
securities in any  State to any  person to whom  it is not  lawful to make  such
offer  in such state. The Trusts are  registered as Unit Investment Trusts under
the Investment Company Act of 1940, as amended. Such registration does not imply
that the  Trusts  or  any  of  their  Units  have  been  guaranteed,  sponsored,
recommended  or approved by the United States  or any State or agency or officer
thereof.
    

<PAGE>
                          NUVEEN TAX-FREE UNIT TRUSTS
 
                 ---------------------------------------------
 
                             INFORMATION SUPPLEMENT
 
                               NUVEEN SERIES 990
 
               This   Information   Supplement   provides  additional
           information concerning the structure, operations and risks
           of  a  Nuveen  Tax-Free  Unit  Trust  not  found  in   the
           prospectuses  for the Trusts.  This Information Supplement
           is not  a  prospectus and  does  not include  all  of  the
           information  that a  prospective investor  should consider
           before investing in a  Trust. This Information  Supplement
           should  be read in conjunction with the prospectus for the
           Trust  in  which  an  investor  is  considering  investing
           ("Prospectus").  Copies of the  Prospectus can be obtained
           by calling or writing the Trustee at the telephone  number
           and  address indicated in  Part B of  the Prospectus. This
           Information Supplement  has  been  created  to  supplement
           information contained in the Prospectus.
 
               This  Information Supplement is  dated March 25, 1998.
           Capitalized terms have been defined in the Prospectus.
 
                               TABLE OF CONTENTS
 
                 ----------------------------------------------
 
   
<TABLE>
<S>                                                                    <C>
GENERAL RISK DISCLOSURE..............................................           2
  Health Care Facility Revenue Obligations...........................           2
  Single Family and Multi-Family Housing Revenue Obligations.........           2
  Single Family Mortgage Revenue Bonds...............................           2
  Congregate Care Revenue Obligations................................           3
  Federally Enhanced Obligations.....................................           3
  Public Housing Authority Revenue Obligations.......................           3
  Industrial Revenue Obligations.....................................           3
  Power Revenue Obligations..........................................           4
  Utility Obligations................................................           4
  Transportation Bonds...............................................           4
  Water and/or Sewerage Revenue Obligations..........................           4
  Resource Recovery Revenue Obligations..............................           5
  Education Revenue Obligations......................................           5
  Bridge and Tollroad Revenue Obligations............................           5
  Dedicated-Tax Supported Revenue Bonds..............................           5
  Municipal Lease Revenue Bonds......................................           5
  Special Obligation to Crossover....................................           5
  Civic Organization Obligations.....................................           5
  Original Issue Discount Bonds and Stripped Obligations.............           5
WHY AND HOW ARE THE BONDS INSURED?...................................           6
ACCUMULATION PLAN....................................................           8
INFORMATION ABOUT THE SPONSOR........................................           9
DESCRIPTION OF RATINGS...............................................          11
HOW THE TRUST COMPARES PERFORMANCE...................................          13
HOW TO CALCULATE YOUR ESTIMATED INCOME...............................          14
Appendix A -- Massachusetts Disclosure...............................         A-1
Appendix B -- New York Disclosure....................................         B-1
Appendix C -- Pennsylvania Disclosure................................         C-1
</TABLE>
    
 
<PAGE>
GENERAL RISK DISCLOSURE
 
    An investment in Units of any Trust should be made with an understanding  of
the  risks that such an investment may  entail. These include the ability of the
issuer, or,  if  applicable,  an  insurer, to  make  payments  of  interest  and
principal  when due, the  effects of changes in  interest rates generally, early
call provisions and the potential for changes in the tax status of the Bonds. As
set forth in the portfolio  summaries in Part A  of this Prospectus, the  Trusts
may  contain or be concentrated  in one or more of  the types of bonds discussed
below.  The  following  paragraphs  discuss  certain  circumstances  which   may
adversely  affect the  ability of issuers  of Bonds  held in the  portfolio of a
Trust to make payment of principal  and interest thereon or which may  adversely
affect  the  ratings of  such Bonds;  with respect  to Insured  Trusts, however,
because of the insurance obtained by the Sponsor or by the issuers of the Bonds,
such changes should not adversely affect an Insured Trust's receipt of principal
and interest, the Standard & Poor's AAA  or Moody's Aaa ratings of the Bonds  in
the Insured Trust portfolio, or the Standard & Poor's AAA rating of the Units of
each  such Insured Trust. For economic  risks specific to the individual Trusts,
see "Risk Factors" for each Trust.
 
    HEALTH CARE FACILITY REVENUE OBLIGATIONS.  Some of the Bonds in a Trust  may
be  obligations of issuers whose revenues  are derived from services provided by
hospitals or other health care  facilities, including nursing homes. Ratings  of
bonds  issued  for health  care facilities  are  sometimes based  on feasibility
studies that contain projections of  occupancy levels, revenues and expenses.  A
facility's  gross  receipts and  net income  available for  debt service  may be
affected by future events and  conditions including, among other things,  demand
for  services, the ability of the facility  to provide the services required, an
increasing shortage of qualified nurses or a dramatic rise in nursing  salaries,
physicians'  confidence  in  the  facility,  management  capabilities,  economic
developments in  the service  area, competition  from other  similar  providers,
efforts  by  insurers  and  governmental agencies  to  limit  rates, legislation
establishing state rate-setting agencies,  expenses, government regulation,  the
cost  and possible unavailability of  malpractice insurance, and the termination
or restriction of governmental  financial assistance, including that  associated
with  Medicare, Medicaid and other similar  third party payor programs. Medicare
reimbursements are currently calculated on a prospective basis and are not based
on a provider's actual costs. Such method of reimbursement may adversely  affect
reimbursements to hospitals and other facilities for services provided under the
Medicare  program and thereby may have an  adverse effect on the ability of such
institutions to satisfy  debt service requirements.  In the event  of a  default
upon  a bond  secured by hospital  facilities, the limited  alternative uses for
such facilities may result  in the recovery upon  such collateral not  providing
sufficient funds to fully repay the bonds.
 
    Certain  hospital  bonds  provide for  redemption  at par  upon  the damage,
destruction or  condemnation of  the  hospital facilities  or in  other  special
circumstances.
 
    SINGLE  FAMILY AND  MULTI-FAMILY HOUSING REVENUE  OBLIGATIONS.   Some of the
Bonds in a  Trust may  be obligations of  issuers whose  revenues are  primarily
derived  from mortgage loans to  housing projects for the  elderly or for low to
moderate income families. Such issues  are generally characterized by  mandatory
redemption  at par or,  in the case  of original issue  discount bonds, accreted
value in the event  of economic defaults and  in the event of  a failure of  the
operator  of a project to  comply with certain covenants  as to the operation of
the project.  The failure  of such  operator to  comply with  certain  covenants
related  to the tax-exempt status  of interest on the  Bonds, such as provisions
requiring that a specified percentage of units be rented or available for rental
to low or  moderate income families,  potentially could cause  interest on  such
Bonds  to be subject to Federal income taxation from the date of issuance of the
Bonds. The  ability  of such  issuers  to make  debt  service payments  will  be
affected  by events and conditions affecting financed projects, including, among
other things, the achievement and maintenance of sufficient occupancy levels and
adequate rental income,  employment and  income conditions  prevailing in  local
labor  markets, increases in taxes, utility  costs and other operating expenses,
the managerial ability  of project  managers, changes in  laws and  governmental
regulations,  the  appropriation of  subsidies, and  social and  economic trends
affecting the localities in  which the projects are  located. Occupancy of  such
housing  projects  may be  adversely  affected by  high  rent levels  and income
limitations imposed under Federal and state programs.
 
    SINGLE FAMILY MORTGAGE REVENUE BONDS.  Some  of the Bonds in a Trust may  be
single  family  mortgage revenue  bonds,  which are  issued  for the  purpose of
acquiring from originating financial institutions notes secured by mortgages  on
residences located within the issuer's boundaries and owned by persons of low or
moderate  income. Mortgage loans  are generally partially  or completely prepaid
prior to  their final  maturities as  a result  of events  such as  sale of  the
mortgaged  premises, default, condemnation or casualty loss. Because these bonds
are subject to extraordinary mandatory redemption in whole or in part from  such
prepayments of mortgage loans, a substantial portion of such bonds will probably
be  redeemed prior to their scheduled maturities or even prior to their ordinary
call dates. Extraordinary mandatory redemption without premium could also result
from the  failure of  the originating  financial institutions  to make  mortgage
loans in sufficient amounts within a specified time period. The redemption price
of  such issues  may be  more or  less than  the offering  price of  such bonds.
Additionally, unusually high rates of  default on the underlying mortgage  loans
may  reduce revenues available  for the payment  of principal of  or interest on
such mortgage revenue
 
                                       2
<PAGE>
bonds. Single family mortgage revenue bonds issued after December 31, 1980  were
issued  under Section 103A of the Internal  Revenue Code of 1954, as amended, or
Section 143 of the Internal Revenue Code of 1986, which Sections contain certain
requirements relating to the use of the proceeds of such bonds in order for  the
interest on such bonds to retain its tax-exempt status. In each case, the issuer
of  the bonds  has covenanted  to comply  with applicable  requirements and bond
counsel to such issuer has issued an  opinion that the interest on the bonds  is
exempt from Federal income tax under existing laws and regulations. There can be
no assurance that such continuing requirements will be satisfied; the failure to
meet  such  requirements could  cause interest  on  the Bonds  to be  subject to
Federal income taxation, possibly from the date of issuance of the Bonds.
 
    CONGREGATE CARE REVENUE OBLIGATIONS.   Some of the Bonds  in a Trust may  be
obligations  of  issuers  whose revenues  are  primarily derived  from  loans to
finance the  construction  and/or  acquisition of  congregate  care  facilities,
including  retirement  facilities and  nursing  care units.  A  facility's gross
receipts and net  income available for  debt service may  be affected by  future
events  and conditions, including, among other  things, demand for services, the
ability  of  the   facility  to  provide   the  services  required,   management
capabilities,  an increasing shortage of qualified  nurses or a dramatic rise in
nursing salaries, economic  developments in the  service area, competition  from
other  similar providers, efforts by insurers and governmental agencies to limit
rates,  legislation   establishing   state  rate-setting   agencies,   expenses,
government  regulation  and  the  termination  or  restriction  of  governmental
financial assistance.
 
    FEDERALLY ENHANCED  OBLIGATIONS.   Some of  the mortgages  which secure  the
various  health care or housing projects which underlie the previously discussed
Health Care Facility  Revenue, Single Family  and Multi-Family Housing  Revenue,
Single  Family Mortgage  Revenue Obligations  and Congregate  Care Revenue Bonds
(the  "Obligations")  in  a  Trust  may  be  insured  by  the  Federal   Housing
Administration  ("FHA"). Under  FHA regulations, the  maximum insurable mortgage
amount cannot exceed 90% of  the FHA's estimated value  of the project. The  FHA
mortgage  insurance does  not constitute  a guarantee  of timely  payment of the
principal of  and interest  on the  Obligations. Payment  of mortgage  insurance
benefits may be (1) less than the principal amount of Obligations outstanding or
(2)  delayed if  disputes arise as  to the amount  of the payment  or if certain
notices are  not  given  to the  FHA  within  the prescribed  time  periods.  In
addition,  some  of  the  previously discussed  Obligations  may  be  secured by
mortgage-backed certificates  guaranteed  by the  Government  National  Mortgage
Association  ("GNMA"), a  wholly owned  corporate instrumentality  of the United
States, and/or  the  Federal  National Mortgage  Association  ("Fannie  Mae")  a
federally  chartered  and  stockholder-owed  corporation.  GNMA  and  Fannie Mae
guarantee timely  payment  of  principal and  interest  on  the  mortgage-backed
certificates,  even where the  underlying mortgage payments  are not made. While
such mortgage-backed  certificates  are  often  pledged  to  secure  payment  of
principal  and  interest  on the  Obligations,  timely payment  of  interest and
principal on the Obligations is not insured or guaranteed by the United  States,
GNMA,  Fannie Mae or any other  governmental agency or instrumentality. The GNMA
mortgage-backed certificates  constitute  a  general obligation  of  the  United
States  backed by  its full  faith and  credit. The  obligations of  Fannie Mae,
including its obligations under the  Fannie Mae mortgage-backed securities,  are
obligations solely of Fannie Mae and are not backed by, or entitled to, the full
faith and credit of the United States.
 
    PUBLIC  HOUSING AUTHORITY REVENUE OBLIGATIONS.  Some of the Bonds in a Trust
may be obligations of issuers whose revenues are primarily derived from loans to
finance public  housing projects.  These  bonds are  guaranteed by  the  federal
Department   of  Housing  and  Urban  Development.  Such  issues  are  generally
characterized by mandatory redemption at par  or, in the case of original  issue
discount bonds, accreted value in the event of economic defaults. The ability of
such  issuers  to make  debt service  payments  will be  affected by  events and
conditions affecting  financed  projects,  including, among  other  things,  the
achievement  and  maintenance  of sufficient  occupancy  levels,  employment and
income conditions prevailing in local labor markets, increases in taxes, utility
costs  and  other   operating  expenses,  changes   in  laws  and   governmental
regulations,  and social and  economic trends affecting  the localities in which
the projects are  located. In addition,  the federal Department  of Housing  and
Urban  Development may impose  regulations and/or limitations  which may have an
adverse impact on the Bonds in a Trust.
 
    INDUSTRIAL REVENUE OBLIGATIONS.   Certain  of the Bonds  in a  Trust may  be
industrial  revenue bonds  ("IRBs"), which  are tax-exempt  securities issued by
states, municipalities, public  authorities or similar  entities to finance  the
cost  of acquiring, constructing or improving various industrial projects. These
projects are usually operated by corporate entities. Issuers are obligated  only
to  pay amounts due on the IRBs to  the extent that funds are available from the
unexpended proceeds of the IRBs or receipts  or revenues of the issuer under  an
arrangement  between the  issuer and  the corporate  operator of  a project. The
arrangement may  be  in  the  form  of  a  lease,  installment  sale  agreement,
conditional  sale agreement or loan agreement, but  in each case the payments to
the issuer are designed to be sufficient to meet the payments of amounts due  on
the  IRBs. Regardless of the structure, payment of IRBs is solely dependent upon
the  creditworthiness  of  the  corporate  operator  of  the  project  and,   if
applicable,  corporate  guarantor.  Corporate  operators  or  guarantors  may be
affected by many factors which may have an adverse impact on the credit  quality
of the particular company or industry. These include cyclicality of revenues and
earnings,  regulatory and environmental  restrictions, litigation resulting from
accidents  or  environmentally-caused   illnesses,  extensive  competition   and
financial  deterioration resulting from a  corporate restructuring pursuant to a
leveraged  buy-out,   takeover   or   otherwise.  Such   a   restructuring   may
 
                                       3
<PAGE>
result  in the operator of a project becoming highly leveraged which may have an
impact on such operator's creditworthiness which  in turn would have an  adverse
impact on the rating and/or market value of such Bonds. Further, the possibility
of  such  a restructuring  may  have an  adverse impact  on  the market  for and
consequently the value of  such Bonds, even though  no actual takeover or  other
action  is ever contemplated or effected. The IRBs  in a Trust may be subject to
special or extraordinary redemption provisions which may provide for  redemption
at  par or, in  the case of  original issue discount  bonds, accreted value. The
Sponsor cannot predict the causes or likelihood  of the redemption of IRBs in  a
Trust prior to the stated maturity of such Bonds.
 
    POWER  REVENUE OBLIGATIONS.  Some of the Bonds in a Trust may be obligations
of issuers whose revenues are primarily derived from pollution control bonds  as
well  as the sale of electric energy and  oil and gas. Some of these obligations
are backed by the credit of an investor owned utility (IOU). The problems  faced
by  such issuers  include the  difficulty in  obtaining approval  for timely and
adequate rate  increases from  the applicable  public utility  commissions,  the
difficulty  of  financing  large construction  programs,  increased competition,
reductions in estimates of future demand for electricity in certain areas of the
country,  the  limitations  on  operations   and  increased  costs  and   delays
attributable  to  environmental considerations,  the  difficulty of  the capital
market in absorbing utility debt, the difficulty in obtaining fuel at reasonable
prices and the  effect of  energy conservation. All  of such  issuers have  been
experiencing certain of these problems in varying degrees. In addition, Federal,
state  and  municipal  governmental authorities  may  from time  to  time review
existing,  and   impose  additional,   regulations  governing   the   licensing,
construction  and operation of nuclear power  plants, which may adversely affect
the ability of the issuers of certain of  the Bonds in a Trust to make  payments
of principal and/or interest on such Bonds.
 
    UTILITY  OBLIGATIONS.  Some  of the Bonds  in a Trust  may be obligations of
issuers whose revenues are primarily derived from the sale of natural gas or the
combined net revenue  of two or  more municipal utility  systems operating as  a
single  entity. The  problems faced  by such  issuers include  the difficulty in
obtaining approval for timely  and adequate rate  increases from the  applicable
public  utility  commissions,  the difficulty  of  financing  large construction
programs, increased competition, reductions in  estimates of future demands  for
natural  gas in certain areas of the  country, the limitations on operations and
increased costs  and delays  attributable to  environmental considerations,  the
difficulty  of the capital  market in absorbing utility  debt, the difficulty in
obtaining fuel at reasonable  prices and the effect  of energy conservation.  In
addition, Federal, state and municipal governmental authorities may from time to
time   review  existing,  and  impose   additional,  regulations  governing  the
licensing, construction  and  operation  of  nuclear  power  plants,  which  may
adversely  affect the ability of the issuers of  certain of the Bonds in a Trust
to make payments of principal and/or interest on such Bonds.
 
    TRANSPORTATION BONDS.  Some of  the Bonds in a  Trust may be obligations  of
issuers  which  are  payable  from  and secured  by  revenues  derived  from the
ownership and operation of airports, public transit systems and ports. The major
portion of an airport's  gross operating income is  generally derived from  fees
received  from  airlines  pursuant to  use  agreements which  consist  of annual
payments for airport use, occupancy of certain terminal space, service fees  and
leases. Airport operating income may therefore be affected by the ability of the
airlines  to meet their obligations under  the use agreements. The air transport
industry is experiencing significant variations in earnings and traffic, due  to
increased  competition, excess capacity,  increased costs, deregulation, traffic
constraints and  other factors,  and several  airlines are  experiencing  severe
financial  difficulties. In particular, facilities with use agreements involving
airlines experiencing financial difficulty may experience a reduction in revenue
due to the  possible inability  of these airlines  to meet  their use  agreement
obligations  because of such financial difficulties and possible bankruptcy. The
Sponsor cannot predict what effect these industry conditions may have on airport
revenues which  are dependent  for payment  on the  financial condition  of  the
airlines  and their  usage of  the particular  airport facility.  Bonds that are
secured primarily by the revenue collected by a public transit system  typically
are  additionally secured  by a  pledge of sales  tax receipts  collected at the
state or local  level, or  of other governmental  financial assistance.  Transit
system net revenues will be affected by variations in utilization, which in turn
may  be affected by the degree  of local governmental subsidization, demographic
and population shifts, and competition  from other forms of transportation;  and
by  increased  costs,  including  costs  resulting  from  previous  deferrals of
maintenance. Port authorities derive their revenues primarily from fees  imposed
on  ships using the facilities.  The rate of utilization  of such facilities may
fluctuate depending on the local economy and on competition from competing forms
of transportation such as air, rail and trucks.
 
    WATER AND/OR SEWERAGE REVENUE OBLIGATIONS.  Some of the Bonds in a Trust may
be obligations of  issuers whose  revenues are derived  from the  sale of  water
and/or  sewerage services. Such Bonds are  generally payable from user fees. The
problems of such issuers include the ability to obtain timely and adequate  rate
increases,  population decline resulting in  decreased user fees, the difficulty
of financing  large construction  programs, the  limitations on  operations  and
increased  costs and  delays attributable  to environmental  considerations, the
increasing difficulty of obtaining or  discovering new supplies of fresh  water,
the  effect  of  conservation  programs and  the  impact  of  "no-growth" zoning
ordinances. All of such issuers have been experiencing certain of these problems
in varying degrees.
 
                                       4
<PAGE>
    RESOURCE RECOVERY REVENUE OBLIGATIONS.  Some of the Bonds in a Trust may  be
obligations  of issuers whose revenues are derived  from the sale of sewerage or
solid waste disposal services. Such bonds are generally payable from user  fees.
The  problems of such issuers include the  ability to obtain timely and adequate
rate increases,  population  decline  resulting  in  decreased  user  fees,  the
difficulty   of  financing  large  construction  programs,  the  limitations  on
operations  and  increased  costs  and  delays  attributable  to   environmental
considerations,   the  effect  of  conservation   programs  and  the  impact  of
"no-growth" zoning  ordinances.  All  of such  issuers  have  been  experiencing
certain of these problems in varying degrees.
 
    EDUCATION  REVENUE  OBLIGATIONS.   Some  of  the  Bonds in  a  Trust  may be
obligations of issuers which are, or which govern the operation of, colleges and
universities and  whose  revenues are  derived  mainly from  tuition,  dormitory
revenues,  grants and endowments.  General problems of  such issuers include the
prospect of a declining percentage of the population consisting of "college" age
individuals, possible inability to raise tuitions and fees sufficiently to cover
increased operating  costs,  the uncertainty  of  continued receipt  of  Federal
grants  and state funding,  and government legislation  or regulations which may
adversely affect the revenues or costs of such issuers. All of such issuers have
been experiencing certain of these problems in varying degrees.
 
    BRIDGE AND TOLLROAD REVENUE OBLIGATIONS.  Some  of the Bonds in a Trust  may
be  obligations  of issuers  which derive  their payments  from bridge,  road or
tunnel toll revenues. The revenues of such an issuer could be adversely affected
by competition from toll-free vehicular bridges and roads and alternative  modes
of transportation. Such revenues could also be adversely affected by a reduction
in  the availability of fuel to motorists  or significant increases in the costs
thereof. Specifically, governmental regulations restricting the use of  vehicles
in  the New  York City  metropolitan area may  adversely affect  revenues of the
Triborough Bridge and Tunnel Authority.
 
    DEDICATED-TAX SUPPORTED REVENUE BONDS.  Some of the Bonds in a Trust may  be
obligations of issuers which are payable from and secured by tax revenues from a
designated  source, which revenues are pledged  to secure the bonds. The various
types of  Bonds described  below differ  in structure  and with  respect to  the
rights of the bondholders to the underlying property. Each type of dedicated-tax
supported  Bond has distinct risks, only some  of which are set forth below. One
type of dedicated-tax supported Bond is secured by the incremental tax  received
on  either real property or on  sales within a specifically defined geographical
area; such  tax  generally will  not  provide bondholders  with  a lien  on  the
underlying property or revenues. Another type of dedicated-tax supported Bond is
secured  by a special tax levied on  real property within a defined geographical
area in such  a manner  that the tax  is levied  on those who  benefit from  the
project;  such bonds  typically provide for  a statutory lien  on the underlying
property for unpaid taxes. A third  type of dedicated-tax supported Bond may  be
secured by a tax levied upon the manufacture, sale or consumption of commodities
or  upon the license to pursue  certain occupations or upon corporate privileges
within a taxing jurisdiction. As to any of these types of Bonds, the ability  of
the  designated revenues to satisfy the  interest and principal payments on such
bonds may be affected by changes in the local economy, the financial success  of
the  enterprise  responsible for  the payment  of  the taxes,  the value  of any
property on which taxes may be assessed and the ability to collect such taxes in
a timely fashion. Each  of these factors  will have a  different affect on  each
distinct type of dedicated-tax supported bonds.
 
    MUNICIPAL  LEASE  REVENUE  BONDS.   Some  of the  Bonds  in a  Trust  may be
obligations that are secured  by lease payments of  a governmental entity.  Such
payments  are normally  subject to annual  budget appropriations  of the leasing
governmental entity.  A  governmental  entity  that enters  into  such  a  lease
agreement  cannot obligate future governments to  appropriate for and make lease
payments but covenants to take such action as is necessary to include any  lease
payments  due  in  its  budgets  and  to  make  the  appropriations  therefor. A
governmental entity's failure to appropriate for and to make payments under  its
lease obligation could result in insufficient funds available for payment of the
obligations secured thereby.
 
    SPECIAL OBLIGATION TO CROSSOVER.  Some of the Bonds in a Trust may be issued
with the intention of crossover refunding an outstanding issue at a future date.
These  bonds are  secured to  the crossover  date by  U.S. Government securities
purchased with the  proceeds of  the refunding bonds.  The revenues  of such  an
issuer  could be adversely affected by  problems associated with the outstanding
issue, economic, social and environmental  policies and conditions that are  not
within  the  control of  the issuer  and  governmental policies  and regulations
affecting the issuer.
 
    CIVIC ORGANIZATION  OBLIGATIONS.   Some  of  the Bonds  in  a Trust  may  be
obligations  of  issuers whose  revenues are  derived from  the pledge  of civic
organizations, including  their  assets.  The problems  faced  by  such  issuers
include  the ability  to collect  pledges made,  the unpredictable  nature of an
organization's  composition  and  participation,   the  quality  and  skill   of
management,  increased costs and delays attributable to organizations, expenses,
and legislation regarding certain organizational purposes.
 
    ORIGINAL ISSUE  DISCOUNT BONDS  AND STRIPPED  OBLIGATIONS.   Certain of  the
Bonds  in a Trust may be original  issue discount bonds. These Bonds were issued
with nominal  interest rates  less than  the rates  then offered  by  comparable
securities  and as a consequence  were originally sold at  a discount from their
face, or par, values. This original  issue discount, the difference between  the
initial  purchase price and face value, is deemed under current law to accrue on
a
 
                                       5
<PAGE>
daily basis and the accrued portion is treated as tax-exempt interest income for
federal income tax purposes.  On sale or redemption,  gain, if any, realized  in
excess  of the  earned portion  of original  issue discount  will be  taxable as
capital gain. See "What is the Tax Status of Unitholders". The current value  of
an original issue discount bond reflects the present value of its face amount at
maturity. In a stable interest rate environment, the market value of an original
issue  discount bond would  tend to increase  more slowly in  early years and in
greater increments as the bond approached maturity.
 
    Certain of the original issue discount bonds  in a Trust may be zero  coupon
bonds. Zero coupon bonds do not provide for the payment of any current interest;
the  buyer receives only the right to receive a final payment of the face amount
of the bond at its maturity. The effect  of owning a zero coupon bond is that  a
fixed  yield is earned not only on  the original investment but also, in effect,
on all  discount  earned  during  the life  of  the  obligation.  This  implicit
reinvestment of earnings at the same rate eliminates the risk of being unable to
reinvest  the income on such obligation at a rate as high as the implicit yield,
but at the same time also eliminates the holder's ability to reinvest at  higher
rates  in  the  future.  For  this reason,  zero  coupon  bonds  are  subject to
substantially greater  price  fluctuations  during periods  of  changing  market
interest  rates  than are  securities of  comparable  quality that  pay interest
currently.
 
    Original issue discount bonds, including  zero coupon bonds, may be  subject
to  redemption at prices  based on the  issue price plus  the amount of original
issue  discount  accreted  to  redemption   (the  "accreted  value")  plus,   if
applicable,  some premium.  Pursuant to such  call provisions  an original issue
discount bond may be called prior to its maturity date at a price less than  its
face  value. See the  "Schedules of Investments" for  more information about the
call provisions of portfolio Bonds.
 
    Certain of the Bonds in a Trust may be Stripped Obligations, which represent
evidences of  ownership with  respect to  either the  principal amount  of or  a
payment  of interest on a tax-exempt  obligation. An obligation is "stripped" by
depositing it with  a custodian, which  then effects a  separation in  ownership
between  the bond and any interest payment which has not yet become payable, and
issues evidences of ownership with respect to such constituent parts. A Stripped
Obligation therefore has economic characteristics similar to zero coupon  bonds,
as described above.
 
    Each  Stripped Obligation has  been purchased at a  discount from the amount
payable at maturity. With respect to each Unitholder, the Internal Revenue  Code
treats  as "original issue discount" that portion of the discount which produces
a yield to maturity (as of the date of purchase of the Unitholder's Units) equal
to the lower of the coupon rate of interest on the underlying obligation or  the
yield  to maturity on the basis of  the purchase price of the Unitholder's Units
which is allocable to  each Stripped Obligation.  Original issue discount  which
accrues with respect to a Stripped Obligation will be exempt from Federal income
taxation  to the  same extent  as interest  on the  underlying obligations. (See
"WHAT IS THE TAX STATUS OF UNITHOLDERS?" in Part B of this Prospectus.)
 
    Unitholders should consult their own tax advisers with respect to the  state
and  local tax consequences of owning  original issue discount bonds or Stripped
Obligations. Under applicable  provisions governing determination  of state  and
local  taxes, interest on original issue  discount bonds or Stripped Obligations
may be deemed  to be received  in the year  of accrual even  though there is  no
corresponding cash payment.
 
WHY AND HOW ARE THE BONDS INSURED?
 
INSURANCE ON BONDS
 
INSURED  TRUSTS--The Insurer's policy unconditionally and irrevocably guarantees
the full and complete payment required to be made by or on behalf of the  Issuer
to  the Paying Agent or its successor of an amount equal to (i) the principal of
(either at the stated maturity  or by an advancement  of maturity pursuant to  a
mandatory  sinking fund  payment) and  interest on,  the Bonds  as such payments
shall become due  but shall  not be so  paid (except  that in the  event of  any
acceleration  of  the due  date  of such  principal  by reason  of  mandatory or
optional redemption or acceleration resulting  from default or otherwise,  other
than  any advancement of maturity pursuant  to a mandatory sinking fund payment,
the payments guaranteed by  the Insurer's policy shall  be made in such  amounts
and  at such times as  such payments of principal would  have been due had there
not been any such acceleration); and (ii) the reimbursement of any such  payment
which  is subsequently recovered from any owner of the Bonds pursuant to a final
judgment by a court of competent  jurisdiction that such payment constitutes  an
avoidable  preference  to  such  owner  within  the  meaning  of  any applicable
bankruptcy law (a "Preference").
 
    The Insurer's policy does not insure against loss of any prepayment  premium
which  may at any time be payable with respect to any Bond. The Insurer's policy
does not, under any circumstance, insure against loss relating to: (i)  optional
or  mandatory redemptions (other than  mandatory sinking fund redemptions); (ii)
any payments to be made on an accelerated basis; (iii) payments of the  purchase
price  of Bonds upon tender by an owner thereof; or (iv) any Preference relating
to (i) through (iii)  above. The Insurer's policy  also does not insure  against
nonpayment  of  principal  of  or  interest  on  the  Bonds  resulting  from the
insolvency, negligence or any other act or  omission of the Paying Agent or  any
other paying agent for the Bonds.
 
                                       6
<PAGE>
    Upon  receipt of telephonic or  telegraphic notice, such notice subsequently
confirmed in writing by registered or certified mail, or upon receipt of written
notice by registered or certified mail, by the Insurer from the Paying Agent  or
any owner of a Bond the payment of an insured amount for which is then due, that
such  required payment has  not been made, the  Insurer on the  due date of such
payment or within one business day  after receipt of notice of such  nonpayment,
whichever  is later,  will make  a deposit  of funds,  in an  account with State
Street Bank and Trust Company,  N.A., in New York,  New York, or its  successor,
sufficient  for the payment of any such insured amounts which are then due. Upon
presentment and surrender of  such Bonds or presentment  of such other proof  of
ownership  of the Bonds, together with any appropriate instruments of assignment
to evidence the assignment of the insured  amounts due on the Bonds as are  paid
by  the Insurer,  and appropriate instruments  to effect the  appointment of the
Insurer as agent for such owners of the Bonds in any legal proceeding related to
payment of  insured amounts  on the  Bonds,  such instruments  being in  a  form
satisfactory to State Street Bank and Trust Company, N.A., State Street Bank and
Trust Company, N.A. shall disperse to such owners or the Paying Agent payment of
the  insured amounts due on such Bonds, less any amount held by the Paying Agent
for the payment of such insured amounts and legally available therefor.
 
    The Insurer is the principal operating subsidiary of MBIA, Inc., a New  York
Stock  Exchange listed company  (the "Company"). MBIA, Inc.  is not obligated to
pay the debts of or claims against the Insurer. The Insurer is domiciled in  the
State of New York and licensed to do business in and subject to regulation under
the  laws of all 50 states, the District of Columbia, the Commonwealth of Puerto
Rico, the Commonwealth of  the Northern Mariana Islands,  the Virgin Islands  of
the  United  States and  the Territory  of  Guam. The  Insurer has  two European
branches, one in the Republic of France  and the other in the Kingdom of  Spain.
New York has laws prescribing minimum capital requirements, limiting classes and
concentrations  of investments  and requiring the  approval of  policy rates and
forms. State laws also regulate the amount of both the aggregate and  individual
risks  that may be insured, the payment  of dividends by the Insurer, changes in
control and transactions among affiliates. Additionally, the Insurer is required
to maintain contingency reserves on its  liabilities in certain amounts and  for
certain periods of time.
 
    Effective  February 17,  1998, the Company  acquired all  of the outstanding
stock of Capital Markets  Assurance Corporation ("CMAC"),  a New York  domiciled
financial  guarantee insurance company, through a merger with its parent, CapMAC
Holdings, Inc. The  Company then  contributed the common  stock of  CMAC to  the
Insurer.  Pursuant to  a reinsurance  agreement, CMAC has  ceded all  of its net
insured risks as well as its  unearned premiums and contingency reserves to  the
Insurer  and  the Insurer  has reinsured  CMAC's  net outstanding  exposure. The
Company is not obligated to pay the debts of or claims against CMAC.
 
    As of December  31, 1996  the Insurer had  admitted assets  of $4.4  billion
(audited),  total liabilities of  $3.0 billion (audited),  and total capital and
surplus of  $1.4  billion  (audited) determined  in  accordance  with  statutory
accounting   practices   prescribed   or  permitted   by   insurance  regulatory
authorities. As of September 30, 1997,  the Insurer had admitted assets of  $5.1
billion  (unaudited), total liabilities  of $3.4 billion  (unaudited), and total
capital and surplus of  $1.7 billion (unaudited)  determined in accordance  with
statutory  accounting practices prescribed or  permitted by insurance regulatory
authorities.
 
    Furthermore, copies of the Insurer's year end financial statements  prepared
in  accordance with statutory accounting  practices are available without charge
from the Insurer.  A copy of  the Annual Report  on Form 10-K  of MBIA, Inc.  is
available  from  the  Insurer or  the  Securities and  Exchange  Commission. The
address of the Insurer is 113 King Street, Armonk, New York 10504. The telephone
number of the Insurer is (914) 273-4545.
 
    Moody's Investors Service rates the claims paying ability of the Insurer and
CMAC "Aaa".
 
    Standard & Poor's Ratings Service, a division of the McGraw Hill  Companies,
Inc., rates the claims paying ability of the Insurer and CMAC "AAA".
 
   
    Fitch IBCA, Inc. (formerly known as Fitch Investors Service, L.P.) rates the
claims  paying ability of  the Insurer "AAA."  (CMAC has not  requested a rating
from Fitch IBCA, Inc.)
    
 
    Each rating of the  Insurer should be  evaluated independently. The  ratings
reflect   the   respective   rating   agency's   current   assessment   of   the
creditworthiness of the Insurer and its ability to pay claims on its policies of
insurance. Any further explanation as to  the significance of the above  ratings
may be obtained only from the applicable rating agency.
 
    The  above ratings are not  recommendations to buy, sell  or hold the Bonds,
and such ratings may  be subject to  revision or withdrawal at  any time by  the
rating agencies. Any downward revision or withdrawal of any of the above ratings
may  have an adverse effect  on the market price of  the Bonds. The Insurer does
not guaranty the market price of the Bonds nor does it guaranty that the ratings
on the Bonds will not be revised or withdrawn.
 
TRADITIONAL TRUSTS--Insurance guaranteeing the timely payment, when due, of  all
principal  and interest on  certain Bonds in  a Traditional Trust  may have been
obtained by the Sponsor, issuer or underwriter of the particular Bonds  involved
or  by another party. Such insurance,  which provides coverage substantially the
same as  that obtained  with respect  to Bonds  in Insured  Trusts as  described
above,  is  effective  so  long  as the  insured  Bond  is  outstanding  and the
 
                                       7
<PAGE>
insurer remains in business. Insurance relates  only to the particular Bond  and
not  to the Units  offered hereby or  to their market  value. Insured Bonds have
received a rating of  "Aaa" by Moody's Investors  Service, Inc. and/or "AAA"  by
Standard & Poor's Corporation in recognition of such insurance.
 
    If  a Bond in a Traditional Trust is insured, the Schedule of Investments in
Part A of  this Prospectus  will identify the  insurer. Such  insurance will  be
provided  by  Financial  Guaranty Insurance  Company  ("FGIC"),  AMBAC Assurance
Corporation ("AMBAC"), Bond Investors Guaranty  Insurance Company, now known  as
MBIA  Corp. of  Illinois ("BIG"),  Capital Guaranty  Insurance Company ("CGIC"),
Financial Security Assurance, Inc. ("FSA"), Municipal Bond Insurance Association
(the "Association"), MBIA Insurance Corporation ("MBIA") or Connie Lee Insurance
Company ("ConnieLee"). The Sponsor to  date has purchased and presently  intends
to purchase insurance for Bonds in Traditional Trusts exclusively from MBIA (see
the  preceding disclosure  regarding MBIA). There  can be no  assurance that any
insurer listed therein  will be  able to satisfy  its commitments  in the  event
claims  are made in the future. However, Standard & Poor's Corporation has rated
the claims-paying ability of each  insurer "AAA," and Moody's Investors  Service
has  rated  all bonds  insured by  each such  insurer, except  ConnieLee, "Aaa."
Moody's Investor's Service gives no ratings for bonds insured by ConnieLee.
 
    Because any such insurance  will be effective so  long as the insured  Bonds
are  outstanding, such insurance  will be taken into  account in determining the
market value  of  such Bonds  and  therefore  some value  attributable  to  such
insurance  will be included in the value of the Units of the Trust that includes
such Bonds. The insurance does not,  however, guarantee the market value of  the
Bonds or of the Units.
 
ACCUMULATION PLAN
 
The  Sponsor, John Nuveen & Co.  Incorporated, is also the principal underwriter
of the Accumulation Funds listed in the following table. Each of these funds  is
an  open-end, diversified  management investment company  into which Unitholders
may choose  to reinvest  Trust distributions  automatically, without  any  sales
charge.  Unitholders may reinvest  both interest and  principal distributions or
principal distributions only. Each  Accumulation Fund has investment  objectives
which  differ in  certain respects from  those of  the Trusts and  may invest in
securities which would not be eligible for deposit in the Trusts. The investment
adviser to each Accumulation Fund is  a wholly-owned subsidiary of the  Sponsor.
Unitholders  should contact their financial adviser  or the Sponsor to determine
which of  the Accumulation  Funds they  may reinvest  into, as  reinvestment  in
certain of the Accumulation Funds may be restricted to residents of a particular
state  or states. Unitholders may obtain a prospectus for each Accumulation Fund
through their financial adviser or through the Sponsor at (800) 621-7227. For  a
more  detailed  description,  Unitholders  should  read  the  prospectus  of the
Accumulation Fund in which they are interested.
 
The following is a complete list of the Accumulation Funds currently  available,
as  of  the  Date  of  Deposit of  this  Prospectus,  to  Unitholders  under the
Accumulation Plan. The list of available Accumulation Funds is subject to change
without the consent of any of the Unitholders.
 
ACCUMULATION FUNDS
 
MUTUAL FUNDS
 
NUVEEN FLAGSHIP MUNICIPAL TRUST
 
      Nuveen Municipal Bond Fund
      Nuveen Insured Municipal Bond Fund
      Nuveen Flagship All-American Municipal Bond Fund
      Nuveen Flagship Limited Term Municipal Bond Fund
      Nuveen Flagship Intermediate Municipal Bond Fund
 
NUVEEN FLAGSHIP MULTISTATE TRUST I
 
      Nuveen Flagship Arizona Municipal Bond Fund
      Nuveen Flagship Colorado Municipal Bond Fund
      Nuveen Flagship Florida Municipal Bond Fund
      Nuveen Flagship Florida Intermediate Municipal Bond Fund
      Nuveen Maryland Municipal Bond Fund
      Nuveen Flagship New Mexico Municipal Bond Fund
      Nuveen Flagship Pennsylvania Municipal Bond Fund
      Nuveen Flagship Virginia Municipal Bond Fund
 
NUVEEN FLAGSHIP MULTISTATE TRUST II
 
      Nuveen California Municipal Bond Fund
      Nuveen California Insured Municipal Bond Fund
 
                                       8
<PAGE>
      Nuveen Flagship Connecticut Municipal Bond Fund
      Nuveen Massachusetts Municipal Bond Fund
      Nuveen Massachusetts Insured Municipal Bond Fund
      Nuveen Flagship New Jersey Municipal Bond Fund
      Nuveen Flagship New Jersey Intermediate Municipal Bond Fund
      Nuveen Flagship New York Municipal Bond Fund
      Nuveen New York Insured Municipal Bond Fund
 
NUVEEN FLAGSHIP MULTISTATE TRUST III
 
      Nuveen Flagship Alabama Municipal Bond Fund
      Nuveen Flagship Georgia Municipal Bond Fund
      Nuveen Flagship Louisiana Municipal Bond Fund
      Nuveen Flagship North Carolina Municipal Bond Fund
      Nuveen Flagship South Carolina Municipal Bond Fund
      Nuveen Flagship Tennessee Municipal Bond Fund
 
NUVEEN FLAGSHIP MULTISTATE TRUST IV
 
      Nuveen Flagship Kansas Municipal Bond Fund
      Nuveen Flagship Kentucky Municipal Bond Fund
      Nuveen Flagship Kentucky Limited Term Municipal Bond Fund
      Nuveen Flagship Michigan Municipal Bond Fund
      Nuveen Flagship Missouri Municipal Bond Fund
      Nuveen Flagship Ohio Municipal Bond Fund
      Nuveen Flagship Wisconsin Municipal Bond Fund
 
Flagship Utility Income Fund
 
Nuveen Growth and Income Stock Fund
 
Nuveen Balanced Stock and Bond Fund
 
Nuveen Balanced Municipal and Stock Fund
 
   
Nuveen Rittenhouse Growth Fund
    
 
MONEY MARKET FUNDS
 
Nuveen California Tax-Free Money Market Fund
 
Nuveen Massachusetts Tax-Free Money Market Fund
 
Nuveen New York Tax-Free Money Market Fund
 
Nuveen Tax-Free Reserves, Inc.
 
Nuveen Tax-Exempt Money Market Fund, Inc.
 
    Each person who purchases Units of a  Trust may become a participant in  the
Accumulation  Plan and elect  to have his  or her distributions  on Units of the
Trust invested directly in shares of one of the Accumulation Funds.  Reinvesting
Unitholders   may  select  any  interest  distribution  plan.  Thereafter,  each
distribution  of  interest  income  or  principal  on  the  participant's  Units
(principal  only in  the case of  a Unitholder  who has chosen  to reinvest only
principal distributions) will, on the applicable distribution date, or the  next
day  on which the New  York Stock Exchange is  normally open ("business day") if
the distribution date is  not a business day,  automatically be received by  the
transfer agent for each of the Accumulation Funds, on behalf of such participant
and  applied  on that  date to  purchase  shares (or  fractions thereof)  of the
Accumulation Fund chosen at net asset value as computed as of 4:00 p.m.  eastern
time on each such date. All distributions will be reinvested in the Accumulation
Fund  chosen and no part  thereof will be retained  in a separate account. These
purchases will be made without a sales charge.
 
    The Transfer Agent of the Accumulation Fund will mail to each participant in
the  Accumulation  Plan  a  quarterly  statement  containing  a  record  of  all
transactions  involving  purchases  of Accumulation  Fund  shares  (or fractions
thereof) with Trust  interest distributions or  as a result  of reinvestment  of
Accumulation  Fund  dividends. Any  distribution of  principal used  to purchase
shares of an  Accumulation Fund  will be  separately confirmed  by the  Transfer
Agent.  Unitholders will also  receive distribution statements  from the Trustee
detailing the amounts transferred to their Accumulation Fund accounts.
 
    Participants may at any time, by so notifying the Trustee in writing,  elect
to  change  the  Accumulation  Fund into  which  their  distributions  are being
reinvested, to change from principal  only reinvestment to reinvestment of  both
 
                                       9
<PAGE>
principal and interest or vice versa, or to terminate their participation in the
Accumulation  Plan altogether and receive future distributions on their Units in
cash. There will be no  charge or other penalty for  such change of election  or
termination.  The character of Trust distributions  for income tax purposes will
remain unchanged even if they are reinvested in an Accumulation Fund.
 
INFORMATION ABOUT THE SPONSOR
 
Since our founding  in 1898, Nuveen  has been synonymous  with investments  that
withstand  the  test of  time.  Today, we  offer  a broad  range  of investments
designed for mature investors whose portfolio  is the principal source of  their
ongoing  financial  security. More  than  1.3 million  investors  have entrusted
Nuveen to help them maintain the lifestyle they currently enjoy.
 
    A value investing  approach--purchasing securities of  strong companies  and
communities  that represent good long-term value--is the cornerstone of Nuveen's
investment philosophy.  It is  a  careful, long-term  strategy that  offers  the
potential for attractive returns with moderated risk. Successful value investing
begins  with in-depth research and a discerning eye for marketplace opportunity.
Nuveen's team of investment professionals is backed by the discipline, resources
and expertise of almost a century of investment experience, including one of the
most recognized research departments in the industry.
 
    To meet  the unique  circumstances and  financial planning  needs of  mature
investors,  Nuveen  offers  a  wide array  of  taxable  and  tax-free investment
products--including  equity  and   fixed-income  mutual   funds,  unit   trusts,
exchange-traded  funds, customized asset management services and cash management
products. Nuveen is a subsidiary of The  John Nuveen Company which, in turn,  is
approximately  78% owned by the St. Paul  Companies, Inc. ("ST. PAUL"). St. Paul
is located  in St.  Paul,  Minnesota and  is  principally engaged  in  providing
property-liability  insurance through  subsidiaries. Nuveen  is a  member of the
National Association of  Securities Dealers,  Inc. and  the Securities  Industry
Association  and has  its principal office  located in Chicago  (333 West Wacker
Drive). Nuveen maintains 11 regional offices.
 
    To help advisers and investors better understand and more efficiently use an
investment in  the Trusts  to  reach their  investment  goals, the  Sponsor  may
advertise and create specific investment programs and systems. For example, such
activities may include presenting information on how to use an investment in the
Trusts, alone or in combination with an investment in other mutual funds or unit
investment trusts sponsored by Nuveen, to accumulate assets for future education
needs  or periodic payments such as  insurance premiums. The Sponsor may produce
software or additional sales literature to  promote the advantages of using  the
Trusts to meet these and other specific investor needs.
 
                                       10
<PAGE>
DESCRIPTION OF RATINGS*
 
    STANDARD  & POOR'S CORPORATION.  A  description of the applicable Standard &
Poor's Corporation rating symbols and their meanings follows:
 
    A Standard & Poor's rating is  a current assessment of the  creditworthiness
of  an obligor with respect  to a specific debt  obligation. This assessment may
take into consideration obligors such as guarantors, insurers or lessees.
 
    The rating is  not a recommendation  to purchase, sell  or hold a  security,
inasmuch  as  it  does not  comment  as to  market  price or  suitability  for a
particular investor.
 
    The ratings are  based on  current information  furnished by  the issuer  or
obtained by Standard & Poor's from other sources it considers reliable. Standard
&  Poor's does not  perform an audit in  connection with any  rating and may, on
occasion, rely on unaudited financial  information. The ratings may be  changed,
suspended  or withdrawn as  a result of  changes in, or  unavailability of, such
information, or for other circumstances.
 
    The ratings are based, in varying degrees, on the following considerations:
 
     I.  Likelihood of default--capacity  and willingness of  the obligor as  to
         the timely payment of interest and repayment of principal in accordance
         with the terms of the obligation;
 
     II.  Nature of and provisions of the obligation;
 
    III.  Protection  afforded by, and  relative position of,  the obligation in
          the event of  bankruptcy, reorganization or  other arrangements  under
          the laws of bankruptcy and other laws affecting creditors' rights.
 
    AAA--This  is the  highest rating  assigned by Standard  & Poor's  to a debt
obligation. Capacity to pay interest and repay principal is extremely strong.
 
    AA--Bonds rated AA  have a very  strong capacity to  pay interest and  repay
principal, and differ from the highest rated issues only in small degree.
 
    A--Bonds rated A have a strong capacity to pay interest and repay principal,
although they are somewhat more susceptible to the adverse effects of changes in
circumstances and economic conditions than bonds in higher rated categories.
 
    BBB--Bonds  rated BBB  are regarded  as having  an adequate  capacity to pay
interest and repay principal. Whereas they normally exhibit adequate  protection
parameters,  adverse  economic  conditions or  changing  circumstances  are more
likely to lead to a  weakened capacity to pay  interest and repay principal  for
bonds in this category than for bonds in the higher rated categories.
 
    PLUS  (+) OR MINUS (-): The ratings from "AA" to "BB" may be modified by the
addition of a  plus or minus  sign to  show relative standing  within the  major
rating categories.
 
    PROVISIONAL   RATINGS:  The  letter   "p"  indicates  that   the  rating  is
provisional. A  provisional  rating assumes  the  successful completion  of  the
project  being financed by the  issuance of the bonds  being rated and indicates
that payment of debt service requirements is largely or entirely dependent  upon
the successful and timely completion of the project. This rating, however, while
addressing  credit quality  subsequent to  completion of  the project,  makes no
comment on the  likelihood of,  or the  risk of  default upon  failure of,  such
completion.  Accordingly,  the investor  should exercise  his own  judgment with
respect to such likelihood and risk.
 
    NOTE RATINGS:  A  Standard  &  Poor's note  rating  reflects  the  liquidity
concerns  and market access risks unique to notes.  Notes due in 3 years or less
will likely  receive a  note rating.  Notes maturing  beyond 3  years will  most
likely receive a long-term debt rating.
 
    Note rating symbols are as follows:
 
        SP-1  Very  strong  or strong  capacity to  pay principal  and interest.
              Those   issues   determined   to   possess   overwhelming   safety
              characteristics will be given a plus (+) designation.
 
        SP-2  Satisfactory capacity to pay principal and interest.
 
    MOODY'S  INVESTORS  SERVICE, INC.   A  brief  description of  the applicable
Moody's Investors Service, Inc. rating symbols and their meanings follows:
 
    Aaa--Bonds which are rated Aaa are judged to be the best quality. They carry
the smallest degree of  investment risk and are  generally referred to as  "gilt
edge."  Interest payments are protected by a large or by an exceptionally stable
margin and principal is secure. While the various protective elements are likely
to change, such changes  as can be  visualized are most  unlikely to impair  the
fundamentally  strong position of such issues. Their safety is so absolute that,
 
- ----------
*As published by the rating companies.
 
                                       11
<PAGE>
with the  occasional  exception  of  oversupply in  a  few  specific  instances,
characteristically,  their  market  value  is affected  solely  by  money market
fluctuations.
 
    Aa--Bonds which  are rated  Aa  are judged  to be  of  high quality  by  all
standards. Together with the Aaa group they comprise what are generally known as
high  grade bonds. They are  rated lower than the  best bonds because margins of
protection may  not  be  as  large  as in  Aaa  securities  or  fluctuations  of
protective  elements may be of greater amplitude  or there may be other elements
present which  make the  long-term  risks appear  somewhat  larger than  in  Aaa
securities.  Their  market value  is virtually  immune to  all but  money market
influences, with  the  occasional exception  of  oversupply in  a  few  specific
instances.
 
    A--Bonds  which are rated A possess many favorable investment attributes and
are to be considered as upper medium grade obligations. Factors giving  security
to  principal and interest are considered  adequate, but elements may be present
which suggest a susceptibility to impairment sometime in the future. The  market
value  of A-rated bonds may be influenced to some degree by economic performance
during a sustained period of depressed business conditions, but, during  periods
of  normalcy,  A-rated  bonds  frequently  move  in  parallel  with  Aaa  and Aa
obligations, with  the occasional  exception  of oversupply  in a  few  specific
instances.
 
    Moody's  bond rating  symbols may contain  numerical modifiers  of a generic
rating classification. The modifier 1 indicates that the bond ranks at the  high
end  of its  category; the  modifier 2  indicates a  mid-range ranking;  and the
modifier 3 indicates that the issue ranks in the lower end of its generic rating
category.
 
    Baa--Bonds which are rated Baa  are considered as medium grade  obligations,
i.e.,  they are neither  highly protected nor  poorly secured. Interest payments
and principal security appear  adequate for the  present but certain  protective
elements  may be lacking or may  be characteristically unreliable over any great
length of time. Such  bonds lack outstanding  investment characteristics and  in
fact  have speculative  characteristics as well.  The market  value of Baa-rated
bonds is more  sensitive to changes  in economic circumstances,  and aside  from
occasional  speculative factors applying to some bonds of this class, Baa market
valuations move in  parallel with Aaa,  Aa and A  obligations during periods  of
economic normalcy, except in instances of oversupply.
 
    Con.  (--)--Bonds for which the security depends upon the completion of some
act or the  fulfillment of  some condition  are rated  conditionally. These  are
bonds  secured by (a)  earnings of projects under  construction, (b) earnings of
projects unseasoned  in  operation  experience, (c)  rentals  which  begin  when
facilities are completed, or (d) payments to which some other limiting condition
attaches.  Parenthetical rating denotes probable  credit stature upon completion
of construction or elimination of basis of condition.
 
NOTE RATINGS:
 
    MIG 1  This designation  denotes  best  quality.  There  is  present  strong
           protection  by established cash flows,  superior liquidity support or
           demonstrated broad-based access to the market for refinancing.
 
    MIG 2  This designation  denotes high  quality.  Margins of  protection  are
           ample although not so large as in the preceding group.
 
    FITCH   IBCA,  INC.  (formerly  Fitch   Investors  Service,  L.P.)  A  brief
description of the applicable Fitch IBCA, Inc. rating symbols and their meanings
follow:
 
    AAA--Bonds considered  to be  investment  grade and  of the  highest  credit
quality.  The obligor  has an exceptionally  strong ability to  pay interest and
repay principal,  which is  unlikely to  be affected  by reasonably  foreseeable
events.
 
    AA--Bonds considered to be investment grade and of very high credit quality.
The  obligor's  ability to  pay  interest and  repay  principal is  very strong,
although not quite as strong as bonds rated  AAA. Bonds rated in the AAA and  AA
categories are not significantly vulnerable to foreseeable future developments.
 
    A--Bonds  considered to be investment grade  and of high credit quality. The
obligor's ability  to pay  interest  and repay  principal  is considered  to  be
strong, but may be more vulnerable to adverse changes in economic conditions and
circumstances than bonds with higher ratings.
 
    BBB--Bonds  considered  to be  investment grade  and of  satisfactory credit
quality. The obligor's ability to pay interest and repay principal is considered
to be  adequate.  Adverse  changes in  economic  conditions  and  circumstances,
however,  are more likely to  have adverse impact on  these bonds, and therefore
impair timely payment. The likelihood that the ratings of these bonds will  fall
below investment grade is higher than for bonds with higher ratings.
 
    To  provide more detailed indications  of credit quality, the  AA, A and BBB
ratings may be modified by the addition of a plus or minus sign to show relative
standing within these major rating categories.
 
NOTE RATINGS:
 
    FIN-1  Notes assigned  this  rating are  regarded  as having  the  strongest
           degree of assurance for timely payment.
 
                                       12
<PAGE>
    FIN-2  Notes  assigned this rating reflect a  degree of assurance for timely
           payment only slightly less in degree than the highest category.
 
HOW THE TRUST COMPARES PERFORMANCE
 
    The Sponsor may compare the estimated returns of the Trust with the  returns
or  yields  of  other  tax-free  and taxable  investments,  often  on  a taxable
equivalent basis. In addition, the Sponsor  from time to time may quote  various
performance  measures and  studies in  order to  compare the  historical returns
available from an investment  in municipal securities  with investments in  both
tax-free and taxable securities.
 
    Nuveen  Research prepared one such study  which compared the after-tax value
of $100,000  initially  invested in  1977  in various  asset  classes  including
municipal  bonds, treasury bonds and corporate  bonds. As indicated in the chart
provided below,  the  20-year study  shows  that municipal  bonds  significantly
outperformed  corporate  and  treasury  bonds once  the  effects  of  taxes were
factored in. In fact, over the 20-year period, municipal bond returns in dollars
were almost double those of treasury bonds.
 
                 AFTER-TAX VALUE OF $100,000 INVESTED IN 1977*
 
   
    The graph  appearing on  this page  of the  Information Supplement  compares
after-tax  total returns  of $100,000  initially in 1977  in each  of the Lehman
Brothers MuniBond Index, Long-Term Treasury Index and Long-Term Corporate Index.
As indicated in the  graph, such an investment  in the Lehman Brothers  MuniBond
Index,  Long-Term  Treasury  Index  and  Long-Term  Corporate  Index  would have
appreciated to  $511,039, $274,434,  and $298,682,  respectively at  the end  of
1996.  The  graph  assumes all  proceeds  of  investment are  reinvested  at the
respective index rates at the time of reinvestment and also assumes that 20%  of
the assets in each category are turned over annually and proceeds are reinvested
in the respective indexes. The tax rates assumed to generate the after-tax total
returns  were based upon the income and  capital gain rates applicable each year
from 1977-1996 for an investor who earned the inflation-adjusted equivalents  of
$500,000  in 1996. In addition, treasury returns were "grossed up" an assumed 5%
to take into account the Treasuries' exemption from state income tax. The  graph
is  for  illustrative  purposes  only,  and does  not  represent  the  return or
performance of any  Nuveen Tax-Free Unit  Trust and is  not intended to  predict
future results.
    
 
    *  The  graph compares  after-tax total  returns  using the  Lehman Brothers
MuniBond Index,  Long-Term Treasury  Index and  Long-Term Corporate  Index.  The
graph  assumes all proceeds of investment are reinvested at the respective index
rates at the time  of reinvestment and  also assumes that 20%  of the assets  in
each  category  are turned  over  annually and  proceeds  are reinvested  in the
respective indexes.  The  tax rates  assumed  to generate  the  after-tax  total
returns  were based upon the income and  capital gain rates applicable each year
from 1977-1996 for an investor who earned the inflation-adjusted equivalents  of
$100,000  in 1996. In addition, treasury returns were "grossed up" an assumed 5%
to take into account the Treasuries' exemption from state income tax. The  graph
is  for  illustrative  purposes  only,  and does  not  represent  the  return or
performance of any  Nuveen Tax-Free Unit  Trust and is  not intended to  predict
future results.
 
    A  comparison  of  the  estimated  returns of  the  Trust  and  the historic
performance  of  municipal  bonds  to  the  returns  and  performance  of  other
investments  is  one  element  to  consider  in  making  an  informed investment
decision. Taxable investments have  investment characteristics that differ  from
those  of the Trust.  U.S. Government bonds are  long-term investments backed by
the full faith  and credit of  the U.S.  Government and are  subject to  federal
income  tax  but are  exempt from  state  income taxes.  Bank CDs  are generally
short-term FDIC insured investments, which pay fixed principal and interest  but
are subject to fluctuating rollover rates. Both bank CDs and corporate bonds are
generally subject to both federal and state income taxes. Money market funds are
short  term investments  with stable  net asset  values, fluctuating  yields and
special features that enhance liquidity.
 
                                       13
<PAGE>
HOW TO CALCULATE YOUR ESTIMATED INCOME
 
    The examples provided below illustrate how to calculate the estimated annual
income generated by a hypothetical $10,000 investment in each respective  Trust.
The  illustrations assume that the  investment was made on  the day prior to the
date of deposit by an investor  electing the monthly distribution plan and  that
the  portfolio contains  all the  securities described  in the  portfolio. These
hypothetical examples are  for illustrative  purposes only and  not intended  to
reflect  or predict the results of any  actual investment and do not contemplate
changes to the portfolio or expenses.
 
<TABLE>
<S>                           <C>        <C>                           <C>        <C>
EXAMPLE OF HOW TO CALCULATE YOUR ESTIMATED INCOME:
 
    MASSACHUSETTS INSURED TRUST 152
 
    $10,000                    DIVIDED  BY $100.39                     =          99.611
    Investment                           Offering price and                       # of units purchased
    (as of 03/24/98)                     accrued interest
 
    99.611                    X          $4.6063                       =          $458.84
    # of units purchased                 Annual income per unit                   annual income
                                         (monthly plan)
</TABLE>
 
<TABLE>
<S>                           <C>        <C>                           <C>        <C>
EXAMPLE OF HOW TO CALCULATE YOUR ESTIMATED INCOME:
 
    NEW YORK INSURED TRUST 278
 
    $10,000                    DIVIDED  BY $102.27                     =          97.780
    Investment                           Offering price and                       # of units purchased
    (as of 03/24/98)                     accrued interest
 
    97.780                    X          $4.6824                       =          $457.85
    # of units purchased                 Annual income per unit                   annual income
                                         (monthly plan)
</TABLE>
 
<TABLE>
<S>                           <C>        <C>                           <C>        <C>
EXAMPLE OF HOW TO CALCULATE YOUR ESTIMATED INCOME:
 
    PENNSYLVANIA INSURED TRUST 234
 
    $10,000                    DIVIDED  BY $100.14                     =          99.860
    Investment                           Offering price and                       # of units purchased
    (as of 03/24/98)                     accrued interest
 
    99.860                    X          $4.6035                       =          $459.71
    # of units purchased                 Annual income per unit                   annual income
                                         (monthly plan)
</TABLE>
 
                                       14
<PAGE>
                                   APPENDIX A
                            MASSACHUSETTS DISCLOSURE
 
ECONOMIC FACTORS--MASSACHUSETTS
 
    Except   to  the  extent  the   Massachusetts  Trust  invests  in  temporary
investments, the Massachusetts Trust  will invest substantially  all of its  net
assets  in  Massachusetts  Municipal  Obligations.  The  Massachusetts  Trust is
therefore susceptible  to political,  economic or  regulatory factors  affecting
issuers   of  Massachusetts  Municipal  Obligations.  Without  intending  to  be
complete, the following briefly summarizes  the current financial situation,  as
well  as some of the  complex factors affecting the  financial situation, in the
Commonwealth of Massachusetts (the "COMMONWEALTH").  It is derived from  sources
that  are generally available to  investors and is based  in part on information
obtained from various agencies in Massachusetts. No independent verification has
been made of the accuracy or completeness of the following information.
 
    There can  be no  assurance that  current or  future statewide  or  regional
economic  difficulties,  and  the  resulting  impact  on  Commonwealth  or local
governmental finances generally, will not  adversely affect the market value  of
Massachusetts  Obligations in the Trust or the ability of particular obligors to
make timely payments of debt service on (or relating to) those obligations.
 
    Since 1988,  there has  been a  significant slowdown  in the  Commonwealth's
economy,  as indicated by  a rise in  unemployment, a slowing  of its per capita
income  growth   and  declining   state  revenues.   Since  fiscal   1991,   the
Commonwealth's   revenues   for   state   government   programs   have  exceeded
expenditures; however, no assurance  can be given that  lower than expected  tax
revenues will not resume and continue.
 
    1996  FISCAL  YEAR  BUDGET.   On  July  21, 1995,  the  Governor  signed the
Commonwealth's budget  for fiscal  1996.  The fiscal  1996  budget is  based  on
estimated  budgeted revenues and other sources of approximately $16.778 billion,
which includes fiscal  1996 tax  revenues of $11.653  billion. Estimated  fiscal
1996  tax revenues are approximately $490 million, or 4.3% higher than estimated
fiscal 1995 tax revenues.
 
    Fiscal  1996  non-tax  revenues  are  projected  to  total  $5.158  billion,
approximately  $66 million,  or 1.3% less  than fiscal 1995  non-tax revenues of
approximately $5.224 billion. Federal  reimbursements are projected to  decrease
by  approximately $1 million from approximately $2.970 billion in fiscal 1995 to
approximately $2.969 billion in fiscal 1996, primarily as a result of  increased
reimbursements  for Medicare spending,  offset by a  reduction in reimbursements
received in 1995  for one-time  Medicare expenses  incurred in  fiscal 1994  and
fiscal  1995.  Fiscal 1996  departmental revenues  are  projected to  decline by
approximately $94 million, or 7.4%, from approximately $1.273 billion in  fiscal
1995  to approximately $1.179 billion in fiscal 1996. Major changes in projected
non-tax received for fiscal 1996 include a decline in motor vehicle license  and
registration  fees, reduction of abandoned property  revenues and a decrease due
to non-recurring revenues  received in  fiscal 1995 from  hospitals and  nursing
homes  as part of  Medicare fiscal rate settlements  and other reimbursements by
municipal hospitals to the state.
 
    Fiscal  1996  appropriations   in  the  Annual   Appropriations  Act   total
approximately   $16.847   billion,  including   approximately  $25   million  in
gubernatorial vetoes overridden  by the legislature.  In the final  supplemental
budget  for fiscal 1995, approved  on August 24, 1995,  another $71.1 million of
appropriations were continued for use in 1996.
 
    As of  February  1, 1996,  the  Governor had  signed  into law  fiscal  1996
supplemental  appropriations  totalling approximately  $23.5  million, including
approximately $12.6  million  to  fund higher  education  collective  bargaining
contracts  and  $5.6  million  for  the  Department  of  Social  Services. These
appropriations  were  offset  by  approximately  $10.4  million  in  line   item
reductions,  including a reduction of $9.8  million for the state's debt service
contract assistance  to  the  MBTA.  Both  the  House  and  Senate  have  passed
supplemental  appropriation bills totalling $64.8  million primarily relating to
snow and ice  removal costs  incurred by both  the Commonwealth  and cities  and
towns.  The bills are currently awaiting resolution by a conference committee of
the House and Senate.  On January 26,  1996 and February  9, 1996, the  Governor
filed  additional supplemental appropriation  bills totalling approximately $7.3
million  for  costs  relating   to  prison  overcrowding   relief  as  well   as
reimbursement costs associated with a court settlement. No action has been taken
on these bills by either branch of the Legislature.
 
    As  of May 28, 1996, fiscal 1996 projected spending is approximately $16.963
billion, including  approximately  $153.2 million  reserved  for  contingencies.
Projected  revenues  are  approximately  $16.851 billion.  The  fiscal  1996 tax
revenue  projection  is  $11.684  billion,  which  represents  an  increase   of
approximately  $80 million  from the  earlier estimate,  based upon  tax revenue
collections through April 1996.
 
    The fiscal 1996 budget is based  on numerous spending and revenue  estimates
the achievement of which cannot be assured.
 
    1995  FISCAL YEAR.   Budgeted revenues and  other sources, including non-tax
revenues,  collected  in  fiscal   1995  were  approximately  $16.387   billion,
approximately  $837  million,  or 5.4%  above  fiscal 1994  revenues  of $15.550
billion.  Fiscal  1995  tax  revenues  collections  were  approximately  $11.163
billion, approximately $12 million above the Department of
 
                                      A-1
<PAGE>
Revenue's  revised fiscal year 1995 tax  revenue estimate of $10.151 billion and
$556 million, or 5.2% above fiscal year tax revenues of $10.607 billion.
 
    Budgeted  expenditures  and  other  uses  of  funds  in  fiscal  1995   were
approximately  $16.251 billion, approximately $728 million, or 4.7% above fiscal
1994 budgeted expenditures and uses of $15.523 billion.
 
    The Commonwealth ended fiscal  1995 with an operating  gain of $137  million
and an ending fund balance of $726 million.
 
    On  February 10, 1995, the  Governor signed into law  certain reforms to the
Commonwealth's program  for Aid  to Families  with Dependent  Children  ("AFDC")
which  will take effect on July 1,  1995, subject to federal approval of certain
waivers. The revised program reduces AFDC benefits to able bodied recipients  by
2.75%,  while allowing  them to  keep a  larger portion  of their  earned wages,
requires approximately  22,000 able-bodied  parents of  school-aged children  to
work   or  perform  community  service  for  20  hours  per  week  and  requires
approximately 16,000 recipients who  have children between the  ages of two  and
six  to participate  in an  education or  training program  or perform community
service. The plan also establishes a pilot program for up to 2,000  participants
that  offers  tax  credits and  wage  subsidies  to employers  who  hire welfare
recipients. Parents who find employment  will be provided with extended  medical
benefits  and day care benefits  for up to one  year. The plan mandates paternal
identification, expands funding for anti-fraud initiatives, and requires parents
on AFDC  to immunize  their children.  Parents who  are disabled,  caring for  a
disabled  child, have a child under the age  of two, or are teen-agers living at
home and attending high school, will continue to receive cash assistance.  Since
most  provisions of  the new  law do  not take  effect until  July 1,  1995, the
Executive  Office  for  Administration  projects  that  the  reforms  will   not
materially  affect  fiscal  1995  public assistance  spending.  The  fiscal 1995
expenditure estimate of $16.449 billion includes $247.8 million appropriated  to
fund  the Commonwealth's public assistance programs  for the last four months of
fiscal 1995. The Commonwealth  is currently evaluating the  new law's impact  on
fiscal 1996 projected spending for public assistance programs.
 
    On  November 8, 1994, the voters  in the statewide general election approved
an initiative petition that would slightly increase the portion of the  gasoline
tax  revenue credited to the Highway Fund, one of the Commonwealth's three major
budgetary funds, prohibit the transfer of  money from the Highway Fund to  other
funds for non-highway purposes and not permit including the Highway Fund balance
in  the computation  "consolidated net  surplus" for  purposes of  state finance
laws. The initiative petition  also provides that no  more than 15% of  gasoline
tax  revenues may be used for mass transportation purposes, such as expenditures
related to  the Massachusetts  Bay Transit  Authority. The  Executive Office  of
Administration  and Finance  is analyzing  the effect,  if any,  this initiative
petition, which became  law on December  8, 1994,  may have on  the fiscal  1995
budget  and  it currently  does not  expect  it to  have any  materially adverse
impact. This is not  a constitutional amendment and  is subject to amendment  or
repeal  by the  Legislature, which  may also,  notwithstanding the  terms of the
petition, appropriate moneys from the Highway Fund in such amounts and for  such
purposes  as it  determines, subject only  to a  constitutional restriction that
such moneys be used for highways or mass transit purposes.
 
    1994 FISCAL YEAR.   Fiscal 1994 tax  revenue collections were  approximately
$10.607  billion, $87 million below the Department of Revenue's fiscal year 1994
tax revenue estimate of $10.694 billion  and $677 million above fiscal 1993  tax
revenues  of  $9.930 billion.  Budgeted  revenues and  other  sources, including
non-tax revenues, collected in fiscal  1994 were approximately $15.550  billion.
Total  revenues and  other sources increased  by approximately  5.7% from fiscal
1993 to fiscal 1994 while  tax revenues increased by  6.8% for the same  period.
Budgeted  expenditures and other uses of funds in fiscal 1994 were approximately
$15.523 billion,  which is  $826.5  million or  approximately 5.6%  higher  than
fiscal 1993 budgeted expenditures and other uses.
 
    As  of June 30,  1994, the Commonwealth  showed a year-end  cash position of
approximately $757 million, as compared to a projected position of $599 million.
 
    In June, 1993,  the Legislature  adopted and  the Governor  signed into  law
comprehensive   education  reform  legislation.  This  legislation  required  an
increase in expenditures for education purposes above fiscal 1993 base  spending
of  $1.288 billion of  approximately $175 million in  fiscal 1994. The Executive
Office  for  Administration  and  Finance   expects  the  annual  increases   in
expenditures  above  the  fiscal 1993  base  spending  of $1.288  billion  to be
approximately $396 million in fiscal 1995, $625 million in fiscal 1996 and  $868
million  in fiscal 1997. Additional annual  increases are also expected in later
fiscal years. The  fiscal 1995 budget  as signed by  the Governor includes  $896
million in appropriations to satisfy this legislation.
 
    1993  FISCAL YEAR.  The Commonwealth's  budgeted expenditures and other uses
were approximately $14.696 billion in fiscal 1993, which is approximately $1.280
billion or  9.6% higher  than fiscal  1992 expenditures  and other  uses.  Final
fiscal  1993 budgeted expenditures were $23  million lower than the initial July
1992 estimates of fiscal 1993 budgeted expenditures. Budgeted revenues and other
sources for fiscal  1993 totalled approximately  $14.710 billion, including  tax
revenues  of  $9.930  billion. Total  revenues  and other  sources  increased by
approximately 6.9% from fiscal 1992 to fiscal 1993, while tax revenues increased
by 4.7%  for the  same period.  Overall, fiscal  1993 ended  with a  surplus  of
revenues and
 
                                      A-2
<PAGE>
other  sources over expenditures  and other uses of  $13.1 million and aggregate
ending fund balances  in the  budgeted operating  funds of  the Commonwealth  of
approximately $562.5 million. After payment in full of the distribution of local
aid  to the Commonwealth's cities and towns  ("Local Aid") and the retirement of
short  term  debt,  the  Commonwealth  showed  a  year  end  cash  position   of
approximately  $622.2 million,  as compared  to a  projected position  of $485.1
million.
 
    1992 FISCAL YEAR.  The  Commonwealth's budgeted expenditures and other  uses
were approximately $13.4 billion in fiscal 1992, which is $238.7 million or 1.7%
lower  than  fiscal  1991  budgeted  expenditures.  Final  fiscal  1992 budgeted
expenditures were $300  million more  than the  initial July  1991 estimates  of
budgetary  expenditures,  due in  part to  increases  in certain  human services
programs, including an increase of $268.7  million for the Medicaid program  and
$50.0  million  for  mental retardation  consent  decree  requirements. Budgeted
revenues and other sources for fiscal 1992 totalled approximately $13.7  billion
(including  tax revenues of approximately  $9.5 billion), reflecting an increase
of approximately 0.7% from fiscal  1991 to 1992 and an  increase of 5.4% in  tax
revenues  for the same period.  Overall, fiscal 1992 is  estimated to have ended
with an excess of revenues and other sources over expenditures and other uses of
$312.3 million. After  payment in  full of  Local Aid  in the  amount of  $514.0
million  due  on June  30, 1992,  retirement  of the  Commonwealth's outstanding
commercial paper  (except for  approximately $50  million of  bond  anticipation
notes)  and certain other short term borrowings, as of June 30, 1992, the end of
fiscal 1992, the Commonwealth showed  a year-end cash position of  approximately
$731 million, as compared with the Commonwealth's cash balance of $182.3 million
at the end of fiscal 1991.
 
    1991  FISCAL YEAR.  Budgeted expenditures for fiscal 1991 were approximately
$13.659 billion, as against budgeted revenues and other sources of approximately
$13.634 billion. The  Commonwealth suffered an  operating loss of  approximately
$21.2  million. Application of the adjusted  fiscal 1990 fund balances of $258.3
million resulted in a fiscal 1991 budgetary surplus of $237.1 million. State law
requires that approximately $59.2 million of the fiscal year ending balances  of
$237.1  million be placed in the Stabilization  Fund, a reserve from which funds
can be appropriated (i) to make up any difference between actual state  revenues
in  any fiscal year  in which actual  revenues fall below  the allowable amount,
(ii) to replace state and local losses by federal funds or (iii) for any  event,
as  determined by the legislature, which threatens the health, safety or welfare
of the  people  or the  fiscal  stability of  the  Commonwealth or  any  of  its
political subdivisions.
 
    Upon  taking office in January  1991, the new Governor  proposed a series of
legislative and  administrative  actions, including  withholding  of  allotments
under  Section 9C of Chapter  29 of the General  Laws, intended to eliminate the
projected deficits.  The  new Governor's  review  of the  Commonwealth's  budget
indicated  projected spending of  approximately $14.1 billion  with an estimated
$850 million in  budget balancing  measures that would  be needed  prior to  the
close  of fiscal  1991. At  that time,  estimated tax  revenues were  revised to
approximately $8.8 billion, $903 million less than was estimated at the time the
fiscal 1991  budget  was  adopted.  The Legislature  adopted  a  number  of  the
Governor's  recommendations and the Governor took certain administrative actions
not requiring legislative approval, including  the adoption of a state  employee
furlough  program. It is estimated by  the Commonwealth that spending reductions
achieved  through  savings  initiatives  and  withholding  of  allotments  total
approximately  $484.3  million  in  aggregate for  fiscal  1991.  However, these
savings and reductions may be impacted negatively by litigation pursued by third
parties concerning the Governor's actions under Section 9C of Chapter 29 of  the
General Laws and with regard to the state employee furlough program.
 
    In  addition, the new administration  in May 1991 filed  an amendment to its
Medicaid state  plan that  enables  it to  claim  50% federal  reimbursement  on
uncompensated  care payments  for certain  hospitals in  the Commonwealth.  As a
result, in fiscal 1991, the Commonwealth obtained additional non-tax revenues in
the form  of  federal reimbursements  equal  to approximately  $513  million  on
account  of uncompensated care payments. This reimbursement claim was based upon
recent amendments of federal law contained in the Omnibus Budget  Reconciliation
Act   of  1990  and,  consequently,  on  relatively  undeveloped  federal  laws,
regulations and guidelines. At the request of the federal Health Care  Financing
Administration,  the Office of Inspector General of the United States Department
of Health and Human  Services has commenced an  audit of the reimbursement.  The
administration,  which had  reviewed the matter  with the  Health Care Financing
Administration  prior  to   claiming  the  reimbursement,   believes  that   the
Commonwealth  will prevail in  the audit. If the  Commonwealth does not prevail,
the Commonwealth  would  have the  right  to contest  an  appeal, but  could  be
required to pay all or part of Medicaid reimbursements with interest and to have
such amount deducted from future reimbursement payments.
 
    EMPLOYMENT.   Reversing  a trend of  relatively low  unemployment during the
early and  mid 1980's,  the Massachusetts  unemployment rate  beginning in  1990
increased  significantly to where the  Commonwealth's unemployment rate exceeded
the national unemployment rate. During 1990, the Massachusetts unemployment rate
increased from 4.5% in January to 6.1%  in July to 6.7% in August. During  1991,
the  Massachusetts  unemployment rate  averaged  9.0% while  the  average United
States unemployment rate  was 6.7%. The  Massachusetts unemployment rate  during
1992  averaged 8.5% while the average  United States unemployment rate was 7.4%.
Since 1993, the average monthly unemployment rate has
 
                                      A-3
<PAGE>
declined steadily.  The Massachusetts  unemployment rate  in February  1996  was
5.0%,  as compared with the United States unemployment rate of 5.5% for the same
period.  Other  factors  which  may  significantly  and  adversely  affect   the
employment  rate in  the Commonwealth  include reductions  in federal government
spending on defense-related  industries. Due to  this and other  considerations,
there  can  be  no assurance  that  unemployment  in the  Commonwealth  will not
increase in the future.
 
    DEBT RATINGS.   S&P  currently rates  the Commonwealth's  uninsured  general
obligation  bonds at A+. At the same  time, S&P currently rates state and agency
notes at SP1. From 1989 through 1992, the Commonwealth had experienced a  steady
decline  in its  S&P rating, with  its decline  beginning in May  1989, when S&P
lowered its  rating on  the Commonwealth's  general obligation  bonds and  other
Commonwealth  obligations  from AA+  to AA  and continuing  a series  of further
reductions until March 1992, when the rating was affirmed at BBB.
 
    Moody's currently  rates  the Commonwealth's  uninsured  general  obligation
bonds  at A1. From 1989 through 1992,  the Commonwealth had experienced a steady
decline in its rating by  Moody's since May 1989.  In May 1989, Moody's  lowered
its  rating on the Commonwealth's  notes from MIG-1 to  MIG-2, and its rating on
the Commonwealth's commercial paper from P-1  to P-2. On June 21, 1989,  Moody's
reduced  the Commonwealth's general obligation rating  from Aa to A. On November
15, 1989, Moody's reduced the  rating on the Commonwealth's general  obligations
from  A  to Baa1,  and  on March  9,  1990, Moody's  reduced  the rating  of the
Commonwealth's general obligation bonds from Baa1 to Baa.
 
    There can be no assurance that these ratings will continue.
 
    In recent  years, the  Commonwealth and  certain of  its public  bodies  and
municipalities have faced serious financial difficulties which have affected the
credit  standing  and borrowing  abilities of  Massachusetts and  its respective
entities and may have contributed to higher interest rates on debt  obligations.
The continuation of, or an increase in, such financial difficulties could result
in  declines  in  the market  values  of,  or default  on,  existing obligations
including Massachusetts Obligations  in the  Trust. Should there  be during  the
term  of  the Trust  a financial  crisis relating  to Massachusetts,  its public
bodies or municipalities, the market value and marketability of all  outstanding
bonds  issued by the  Commonwealth and its  public authorities or municipalities
including the Massachusetts Obligations in the Trust and interest income to  the
Trust could be adversely affected.
 
    TOTAL  BOND  AND  NOTE  LIABILITIES.    The  total  general  obligation bond
indebtedness of  the  Commonwealth  (including Dedicated  Income  Tax  Debt  and
Special  Obligation Debt) as of April 1, 1996 was approximately $10.093 billion.
There were also  outstanding approximately  $240 million  in general  obligation
notes  and other  short term  general obligation debt.  The total  bond and note
liabilities of the Commonwealth as of  April 1, 1996, including guaranteed  bond
and contingent liabilities, was approximately $13.818 billion.
 
    DEBT  SERVICE.    During  the  1980s,  capital  expenditures  were increased
substantially, which  has had  a short  term impact  on the  cash needs  of  the
Commonwealth  and also  accounts for a  significant rise in  debt service during
that period.  In November,  1988, the  Executive Office  for Administration  and
Finance  established an administrative limit  on state-financed capital spending
in  the  Capital  Projects  Fund  of  $925  million  per  fiscal  year.  Capital
expenditures were $847.0 million, $694.1 million, $575.9 million, $760.6 million
and  $902.2 million in  fiscal 1991, fiscal  1992, fiscal 1993,  fiscal 1994 and
fiscal  1995,  respectively.  Commonwealth-financed  capital  expenditures   are
projected  to  be  approximately $898.0  million  in fiscal  1996.  Debt service
expenditures for fiscal 1991, fiscal 1992,  fiscal 1993, fiscal 1994 and  fiscal
1995  were $942.3 million,  $898.3 million, $1.140  billion, $1.149 billion, and
$1.231 billion,  respectively,  and are  projected  to be  approximately  $1.199
billion  for fiscal 1996. The amounts represented do not include debt service on
notes issued  to  finance  certain Medicare-related  liabilities,  certain  debt
service   contract  assistance  payment   to  Massachusetts  Bay  Transportation
Authority  ($205.5  million  projected   in  fiscal  1996),  the   Massachusetts
Convention  Center ($24.6 million  projected in fiscal  1996), the Massachusetts
Government Land Bank ($6.0 million projected in fiscal 1996), the  Massachusetts
Water  Pollution Abatement Trust  ($16.6 million projected  in fiscal 1996), and
grants to municipalities under the school building assistance program to  defray
a  portion  of the  debt service  costs  on local  school bonds  ($174.5 million
projected in fiscal 1996).
 
    In January 1990, legislation  was passed to impose  a limit on debt  service
beginning  in  fiscal  1991,  providing  that no  more  than  10%  of  the total
appropriations in any fiscal  year may be expended  for payment of interest  and
principal  on general obligation debt (excluding the Fiscal Recovery Bonds). The
percentage of total  appropriations expended from  the budgeted operating  funds
for  debt service (excluding  debt service on Fiscal  Recovery Bonds) for fiscal
1994 is 5.6%, which is projected to increase to 5.9% in fiscal 1995.
 
    CERTAIN  LIABILITIES.    Among  the  material  future  liabilities  of   the
Commonwealth  are  significant unfunded  general  liabilities of  its retirement
systems and a program to fund  such liabilities; a program whereby, starting  in
1978,  the  Commonwealth began  assuming full  financial responsibility  for all
costs of  the  administration of  justice  within the  Commonwealth;  continuing
demands to raise aggregate aid to cities, towns, schools and other districts and
transit
 
                                      A-4
<PAGE>
authorities above current levels; and Medicaid expenditures which have increased
each  year since the program was  initiated. The Commonwealth has signed consent
decrees to continue improving mental health  care and programs for the  mentally
retarded  in order to meet federal  standards, including those governing receipt
of federal reimbursements under various programs, and the parties in those cases
have worked cooperatively to resolve the disputed issues.
 
    As a  result of  comprehensive legislation  approved in  January, 1988,  the
Commonwealth  is  required,  beginning in  fiscal  1989 to  fund  future pension
liabilities currently and  to amortize the  Commonwealth's unfunded  liabilities
over  40 years. The funding schedule must provide for annual payments in each of
the ten years ending fiscal 1998 which are at least equal to the total estimated
pay-as-you-go pension costs in each year.  As a result of this requirement,  the
funding  requirements  for  fiscal 1996,  1997,  and  1998 are  estimates  to be
increased to approximately  $1.007 billion, $1.061  billion and $1.128  billion,
respectively.
 
    LITIGATION.    The Commonwealth  is  engaged in  various  lawsuits involving
environmental and related  laws, including an  action brought on  behalf of  the
U.S.  Environmental Protection Agency alleging violations of the Clean Water Act
and seeking to  enforce the clean-up  of Boston Harbor.  The MWRA, successor  in
liability   to  the  Metropolitan  District   Commission,  has  assumed  primary
responsibility for developing  and implementing  a court-approved  plan for  the
construction  of the treatment  facilities necessary to  achieve compliance with
federal requirements. Under the Clean Water Act, the Commonwealth may be  liable
for costs of compliance in these or any other Clean Water cases if the MWRA or a
municipality  is  prevented from  raising revenues  necessary  to comply  with a
judgment. The MWRA currently projects that the total cost of construction of the
treatment facilities required  under the court's  order is approximately  $3.557
billion  in current dollars, with approximately $1.046 billion to be spent on or
after June 30,  1995. On  October 18,  1995, the  court entered  an order  which
reduced  the MWRA's obligation  to build certain  additional secondary treatment
facilities, which is estimated  by the MWRA  will save ratepayers  approximately
$165 million.
 
    The  Department of  Public Welfare  has been  sued for  the alleged unlawful
denial  of  personal  care  attendant  services  to  certain  disabled  Medicaid
recipients. The Superior Court has denied the plaintiff's motion for preliminary
injunction  and has also denied the  plaintiff's motion for class certification.
If the plaintiffs  were to  prevail on their  claims and  the Commonwealth  were
required  to  provide  all of  the  services  sought by  the  plaintiffs  to all
similarly situated persons, it would  substantially increase the annual cost  to
the  Commonwealth if these  services are eventually  required. The Department of
Public Welfare currently estimates this increase  to be as much as $200  million
per year.
 
    There  are  also  actions  pending in  which  recipients  of  human services
benefits, such as welfare  recipients, the mentally  retarded, the elderly,  the
handicapped,  children, residents of state  hospitals and inmates of corrections
institutions, seek  expanded  levels  of  services and  benefits  and  in  which
providers  of services to such recipients challenge  the rates at which they are
reimbursed by  the Commonwealth.  To  the extent  that  such actions  result  in
judgments requiring the Commonwealth to provide expanded services or benefits or
pay  increased  rates, additional  operating and  capital expenditures  might be
needed to implement such judgments.
 
    In 1995, the Spaulding Rehabilitation Hospital ("Spaulding") filed an action
to enforce an agreement to acquire its property by eminent domain in  connection
with  the Central Artery/Third  Harbor Tunnel Project.  If successful, Spaulding
could recover  the  fair  market  value  of its  property  in  addition  to  its
relocation  costs  with  respect  to  its  personal  property.  The Commonwealth
estimates its potential liability at approximately $50 million.
 
    The Commonwealth faces  an additional potential  liability of  approximately
$40  million in connection with a taking by the Massachusetts Highway Department
related to the relocation of Northern Avenue in Boston.
 
    In addition, there are several tax matters in litigation which could  result
in significant refunds to taxpayers if decisions unfavorable to the Commonwealth
are rendered. In BAYBANK, ET AL. V. COMMISSIONER OF REVENUE, the banks challenge
the  inclusion of income from tax exempt  obligations in the measure of the bank
excise tax. The  Appellate Tax Board  issued findings  of fact and  a report  in
favor  of the Commissioner of Revenue on September 30, 1993. The case is pending
before the Supreme Judicial Court. The potential liability is approximately  $55
million, including similarly situated banks and tax years after 1990.
 
    In  NATIONAL  ASSOCIATION  OF  GOVERNMENT  EMPLOYEES  V.  COMMONWEALTH,  the
Superior  Court  declared  that  a  line  item  in  the  Commonwealth's  general
appropriations   act  for  fiscal  1994  that  increased  the  state  employees'
percentage share  of their  group  health insurance  premiums  from 10%  to  15%
violated  the terms of  several collective bargaining  agreements, and therefore
was invalid under the United States Constitution as regards employees covered by
the agreements. On  February 9,  1995, the  Supreme Judicial  Court vacated  the
Superior  Court's decision and declared  that the fiscal 1994  line item did not
violate the contracts  clause. In June,  1995, the United  States Supreme  Court
denied  the plaintiff's  writ of certiorari.  Several other unions  have filed a
companion suit  asserting that  the premium  increase similarly  violated  other
collective  bargaining agreements.  The latter  suit is  in its  initial stages.
Prior to  the Supreme  Judicial Court's  decision the  Commonwealth's  aggregate
liability is estimated to be approximately $32 million.
 
                                      A-5
<PAGE>
    A  variety of  other civil suits  pending against the  Commonwealth may also
affect its future  liabilities. These include  challenges to the  Commonwealth's
allocation  of school aid under Section 9C of Chapter 29 of the General Laws and
to adopt a state employee furlough program. No prediction is possible as to  the
ultimate outcome of these proceedings.
 
    On  March 22, 1995, the Supreme Judicial Court held in PERINI CORPORATION V.
COMMISSION OF REVENUES that certain deductions from the net worth measure of the
Massachusetts corporate excise  tax violate  the Commerce Clause  of the  United
States  Constitution. On October 2, 1995, the United States Supreme Court denied
the Commonwealth's petition for  writ of certiorari.  The Department of  Revenue
estimates that tax revenues in the amount of $40 to $55 million may be abated as
a result of the Supreme Judicial Court's decision.
 
    Many  factors, in addition to those cited  above, have or may have a bearing
upon the financial condition of the Commonwealth, including social and  economic
conditions, many of which are not within the control of the Commonwealth.
 
    EXPENDITURE  AND TAX LIMITATION  MEASURES.  Limits  have been established on
state tax revenues by legislation approved  by the Governor on October 25,  1986
and  by an initiative petition  approved by the voters  on November 4, 1986. The
Executive Office for Administration and  Finance currently estimates that  state
tax  revenues will not reach the limit imposed by either the initiative petition
or the legislative enactment in fiscal 1992.
 
    Proposition 2 1/2, passed by the voters in 1980, led to large reductions  in
property  taxes, the  major source  of income  for cities  and towns,  and large
increases in state aid to offset such revenue losses. According to the Executive
Office for Administration and Finance, all of the 351 cities and towns have  now
achieved  a property  tax level of  no more  than 2.5% of  full property values.
Under the terms of Proposition 2 1/2, the property tax levy can now be increased
annually for all cities and towns, almost all by 2.5% of the prior fiscal year's
tax  levy  plus  2.5%  of  the  value  of  new  properties  and  of  significant
improvements  to  property.  Legislation  has also  been  enacted  providing for
certain local  option  taxes.  A  voter  initiative  petition  approved  at  the
statewide  general election in November, 1990 further regulates the distribution
of Local Aid of no  less than 40% of  collections from individual income  taxes,
sales  and  use taxes,  corporate excise  taxes,  and the  balance of  the state
lottery  fund.  If   implemented  in  accordance   with  its  terms   (including
appropriation  of the  necessary funds),  the petition  as approved  would shift
several hundred million dollars to direct Local Aid.
 
    OTHER TAX MEASURES.   To provide  revenue to  pay debt service  on both  the
deficit  and  Medicaid-related borrowings  and to  fund certain  direct Medicaid
expenditures, legislation  was enacted  imposing an  additional tax  on  certain
types  of personal income for 1989 and 1990 taxable years at rates of 0.375% and
0.75% respectively, effectively raising the tax  rate of 1989 from 5% to  5.375%
and  for 1990 to 5.75%. Recent legislation has effectively further increased tax
rates to 5.95% for  tax year 1990 to  6.25% for tax year  1991 and returning  to
5.95%  for tax year 1992 and subsequent tax  years. The tax is applicable to all
personal  income   except  income   derived  from   dividends,  capital   gains,
unemployment  compensation,  alimony,  rent, interest,  pensions,  annuities and
IRA/Keogh distributions.  The  income  tax rate  on  other  interest  (excluding
interest  on obligations of  the United States  and of the  Commonwealth and its
subdivisions), dividends  and net  capital  gains (after  a 50%  reduction)  was
increased  from 10% to 12%  for tax year 1990  and subsequent years, by recently
enacted legislation.
 
    ESTATE TAX REVISIONS.   The  fiscal 1993 budget  included legislation  which
gradually phases out the current Massachusetts estate tax and replaces it with a
"sponge  tax" in 1997.  The "sponge tax" is  based on the  maximum amount of the
credit for state taxes allowed for  federal estate tax purposes. The estate  tax
is  phased out  by means  of annual  increases in  the basic  exemption from the
current $200,000  level.  The  exemption  is increased  to  $300,000  for  1993,
$400,000  for 1994, $500,000  for 1995 and  $600,000 for 1996.  In addition, the
legislation includes a full marital  deduction starting July 1, 1994.  Currently
the  marital deduction  is limited  to 50%  of the  Massachusetts adjusted gross
estate. The  static  fiscal impact  of  the phase  out  of the  estate  tax  was
estimated  to be approximately $24.8 million in  fiscal 1994 and is estimated to
be approximately $72.5 million in fiscal 1995.
 
    OTHER ISSUERS OF  MASSACHUSETTS OBLIGATIONS.   There are a  number of  state
agencies,  instrumentalities and political subdivisions of the Commonwealth that
issue Municipal Obligations, some  of which may  be conduit revenue  obligations
payable  from payments  from private  borrowers. These  entities are  subject to
various economic  risks  and  uncertainties,  and  the  credit  quality  of  the
securities  issued  by them  may vary  considerably from  the credit  quality of
obligations backed by the full faith  and credit of the Commonwealth. The  brief
summary above does not address, nor does it attempt to address, any difficulties
and   the  financial  situations   of  those  other   issuers  of  Massachusetts
Obligations.
 
MASSACHUSETTS TAXABLE ESTIMATED CURRENT RETURN TABLE
 
    The following tables show the approximate taxable estimated current  returns
for  individuals  that are  equivalent to  tax-exempt estimated  current returns
under combined Federal and  state taxes, using  published 1998 marginal  Federal
tax  rates and marginal state tax rates  currently available and scheduled to be
in  effect.  The  tables  incorporate  increased  tax  rates  for  higher-income
taxpayers  that were  included in  the Revenue  Reconciliation Act  of 1993. The
combined state and Federal  tax brackets shown reflect  the fact that state  tax
payments    are   currently   deductible   for   Federal   tax   purposes.   The
 
                                      A-6
<PAGE>
Massachusetts state  tax rate  shown is  the rate  at which  interest is  taxed.
Certain  other  types of  income are  taxed at  other rates.  The tables  do not
reflect any  local taxes  or any  taxes other  than personal  income taxes.  The
tables  illustrate what you would  have to earn on  taxable investments to equal
the  tax-exempt  estimated  current  return  for  your  income  tax  bracket.  A
taxpayer's  marginal tax  rate is  affected by both  his taxable  income and his
adjusted gross income. Locate your adjusted gross and your taxable income (which
is your adjusted gross  income reduced by any  deductions and exemptions),  then
locate  your tax bracket based on joint or single tax filing. Read across to the
equivalent taxable estimated current return you would need to match the tax-free
income.
 
 COMBINED MARGINAL TAX RATES FOR JOINT TAXPAYERS WITH FOUR PERSONAL EXEMPTIONS
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL
    FEDERAL      ADJUSTED      COMBINED
    TAXABLE        GROSS       STATE AND                    TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME        FEDERAL       --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-42.35 $    0-124.50      25.0   %     5.33    5.67    6.00    6.33    6.67    7.00    7.33    7.67
  42.35-102.30      0-124.50      36.5         6.30    6.69    7.09    7.48    7.87    8.27    8.66    9.06
               124.50-186.80      37.5         6.40    6.80    7.20    7.60    8.00    8.40    8.80    9.20
 102.30-155.95      0-124.50      39.5         6.61    7.02    7.44    7.85    8.26    8.68    9.09    9.50
               124.50-186.80      40.0         6.67    7.08    7.50    7.92    8.33    8.75    9.17    9.58
               186.80-309.30      42.5         6.96    7.39    7.83    8.26    8.70    9.13    9.57   10.00
 155.95-278.45 124.50-186.80      44.5         7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
               186.80-309.30      47.5         7.62    8.10    8.57    9.05    9.52   10.00   10.48   10.95
                 Over 309.30      44.5   2     7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
   Over 278.45 186.80-309.30      51.0         8.16    8.67    9.18    9.69   10.20   10.71   11.22   11.73
                 Over 309.30      48.0   3     7.69    8.17    8.65    9.13    9.62   10.10   10.58   11.06
</TABLE>
 
  COMBINED MARGINAL TAX RATES FOR SINGLE TAXPAYERS WITH ONE PERSONAL EXEMPTION
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL
    FEDERAL      ADJUSTED      COMBINED
    TAXABLE        GROSS       STATE AND                    TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME        FEDERAL       --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-25.35 $    0-124.50      25.0   %     5.33    5.67    6.00    6.33    6.67    7.00    7.33    7.67
   25.35-61.40      0-124.50      36.5         6.30    6.69    7.09    7.48    7.87    8.27    8.66    9.06
  61.40-128.10      0-124.50      39.5         6.61    7.02    7.44    7.85    8.26    8.68    9.09    9.50
                124.50-247.0      40.5         6.72    7.14    7.56    7.98    8.40    8.82    9.24    9.66
 128.10-278.45  124.50-247.0      45.5         7.34    7.80    8.26    8.72    9.17    9.63   10.09   10.55
                  Over 247.0      44.5   2     7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
   Over 278.45    Over 247.0      48.0   3     7.69    8.17    8.65    9.13    9.62   10.10   10.58   11.06
</TABLE>
 
- ------------------
 
       1 The table reflects the effect of the limitations on itemized deductions
and the  deduction for  personal exemptions.  They were  designed to  phase  out
certain  benefits  of  these  deductions  for  higher  income  taxpayers.  These
limitations, in effect, raise  the current maximum  marginal combined state  and
Federal  tax rate  to approximately 50.90  percent for taxpayers  filing a joint
return and  entitled to  four  personal exemptions  and to  approximately  47.90
percent  for  taxpayers filing  a single  return entitled  to only  one personal
exemption. These limitations are  subject to certain  maximums, which depend  on
the number of exemptions claimed and the total amount of the taxpayer's itemized
deductions.  For example, the limitation on itemized deductions will not cause a
taxpayer to  lose more  than  80% of  his  allowable itemized  deductions,  with
certain exceptions.
 
       2 Combined state and Federal tax rate reverts to 43.68% after the 80% cap
on the limitation on itemized deductions has been met.
 
       3 Combined state and Federal tax rate reverts to 46.85% after the 80% cap
on the limitation on itemized deductions has been met.
 
                                      A-7
<PAGE>
                                   APPENDIX B
                              NEW YORK DISCLOSURE
 
ECONOMIC FACTORS--NEW YORK
 
    The  Portfolio of the New York  Insured Trust includes obligations issued by
New York State  (the "State"), by  its various public  bodies (the  "Agencies"),
and/or  by other entities  located within the  State, including the  City of New
York (the "City").
 
    Some of the more significant events and conditions relating to the financial
situation in New York are summarized  below. This section provides only a  brief
summary of the complex factors affecting the financial situation in New York and
is  derived  from  sources that  are  generally  available to  investors  and is
believed to  be  accurate.  It is  based  in  part on  Official  Statements  and
prospectuses issued by, and on other information reported by the State, the City
and the Agencies in connection with the issuance of their respective securities.
 
    There  can  be no  assurance that  current or  future statewide  or regional
economic difficulties, and  the resulting  impact on State  or local  government
finances  generally,  will not  adversely affect  the market  value of  New York
Municipal Obligations  held in  the portfolio  of the  Trust or  the ability  of
particular  obligors to make timely payments of debt service on (or relating to)
those obligations.
 
    (1) THE STATE: The State has historically been one of the wealthiest  states
in  the nation. For  decades, however, the  State economy has  grown more slowly
than that  of the  nation as  a whole,  gradually eroding  the State's  relative
economic  affluence.  Statewide,  urban  centers  have  experienced  significant
changes involving migration of the more affluent to the suburbs and an influx of
generally less affluent residents. Regionally,  the older Northeast cities  have
suffered because of the relative success that the South and the West have had in
attracting  people  and  business.  The  City  has  also  had  to  face  greater
competition  as  other  major  cities  have  developed  financial  and  business
capabilities  which  make  them  less  dependent  on  the  specialized  services
traditionally available almost exclusively in the City.
 
    The State has  for many years  had a very  high state and  local tax  burden
relative to other states. The burden of State and local taxation, in combination
with  the many other causes of regional economic dislocation, has contributed to
the decisions of  some businesses and  individuals to relocate  outside, or  not
locate within, the State.
 
    SLOWDOWN  OF REGIONAL ECONOMY.  A national recession  commenced in mid-1990.
The downturn  continued  throughout the  State's  1990-91 fiscal  year  and  was
followed  by a period of weak economic growth during the 1991 calendar year. For
calendar year 1992,  the national economy  continued to recover,  although at  a
rate  below all  post-war recoveries. For  calendar year 1993,  the economy grew
faster than in 1992,  but still at  a very moderate rate,  as compared to  other
recoveries.  Moderate economic growth continued in calendar year 1994. The State
has projected the rate of economic growth  to slow within New York during  1995,
as  the expansion of  the national economy  moderates. Economic recovery started
considerably later in the State than in the nation as a whole due in part to the
significant retrenchment  in  the  banking and  financial  services  industries,
downsizing  by several major corporations, cutbacks  in defense spending, and an
oversupply of office buildings.  Many uncertainties exist  in forecasts of  both
the  national and State economies  and there can be  no assurance that the State
economy will perform at  a level sufficient to  meet the State's projections  of
receipts and disbursements.
 
    1995-96  FISCAL YEAR.   The Governor issued a  proposed Executive Budget for
the 1995-96  fiscal year  (the "Proposed  Budget") on  February 1,  1995,  which
projected  a  balanced  general fund  and  receipts and  disbursements  of $32.5
billion and  $32.4  billion,  respectively.  As  of  May  29,  1995,  the  State
legislature  had  not yet  enacted,  nor had  the  Governor and  the legislature
reached an agreement on, the budget for the 1995-96 fiscal year which  commenced
on April 1, 1995. The delay in the enactment of the budget may negatively affect
certain proposed actions and reduce projected savings.
 
    The  Proposed Budget and the 1995-96  Financial Plan provide for the closing
of  a  projected  $4.7  billion  budget  gap  in  the  1995-96  fiscal  year  by
cost-containment  savings in social welfare  programs, savings from State agency
restructurings, freezing  the level  of some  categories of  local aid  and  new
revenue measures.
 
    The  State's proposed budget and the 1995-96 Plan may be impacted negatively
by uncertainties relating to  the economy and  tax collections, although  recent
signs  of improvement in the national economy could lead to short-term increases
in State receipts.
 
    1994-1995 FISCAL YEAR.   The State Legislature  enacted the State's  1994-95
fiscal year budget on June 7, 1994, more than two months after the start of that
fiscal  year. As of February  1, 1995, the updated  1994-95 State Financial Plan
(the "Plan") projected total  general fund receipts  and disbursements of  $33.3
billion and $33.5 billion, respectively, representing reductions in receipts and
disbursements  of $1 billion and $743 million, respectively, from the amount set
forth in the 1994-95 budget.  The Plan projected for  a General Fund balance  of
approximately $157 million at the close of the 1994-95 fiscal year.
 
    1993-94  FISCAL  YEAR.   The State  ended  the 1993-94  fiscal year  with an
operating surplus of approximately $1.0 billion.
 
                                      B-1
<PAGE>
    FUTURE FISCAL YEARS. There can be no assurance that the State will not  face
substantial  potential budget  gaps in the  future resulting  from a significant
disparity between tax revenues  projected from a  lower recurring receipts  base
and  the  spending required  to maintain  State programs  at current  levels. To
address  any  potential  budgetary  imbalance,  the  State  may  need  to   take
significant actions to align recurring receipts and disbursements.
 
    INDEBTEDNESS.  As of  March 31,  1994, the  total amount  of long-term State
general obligation debt authorized but unissued stood at $2.0 billion. As of the
same date, the State had approximately $5.4 billion in general obligation  bonds
including $224 million of Bond Anticipation Notes outstanding.
 
    The  State  originally projected  that its  borrowings for  capital purposes
during the State's 1994-95 fiscal year would consist of $374 million in  general
obligation  bonds  and  bond  anticipation notes  and  $140  million  in general
obligation commercial paper. The Legislature  has authorized the issuance of  up
to $69 million in certificates of participation in pools of leases for equipment
and  real property to be utilized by State agencies. Through March 15, 1995, the
State had  issued in  excess of  $590 million  of its  general obligation  bonds
(including  $430  million  of refunding  bonds).  The projections  of  the State
regarding its borrowings  for any fiscal  year are subject  to change if  actual
receipts fall short of State projections or if other circumstances require.
 
    In  June  1990,  legislation  was  enacted  creating  the  "New  York  Local
Government  Assistance  Corporation"  ("LGAC"),  a  public  benefit  corporation
empowered  to  issue long-term  obligations to  fund  certain payments  to local
governments traditionally funded through the State's annual seasonal  borrowing.
As  of March 31, 1994, LGAC has issued its bonds to provide net proceeds of $4.5
billion. The LGAC was authorized to provide net proceeds of $315 million, during
the State's 1994-95 fiscal year. The LGAC issued $347 million of bonds on  March
1, 1995 providing the authorized net proceeds.
 
    Financing  of capital programs  by other public authorities  of the State is
also  obtained   from   lease-purchase  and   contractual-obligation   financing
arrangements,  the debt service for which  is paid from State appropriations. As
of March 31, 1994, there were $16.6 billion of such other financing arrangements
outstanding and additional financings of  this nature by public authorities  are
projected  to total  $2.4 billion during  the 1994-95 fiscal  year. In addition,
certain agencies had issued and outstanding approximately $7.3 billion of "moral
obligation financings" as of March 31, 1994, which are to be repaid from project
revenues. While there has never been a  default on moral obligation debt of  the
State, the State would be required to make up any shortfall in debt service.
 
    RATINGS.   The $850 million in TRANS issued  by the State in April 1993 were
rated SP-1-Plus by S&P and MIG-1 by Moody's which represent the highest  ratings
given  by such agencies and the first time the State's TRANS have received these
ratings since  its May  1989 TRANS  issuance. Both  agencies cited  the  State's
improved  fiscal position as a significant factor  in the upgrading of the April
1993 TRANS.
 
    Moody's rating  of  the State's  general  obligation  bonds stood  at  A  on
February  28, 1994,  and S&P's  rating stood  at A-  with a  positive outlook on
February 28, 1994,  an improvement  from S&P's  stable outlook  from April  1993
through  February 1994  and negative  outlook prior  to April  1993. Previously,
Moody's lowered its rating to A on June 6, 1990, its rating having been A1 since
May 27, 1986. S&P  lowered its rating from  A to A- on  January 13, 1992.  S&P's
previous ratings were A from March 1990 to January 1992, AA- from August 1987 to
March 1990 and A+ from November 1982 to August 1987.
 
    Moody's  maintained  its  A  rating  and  S&P  continued  its  A-  rating in
connection with the State's issuance of  $537 million of its general  obligation
bonds in March 1995.
 
    (2)  THE CITY  AND THE  MUNICIPAL ASSISTANCE  CORPORATION ("MAC"):  The City
accounts for approximately 40%  of the State's  population and personal  income,
and the City's financial health affects the State in numerous ways.
 
    In  response to the City's fiscal crisis in 1975, the State took a number of
steps to assist the City in returning to fiscal stability. Among other  actions,
the State Legislature (i) created MAC to assist with long-term financing for the
City's  short-term debt and  other cash requirements and  (ii) created the State
Financial Control Board (the "Control Board")  to review and approve the  City's
budgets  and City four-year  financial plans (the financial  plans also apply to
certain City-related public agencies (the "Covered Organizations")).
 
    In  recent  years,  the  rate  of   economic  growth  in  the  City   slowed
substantially  as the City's economy entered a recession. While by some measures
the City's economy  may have begun  to recover, a  number of factors,  including
poor  performance  by the  City's financial  services  companies, may  prevent a
significant improvement in the City's economy and may in fact negatively  impact
upon  the City's  finances by  reducing tax  receipts. The  City Comptroller has
issued reports  concluding that  the  recession of  the  City's economy  may  be
ending,  but there is little prospect of any significant improvement in the near
term.
 
    FISCAL YEAR 1996 AND  THE 1995-1998 FINANCIAL PLAN.   On February 14,  1995,
the  Mayor released his  preliminary $30.5 billion budget  for fiscal year 1996,
which included $2.7 billion of deficit reduction measures. The Mayor is  seeking
a  $1.2 billion reduction in mandated welfare and Medicaid expenditures from the
State, a $569 million reduction in  expenditures by city agencies and the  Board
of  Education budget, $600  million in personnel  related savings partly through
the elimination of 15,000 jobs within 18 months, and other measures.
 
                                      B-2
<PAGE>
    The 1995-1998  Financial  Plan (the  "Plan"),  which was  submitted  to  the
Control  Board on February 23,  1995, projected budget gaps  of $3.2 billion and
$3.8 billion for fiscal years 1997 and 1998, respectively. The City  Comptroller
warned  on March 7, 1995 that the budget gap for fiscal year 1996 could increase
by $500 million to as much as $3.2 billion. The Control Board reported on  March
17,  1995 that the proposed budget for  fiscal year 1996 relies heavily on risky
assumptions such as $600  million in savings to  be negotiated with City  unions
and $1.4 billion in savings dependent on State legislative approval.
 
    The  City successfully  negotiated concessions  with a  number of  unions in
order to ensure that the fiscal year 1995 budget remained in balance. The  Mayor
has indicated that to avoid additional lay-offs, higher than the number referred
to above, reductions will be necessary in the benefit plans of City employees to
close the budget gaps for fiscal years 1996 and thereafter. Union leadership has
publicly opposed such "givebacks". With respect to fiscal year 1995 the City was
also  successful in obtaining additional funds  and relief from certain mandated
expenditures from the State for  various programs, including Medicaid.  However,
the  amount of gap closing measures requiring State action set forth in the Plan
is well in excess of proposed assistance to the City outlined in the  Governor's
Proposed Budget.
 
    The  Mayor has directed City agencies to identify an additional $300 million
in cuts for fiscal  year 1996 because  of anticipated shortfalls  of as much  as
$500  million in State aid and budgetary actions. An extended delay by the State
in adopting its  1995-96 fiscal  year budget  would negatively  impact upon  the
City's  financial condition  and ability to  close budget gaps  for fiscal years
1996 and thereafter.
 
    Given the foregoing factors,  there can be no  assurance that the City  will
continue  to maintain  a balanced  budget, or  that it  can maintain  a balanced
budget without additional tax or other  revenue increases or reductions in  City
services, which could adversely affect the City's economic base.
 
    Pursuant  to State law, the City prepares a four-year annual financial plan,
which is reviewed and revised on a quarterly basis and which includes the City's
capital, revenue and  expense projections. The  City is required  to submit  its
financial  plans to review bodies, including the Control Board. If the City were
to experience certain adverse financial circumstances, including the  occurrence
or  the  substantial likelihood  and imminence  of the  occurrence of  an annual
operating deficit of more than $100 million or the loss of access to the  public
credit   markets  to   satisfy  the   City's  capital   and  seasonal  financial
requirements, the  Control Board  would be  required by  State law  to  exercise
certain  powers,  including prior  approval  of City  financial  plans, proposed
borrowings and certain contracts.
 
    The City depends  on the  State for  State aid both  to enable  the City  to
balance  its budget and to meet its  cash requirements. If the State experiences
revenue shortfalls  or  spending increases  beyond  its projections  during  its
1995-96  fiscal  year or  subsequent years,  such  developments could  result in
reductions in projected  State aid to  the City.  In addition, there  can be  no
assurance  that State  budgets in  the 1996-97  or future  fiscal years  will be
adopted by the April  1 statutory deadline  and that there  will not be  adverse
effects  on the City's cash flow and additional City expenditures as a result of
such delays.
 
    The City projections set forth in the Plan are based on various  assumptions
and  contingencies which are uncertain and which may not materialize. Changes in
major assumptions could significantly affect  the City's ability to balance  its
budget  as required by State law and to  meet its annual cash flow and financing
requirements. Such  assumptions  and contingencies  include  the timing  of  any
regional and local economic recovery, the absence of wage increases in excess of
the  increases assumed  in its financial  plan, employment  growth, provision of
State and Federal aid and mandate  relief, State legislative approval of  future
State budgets, levels of education expenditures as may be required by State law,
adoption  of future City budgets  by the New York  City Council, and approval by
the Governor or the State Legislature and the cooperation of MAC with respect to
various other actions proposed in the Plan.
 
    The City's ability to maintain a  balanced operating budget is dependant  on
whether  it  can implement  necessary service  and personnel  reduction programs
successfully. As discussed above, the City must identify additional  expenditure
reductions  and revenue sources to achieve balanced operating budgets for fiscal
years 1996  and thereafter.  Any such  proposed expenditure  reductions will  be
difficult  to implement  because of their  size and  the substantial expenditure
reductions already imposed on City operations in the past two years.
 
    Attaining a balanced  budget is also  dependent upon the  City's ability  to
market  its securities  successfully in  the public  credit markets.  The City's
financing program  for  fiscal  years 1995  through  1998  contemplates  capital
spending  of $16.4  billion, which  will be  financed through  issuance of $10.7
billion of  general obligation  bonds and  the balance  through Water  Authority
Revenue  Bonds  and  Covered  Organization  obligations,  and  will  be utilized
primarily to reconstruct and rehabilitate the City's infrastructure and physical
assets and  to make  capital investments.  A significant  portion of  such  bond
financing  is used to reimburse the City's general fund for capital expenditures
already incurred.  In addition,  the City  issues revenue  and tax  anticipation
notes  to  finance  its seasonal  working  capital requirements.  The  terms and
success of projected  public sales of  City general obligation  bonds and  notes
will  be subject to prevailing market conditions at the time of the sale, and no
assurance can be given that the credit markets will absorb the projected amounts
of public bond and note sales.  In addition, future developments concerning  the
City  and public  discussion of such  developments, the  City's future financial
needs and  other issues  may  affect the  market  for outstanding  City  general
obligation bonds and
 
                                      B-3
<PAGE>
notes.  If the City were unable to  sell its general obligation bonds and notes,
it  would  be  prevented  from   meeting  its  planned  operating  and   capital
expenditures.
 
    FISCAL YEAR 1995.  New York City adopted its fiscal year 1995 budget on June
21,  1994, which provided for spending of  $31.6 billion and closed a budget gap
of $2.3 billion.  However, following adoption  of the fiscal  year 1995  budget,
additional  unexpected  budget  gaps totaling  approximately  $2.0  billion were
identified. The widening of  the budget gap for  fiscal year 1995 resulted  from
shortfalls  in tax revenues  and State and  federal aid. The  Mayor and the City
Council were unable to reach agreement on additional cuts proposed by the  Mayor
in October 1994. The City Council passed its own budget cut proposal in November
1994.  The Mayor vetoed the City Council  version, the City Council overrode his
veto and the Mayor implemented his original plan. A state court held in December
1994 that  neither budget  cut proposal  could be  implemented. The  Mayor  then
elected not to spend certain funds in order to keep the budget in balance.
 
    FISCAL  YEARS  1990  THROUGH 1994.    The City  achieved  balanced operating
results as reported in  accordance with GAAP for  its fiscal years 1990  through
1994.  The City was  required to close  substantial budget gaps  in these fiscal
years to maintain balanced operating results.
 
    The City is a defendant in a significant number of lawsuits. Such litigation
includes, but is not limited to,  actions commenced and claims asserted  against
the  City arising out  of alleged constitutional  violations, torts, breaches of
contracts, and other violations of  law and condemnation proceedings. While  the
ultimate  outcome and fiscal impact,  if any, on the  proceedings and claims are
not currently predictable, adverse determinations in certain of them might  have
a  material adverse effect  upon the City's  ability to carry  out its financial
plan. As of June 30, 1994, the City estimated its potential future liability  to
be $2.6 billion.
 
    On  January  30, 1995,  Robert L.  Schulz and  other defendants  commenced a
federal district court action seeking among other matters to cancel the issuance
on January 31, 1995 of $659 million of City bonds. While the federal courts have
rejected requests for  temporary restraining orders  and expedited appeals,  the
case  is still pending. The City has indicated that it believes the action to be
without merit as it relates to the City, but there can be no assurance as to the
outcome of the litigation and an adverse  ruling or the granting of a  permanent
injunction  would have a  negative impact on the  City's financial condition and
its ability to fund its operations.
 
    RATINGS.  As of the  date of this prospectus,  Moody's rating of the  City's
general  obligation  bonds stood  at Baa1  and  S&P's rating  stood at  BBB+. On
February 11, 1991,  Moody's had  lowered its rating  from A.  S&P's lowered  its
rating  from A-  on July  10, 1995  after placing  the City  on "negative credit
watch" in January 1995.
 
    On March 13, 1995,  Moody's confirmed its Baa1  rating in connection with  a
scheduled  March  1995 sale  of $795  million of  the City's  general obligation
bonds.
 
    In dropping  the City's  rating in  July 1995,  S&P's cited  the  "sluggish"
economy  and the poor  outlook for job growth,  as well as  the continued use of
"one-time measures" to close budget gaps. The lowered rating could increase  the
City's borrowing costs by forcing it to offer higher interest rates on its bonds
thereby adding further pressures to the City's budget problems. In addition, the
lowered  rating may prevent certain  institutional investors from purchasing the
City's bonds reducing demand  for future offerings, which  could also force  the
City to increase interest rates on its bonds.
 
    On  October 12, 1993, Moody's increased its rating of the City's issuance of
$650 million of Tax  Anticipation Notes ("TANs") to  MIG-1 from MIG-2. Prior  to
that  date, on May 9,  1990, Moody's revised downward  its rating on outstanding
City revenue anticipation notes from MIG-1  to MIG-2 and rated the $900  million
Notes  then  being sold  MIG-2.  S&P's rating  of  the October  1993  TANS issue
increased to SP-1 from SP-2. Prior to that date, on April 29, 1991, S&P  revised
downward its rating on City revenue anticipation notes from SP-1 to SP-2.
 
    As  of December 31, 1994, the City  and MAC had, respectively, $22.5 billion
and $4.1 billion of outstanding net long-term indebtedness.
 
    (3) THE STATE AGENCIES: Certain Agencies of the State have faced substantial
financial difficulties which could adversely affect the ability of such Agencies
to make payments  of interest  on, and  principal amounts  of, their  respective
bonds.  The  difficulties  have in  certain  instances caused  the  State (under
so-called  "moral  obligation"  provisions   which  are  non-binding   statutory
provisions  for State  appropriations to  maintain various  debt service reserve
funds) to appropriate funds on behalf of the Agencies. Moreover, it is  expected
that  the  problems  faced by  these  Agencies  will continue  and  will require
increasing amounts of State assistance in future years. Failure of the State  to
appropriate  necessary amounts or to take  other action to permit those Agencies
having financial  difficulties  to meet  their  obligations could  result  in  a
default by one or more of the Agencies. Such default, if it were to occur, would
be  likely to have a  significant adverse effect on  investor confidence in, and
therefore the  market  price of,  obligations  of the  defaulting  Agencies.  In
addition,  any default in payment on any  general obligation of any Agency whose
bonds contain a moral obligation provision could constitute a failure of certain
conditions that must be satisfied in connection with Federal guarantees of  City
and  MAC obligations  and could thus  jeopardize the  City's long-term financing
plans.
 
    As of  September 30,  1993,  the State  reported  that there  were  eighteen
Agencies that each had outstanding debt of $100 million or more and an aggregate
of  $63.5 billion of outstanding debt, some of which was state-supported, state-
related debt.
 
                                      B-4
<PAGE>
    (4) STATE LITIGATION: The State is a defendant in numerous legal proceedings
pertaining to  matters incidental  to the  performance of  routine  governmental
operations.  Such litigation  includes, but is  not limited  to, claims asserted
against the State  arising from  alleged torts, alleged  breaches of  contracts,
condemnation proceedings and other alleged violations of State and Federal laws.
Included in the State's outstanding litigation are a number of cases challenging
the  constitutionality  or  the  adequacy  and  effectiveness  of  a  variety of
significant social  welfare  programs  primarily involving  the  State's  mental
hygiene  programs. Adverse judgments in these  matters generally could result in
injunctive relief coupled with prospective  changes in patient care which  could
require substantial increased financing of the litigated programs in the future.
 
    The  State  is  also engaged  in  a  variety of  claims  wherein significant
monetary damages are sought. Actions  commenced by several Indian nations  claim
that  significant amounts of land were unconstitutionally taken from the Indians
in violation  of  various treaties  and  agreements during  the  eighteenth  and
nineteenth  centuries. The claimants seek  recovery of approximately six million
acres of land as well as compensatory and punitive damages.
 
    The  State  has   entered  into  a   settlement  agreement  with   Delaware,
Massachusetts  and all other parties with respect  to STATE OF DELAWARE V. STATE
OF NEW  YORK,  an action  by  Delaware and  other  states to  recover  unclaimed
property  from New York-based brokers, which has escheated to the State pursuant
to its ABANDONED  PROPERTY LAW. Annual  payments under this  settlement will  be
made  through the  State's 2002-03  fiscal year  in amounts  not exceeding $48.4
million in any fiscal year subsequent to the State's 1994-95 fiscal year.
 
    In SCHULZ V.  STATE OF  NEW YORK, commenced  May 24,  1993 ("SCHULZ  1993"),
petitioners have challenged the constitutionality of mass transportation bonding
programs   of  the  New  York  State  Thruway  Authority  and  the  Metropolitan
Transportation Authority. On  May 24,  1993, the Supreme  Court, Albany  County,
temporarily enjoined the State from implementing those bonding programs.
 
    Petitioners in SCHULZ asserted that issuance of bonds by the two Authorities
is  subject to approval  by statewide referendum. By  decision dated October 21,
1993, the  Appellate  Division, Third  Department,  affirmed the  order  of  the
Supreme  Court, Albany County, granting the State's motion for summary judgment,
dismissing the complaint and vacating  the temporary restraining order. On  June
30,  1994, the Court of Appeals, the State's highest court, upheld the decisions
of the Supreme Court  and Appellate Division in  SCHULZ, Plaintiffs' motion  for
reargument  was denied by  the Court of  Appeals on September  1, 1994 and their
writ of certiorari to the U.S. Supreme Court was denied on January 23, 1995.
 
    Adverse developments in the foregoing  proceedings or new proceedings  could
adversely affect the financial condition of the State in the future.
 
    (5)  OTHER MUNICIPALITIES: Certain  localities in addition  to New York City
could  have  financial  problems  leading  to  requests  for  additional   State
assistance.  The potential impact on the State  of such actions by localities is
not included in projections  of State receipts and  expenditures in the  State's
1994-95 fiscal years.
 
    Fiscal  difficulties experienced by the City of Yonkers ("Yonkers") resulted
in the creation  of the Financial  Control Board  for the City  of Yonkers  (the
"Yonkers  Board")  by the  State  in 1984.  The  Yonkers Board  is  charged with
oversight of the fiscal affairs of Yonkers. Future actions taken by the Governor
or the State Legislature to assist  Yonkers could result in allocation of  State
resources in amounts that cannot yet be determined.
 
    Municipalities  and school districts have  engaged in substantial short-term
and long-term borrowings. In 1992, the  total indebtedness of all localities  in
the  State was approximately $35.2  billion, of which $19.5  billion was debt of
New York  City (excluding  $5.9 billion  in MAC  debt). State  law requires  the
Comptroller  to review and make recommendations  concerning the budgets of those
local government units other than New York City authorized by State law to issue
debt to  finance deficits  during  the period  that  such deficit  financing  is
outstanding.   Seventeen  localities  had  outstanding  indebtedness  for  state
financing at the close of their fiscal year ending in 1992.
 
    Certain proposed Federal  expenditure reductions  could reduce,  or in  some
cases  eliminate, Federal funding  of some local  programs and accordingly might
impose substantial increased expenditure requirements on affected localities. If
the State, New York City or any of the Agencies were to suffer serious financial
difficulties jeopardizing their respective access to the public credit  markets,
the  marketability of  notes and  bonds issued  by localities  within the State,
including notes  or bonds  in the  New York  Insured Trust,  could be  adversely
affected. Localities also face anticipated and potential problems resulting from
certain  pending litigation, judicial decisions, and long-range economic trends.
The longer-range potential  problems of declining  urban population,  increasing
expenditures,  and other economic  trends could adversely  affect localities and
require increasing State assistance in the future.
 
    (6) OTHER ISSUERS OF NEW YORK  MUNICIPAL OBLIGATIONS. There are a number  of
other  agencies, instrumentalities and political  subdivisions of the State that
issue Municipal Obligations, some  of which may  be conduit revenue  obligations
payable  from payments  from private  borrowers. These  entities are  subject to
various economic  risks  and  uncertainties,  and  the  credit  quality  of  the
securities  issued  by them  may vary  considerably from  the credit  quality of
obligations backed by the full faith and credit of the State.
 
                                      B-5
<PAGE>
NEW YORK TAXABLE ESTIMATED CURRENT RETURN TABLE
 
   
    The following tables show the approximate taxable estimated current  returns
for  individuals  that are  equivalent to  tax-exempt estimated  current returns
under combined Federal and  state taxes, using  published 1998 marginal  Federal
tax  rates and marginal state tax rates  currently available and scheduled to be
in  effect.  The  tables  incorporate  increased  tax  rates  for  higher-income
taxpayers  that were  included in  the Revenue  Reconciliation Act  of 1993. The
tables assume that  federal taxable  income is equal  to state  and city  income
subject to tax and that federal adjusted gross income is equal to state and city
adjusted  gross income, and  for cases in  which more than  one state rate falls
within a Federal  bracket, the state  rate corresponding to  the highest  income
within that Federal bracket is used. The combined state and Federal tax brackets
shown  reflect the  fact that  state tax  payments are  currently deductible for
Federal tax purposes. The tables do not reflect any local taxes, other than  New
York City in Chart II, or any taxes other than personal income taxes. The tables
illustrate  what you  would have  to earn  on taxable  investments to  equal the
tax-exempt estimated current return  for your income  tax bracket. A  taxpayer's
marginal  tax rate is affected by both his taxable income and his adjusted gross
income. Locate  your adjusted  gross  and your  taxable  income (which  is  your
adjusted  gross income  reduced by any  deductions and  exemptions), then locate
your tax  bracket based  on  joint or  single tax  filing.  Read across  to  the
equivalent taxable estimated current return you would need to match the tax-free
income.
    
 
I.  COMBINED FEDERAL AND NEW YORK STATE INCOME TAXES
 
 COMBINED MARGINAL TAX RATES FOR JOINT TAXPAYERS WITH FOUR PERSONAL EXEMPTIONS
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL
    FEDERAL      ADJUSTED      COMBINED
    TAXABLE        GROSS       STATE AND                    TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME        FEDERAL       --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-42.35 $     0-100.0      21.0   %     5.06    5.38    5.70    6.01    6.33    6.65    6.96    7.28
                 100.0-124.5      22.0         5.13    5.45    5.77    6.09    6.41    6.73    7.05    7.37
   42.35-102.3       0-100.0      33.0         5.97    6.34    6.72    7.09    7.46    7.84    8.21    8.58
                 100.0-124.5      34.0         6.06    6.44    6.82    7.20    7.58    7.95    8.33    8.71
                 124.5-150.0      35.0         6.15    6.54    6.92    7.31    7.69    8.08    8.46    8.85
                 150.0-186.8      34.0         6.06    6.44    6.82    7.20    7.58    7.95    8.33    8.71
  102.3-155.95       0-100.0      35.5         6.20    6.59    6.98    7.36    7.75    8.14    8.53    8.91
                 100.0-124.5      37.0         6.35    6.75    7.14    7.54    7.94    8.33    8.73    9.13
                 124.5-150.0      38.0         6.45    6.85    7.26    7.66    8.06    8.47    8.87    9.27
                 150.0-186.8      36.5         6.30    6.69    7.09    7.48    7.87    8.27    8.66    9.06
                 186.8-309.3      39.0         6.56    6.97    7.38    7.79    8.20    8.61    9.02    9.43
 155.95-278.45   124.5-150.0      42.5         6.96    7.39    7.83    8.26    8.70    9.13    9.57   10.00
                 150.0-186.8      41.5         6.84    7.26    7.69    8.12    8.55    8.97    9.40    9.83
                 186.8-309.3      44.5         7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
                  Over 309.3      41.5   2     6.84    7.26    7.69    8.12    8.55    8.97    9.40    9.83
   Over 278.45   186.8-309.3      48.0         7.69    8.17    8.65    9.13    9.62   10.10   10.58   11.06
                  Over 309.3      45.0   3     7.27    7.73    8.18    8.64    9.09    9.55   10.00   10.45
</TABLE>
 
  COMBINED MARGINAL TAX RATES FOR SINGLE TAXPAYERS WITH ONE PERSONAL EXEMPTION
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL
    FEDERAL      ADJUSTED      COMBINED
    TAXABLE        GROSS       STATE AND                    TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME        FEDERAL       --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-25.35 $     0-100.0      21.0   %     5.06    5.38    5.70    6.01    6.33    6.65    6.96    7.28
                 100.0-124.5      21.5         5.10    5.41    5.73    6.05    6.37    6.69    7.01    7.32
    25.35-61.4       0-100.0      33.0         5.97    6.34    6.72    7.09    7.46    7.84    8.21    8.58
                 100.0-124.5      33.5         6.02    6.39    6.77    7.14    7.52    7.89    8.27    8.65
    61.4-128.1       0-100.0      35.5         6.20    6.59    6.98    7.36    7.75    8.14    8.53    8.91
                 100.0-124.5      36.5         6.30    6.69    7.09    7.48    7.87    8.27    8.66    9.06
                 124.5-150.0      38.0         6.45    6.85    7.26    7.66    8.06    8.47    8.87    9.27
                 150.0-247.0      37.5         6.40    6.80    7.20    7.60    8.00    8.40    8.80    9.20
  128.1-278.45   124.5-150.0      42.5         6.96    7.39    7.83    8.26    8.70    9.13    9.57   10.00
                 150.0-247.0      42.0         6.90    7.33    7.76    8.19    8.62    9.05    9.48    9.91
                  Over 247.0      41.5   2     6.84    7.26    7.69    8.12    8.55    8.97    9.40    9.83
   Over 278.45    Over 247.0      45.0   3     7.27    7.73    8.18    8.64    9.09    9.55   10.00   10.45
</TABLE>
 
                                      B-6
<PAGE>
II. COMBINED FEDERAL, NEW YORK STATE AND NEW YORK CITY INCOME TAXES
 
 COMBINED MARGINAL TAX RATES FOR JOINT TAXPAYERS WITH FOUR PERSONAL EXEMPTIONS
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL      COMBINED
    FEDERAL      ADJUSTED       STATE,
    TAXABLE        GROSS         LOCAL                      TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME      AND FEDERAL     --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-42.35 $     0-100.0      24.5   %     5.30    5.63    5.96    6.29    6.62    6.95    7.28    7.62
                 100.0-124.5      26.0         5.41    5.74    6.08    6.42    6.76    7.09    7.43    7.77
   42.35-102.3       0-100.0      36.0         6.25    6.64    7.03    7.42    7.81    8.20    8.59    8.98
                 100.0-124.5      37.5         6.40    6.80    7.20    7.60    8.00    8.40    8.80    9.20
                 124.5-150.0      38.5         6.50    6.91    7.32    7.72    8.13    8.54    8.94    9.35
                 150.0-186.8      37.0         6.35    6.75    7.14    7.54    7.94    8.33    8.73    9.13
  102.3-155.95       0-100.0      39.0         6.56    6.97    7.38    7.79    8.20    8.61    9.02    9.43
                 100.0-124.5      40.0         6.67    7.08    7.50    7.92    8.33    8.75    9.17    9.58
                 124.5-150.0      41.0         6.78    7.20    7.63    8.05    8.47    8.90    9.32    9.75
                 150.0-186.8      40.0         6.67    7.08    7.50    7.92    8.33    8.75    9.17    9.58
                 186.8-309.3      42.0         6.90    7.33    7.76    8.19    8.62    9.05    9.48    9.91
 155.95-278.45   124.5-150.0      45.5         7.34    7.80    8.26    8.72    9.17    9.63   10.09   10.55
                 150.0-186.8      44.5         7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
                 186.8-309.3      47.0         7.55    8.02    8.49    8.96    9.43    9.91   10.38   10.85
                  Over 309.3      44.5   2     7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
   Over 278.45   186.8-309.3      50.5         8.08    8.59    9.09    9.60   10.10   10.61   11.11   11.62
                  Over 309.3      47.5   3     7.62    8.10    8.57    9.05    9.52   10.00   10.48   10.95
</TABLE>
 
  COMBINED MARGINAL TAX RATES FOR SINGLE TAXPAYERS WITH ONE PERSONAL EXEMPTION
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL      COMBINED
    FEDERAL      ADJUSTED       STATE,
    TAXABLE        GROSS         LOCAL                      TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME      AND FEDERAL     --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-25.35 $     0-100.0      24.5   %     5.30    5.63    5.96    6.29    6.62    6.95    7.28    7.62
                 100.0-124.5      25.0         5.33    5.67    6.00    6.33    6.67    7.00    7.33    7.67
    25.35-61.4       0-100.0      36.0         6.25    6.64    7.03    7.42    7.81    8.20    8.59    8.98
                 100.0-124.5      36.5         6.30    6.69    7.09    7.48    7.87    8.27    8.66    9.06
    61.4-128.1       0-100.0      39.0         6.56    6.97    7.38    7.79    8.20    8.61    9.02    9.43
                 100.0-124.5      39.5         6.61    7.02    7.44    7.85    8.26    8.68    9.09    9.50
                 124.5-150.0      41.0         6.78    7.20    7.63    8.05    8.47    8.90    9.32    9.75
                 150.0-247.0      40.5         6.72    7.14    7.56    7.98    8.40    8.82    9.24    9.66
  128.1-278.45   124.5-150.0      45.5         7.34    7.80    8.26    8.72    9.17    9.63   10.09   10.55
                 150.0-247.0      45.0         7.27    7.73    8.18    8.64    9.09    9.55   10.00   10.45
                  Over 247.0      44.5   2     7.21    7.66    8.11    8.56    9.01    9.46    9.91   10.36
   Over 278.45    Over 247.0      47.5   3     7.62    8.10    8.57    9.05    9.52   10.00   10.48   10.95
</TABLE>
 
- ------------------
 
       1  The table reflects  the effect of the  federal limitations on itemized
deductions (and  the corresponding  state limitations)  and the  deductions  for
personal  exemptions. They were designed to  phase out certain benefits of these
deductions for higher income taxpayers. These limitations, in effect, raise  the
marginal  combined Federal and state tax rate to approximately 48.15 percent for
taxpayers filing a joint return and entitled to four personal exemptions and  to
approximately  44.97 percent  for taxpayers filing  a single  return entitled to
only one personal exemption  and, in effect raise  the marginal combined  State,
New  York City and Federal tax rate to approximately 50.71 percent for taxpayers
filing  a  joint  return  and  entitled  to  four  personal  exemptions  and  to
approximately  47.69 percent, for  taxpayers filing a  single return entitled to
only one personal exemption. These limitations are subject to certain  maximums,
which  depend on the  number of exemptions  claimed and the  total amount of the
taxpayer's  itemized  deductions.  For  example,  the  limitation  on   itemized
deductions  will not  cause a taxpayer  to lose  more than 80%  of his allowable
Federal or state itemized  deductions, with certain  exceptions. The table  also
reflects  the New York State supplemental income tax based upon a taxpayer's New
York State  taxable  income and  New  York  State adjusted  gross  income.  This
supplemental  tax results in an increased marginal  state income tax rate to the
extent a taxpayer's New York State adjusted gross income ranges between $100,000
and $150,000. Although the table does reflect the effect of the state limitation
on itemized deductions that corresponds to  the federal limitation, it does  not
reflect  additional limitations under which a New York taxpayer could lose up to
an additional 50 percent of his otherwise allowable itemized deductions, because
the affect of this limitation varies  according to the particular amount of  his
itemized  deductions. The application of  this limit may result  in a higher tax
rate than indicated in the  table for joint taxpayers  with a New York  adjusted
gross income of $200,000 to $250,000 or $475,000 to $525,000 or single taxpayers
with  a New York  adjusted gross income  of $100,000 to  $150,000 or $475,000 to
$525,000. The table  assumes that a  taxpayer's New York  adjusted gross  income
equals  his  Federal  adjusted gross  income.  The  table does  not  reflect the
treatment of various state and city tax  credits that could affect the tax  rate
of particular New York taxpayers.
 
       2  Combined Federal and  state tax rate  reverts to 40.38%  after the 80%
caps on the limitation on itemized deductions has been met. Combined state,  New
York  City and  Federal tax  rate reverts  to 43.24%  after the  80% cap  on the
limitation on itemized deductions has been met.
 
       3 Combined Federal  and state tax  rate reverts to  43.74% after the  80%
caps  on the limitation on itemized deductions has been met. Combined state, New
York City  and Federal  tax rate  reverts to  46.43% after  the 80%  cap on  the
limitation on itemized deductions has been met.
 
                                      B-7
<PAGE>
                                   APPENDIX C
                            PENNSYLVANIA DISCLOSURE
 
ECONOMIC FACTORS--PENNSYLVANIA
 
    RISK   FACTORS--Prospective   investors   should   consider   the  financial
difficulties  and  pressures   that  the  Commonwealth   of  Pennsylvania   (the
"Commonwealth" or "Pennsylvania") and certain of its municipal subdivisions have
undergone.  Both the Commonwealth and the City of Philadelphia have historically
experienced significant revenue shortfalls. There  can be no assurance that  the
Commonwealth will not experience further declines in economic conditions or that
portions of the municipal obligations purchased by the Fund will not be affected
by  such  declines.  Without intending  to  be complete,  the  following briefly
summarizes some of these  difficulties and the  current financial situation,  as
well  as some of  the complex factors  affecting the financial  situation in the
Commonwealth. It  is  derived  from  sources that  are  generally  available  to
investors  and is based in part on information obtained from various agencies in
the Commonwealth. No  independent verification  has been made  of the  following
information.
 
    STATE  ECONOMY--The Commonwealth of Pennsylvania is one of the most populous
states,  ranking  fifth  behind  California,   New  York,  Texas  and   Florida.
Pennsylvania  is an established yet growing state with a diversified economy. It
is the  headquarters  for over  50  major corporations.  Pennsylvania  had  been
historically  identified as a heavy-industry  state. That reputation has changed
over the last thirty years as  the coal, steel and railroad industries  declined
and  the  Commonwealth's  business  environment  readjusted  to  reflect  a more
diversified industrial  base.  This economic  readjustment  was a  result  of  a
long-term  shift in jobs, investment and workers away from the northeast part of
the nation. Currently, the  major sources of growth  in Pennsylvania are in  the
service  sector, including trade, medical and the health services, education and
financial institutions.
 
    Pennsylvania's agricultural industries remain an important component of  the
Commonwealth's economic structure, accounting for more than $3.6 billion in crop
and  livestock  products  annually.  Agribusiness  and  food-related  industries
support $39 billion in  economic activity annually. Over  51,000 farms form  the
backbone  of the State's agricultural economy. Farmland in Pennsylvania includes
over four million acres of harvested cropland and four million acres of  pasture
and  farm woodlands --  nearly one-third of the  Commonwealth's total land area.
Agricultural diversity  in the  Commonwealth is  demonstrated by  the fact  that
Pennsylvania  ranks among the  top ten states  in the production  of a number of
agricultural products.
 
    Non-agricultural employment in  Pennsylvania over  the ten  years ending  in
1996  increased at an annual rate of 1.03  percent. This rate compares to a 0.41
percent rate for  the middle  atlantic region  and a  1.8 percent  rate for  the
United  States during  the period  from 1986  through 1996.  For the  last three
years, employment in the Commonwealth has  increased 3.6 percent. The growth  in
employment experienced in Pennsylvania during this period is higher than the 3.0
percent growth in the middle atlantic region.
 
    Non-manufacturing  employment in Pennsylvania has  increased in recent years
to 82.5  percent  of  total  employment  in  1996.  Consequently,  manufacturing
employment  constitutes  a  diminished  share  of  total  employment  within the
Commonwealth. Manufacturing, contributing 17.5 percent of 1996  non-agricultural
employment  has fallen behind both  the services sector and  the trade sector as
the largest single source  of employment within the  Commonwealth. In 1996,  the
services  sector accounted for  31.1 percent of  all non-agricultural employment
while the trade sector accounted for 22.7 percent.
 
    Pennsylvania's annual  average  unemployment  rate was  below  the  national
average  from 1986  until 1990. Slower  economic growth  caused the unemployment
rate in the Commonwealth to rise to 6.9 percent in 1991 and 7.5 percent in 1992.
The resumption  of  faster  economic  growth  resulted  in  a  decrease  in  the
Commonwealth's  unemployment  rate to  7.1 percent  in 1993.  In 1994  and 1995,
Pennsylvania's annual average  unemployment rate was  below the Middle  Atlantic
Region's  average, but slightly higher than that  of the United States. In 1996,
Pennsylvania's annual average  unemployment rate  was 5.3  percent, whereas  the
annual  average  unemployment rate  in the  United States  was 5.4  percent. For
August 1997, the seasonally adjusted unemployment rate for the Commonwealth  was
5.3 percent compared to 4.9 percent for the United States.
 
    STATE  BUDGET--The  Commonwealth operates  under  an annual  budget  that is
formulated and submitted for legislative approval by the Governor each February.
The Pennsylvania  Constitution  requires  that the  Governor's  budget  proposal
consist  of three parts: (i) a  balanced operating budget setting forth proposed
expenditures and estimated revenues from all sources and, if estimated  revenues
and available surplus are less than proposed expenditures, recommending specific
additional  sources of revenue sufficient to  pay the deficiency; (ii) a capital
budget setting forth proposed expenditures to  be financed from the proceeds  of
obligations  of the  Commonwealth or its  agencies or from  operating funds; and
(iii) a financial plan for not less than the succeeding five fiscal years,  that
includes  for each year projected  operating expenditures and estimated revenues
and projected expenditures for capital  projects. The General Assembly may  add,
change  or delete  any items  in the  budget prepared  by the  Governor, but the
Governor retains veto power over the
 
                                      C-1
<PAGE>
individual appropriations passed by  the legislature. The Commonwealth's  fiscal
year begins on July 1 and ends on June 30.
 
    All  funds  received by  the Commonwealth  are  subject to  appropriation in
specific amounts by the  General Assembly or by  executive authorization by  the
Governor.  Total appropriations enacted  by the General  Assembly may not exceed
the ensuing  year's  estimated revenues,  plus  (less) the  unappropriated  fund
balance  (deficit) of the preceding year, except for constitutionally authorized
debt service payments. Appropriations from the principal operating funds of  the
Commonwealth  (the General  Fund, the Motor  License Fund and  the State Lottery
Fund)  are  generally  made  for  one  fiscal  year  and  are  returned  to  the
unappropriated  surplus of the fund if not spent or encumbered by the end of the
fiscal year. The Constitution specifies that a surplus of operating funds at the
end of a fiscal year must be appropriated for the ensuing year.
 
    Pennsylvania  uses  the  "fund"  method  of  accounting.  For  purposes   of
government  accounting, a "fund" is an  independent fiscal and accounting entity
with a self-balancing  set of  accounts, recording cash  and/or other  resources
together  with all related liabilities and  equities that are segregated for the
purpose of carrying on  specific activities or  attaining certain objectives  in
accordance  with the fund's special regulations, restrictions or limitations. In
the Commonwealth, funds are established  by legislative enactment or in  certain
cases  by administrative  action. Over 150  funds have been  established for the
purpose of recording  the receipt  and disbursement  of moneys  received by  the
Commonwealth.  Annual budgets  are adopted  each fiscal  year for  the principal
operating funds of  the Commonwealth  and several other  special revenue  funds.
Expenditures  and encumbrances against these funds  may only be made pursuant to
appropriation measures  enacted by  the  General Assembly  and approved  by  the
Governor.  The General Fund,  the Commonwealth's largest  fund, receives all tax
revenues, non-tax  revenues and  federal grants  and entitlements  that are  not
specified  by law to be deposited  elsewhere. The majority of the Commonwealth's
operating and administrative expenses  are payable from  the General Fund.  Debt
service  on all  bond indebtedness of  the Commonwealth, except  that issued for
highway purposes or for the benefit  of other special revenue funds, is  payable
from the General Fund.
 
    Financial  information for the principal operating funds of the Commonwealth
are maintained on a budgetary basis of accounting, which is used for the purpose
of ensuring  compliance  with the  enacted  operating budget.  Since  1984,  the
Commonwealth  has also prepared  annual financial statements  in accordance with
generally accepted  accounting principles  ("GAAP"). Budgetary  basis  financial
reports  are  based on  a  modified cash  basis of  accounting  as opposed  to a
modified accrual basis  of accounting  prescribed by GAAP.  The budgetary  basis
financial  information  is adjusted  at fiscal  year-end to  reflect appropriate
accruals for financial reporting in conformity with GAAP.
 
    FINANCIAL CONDITION  AND  RESULTS OF  OPERATIONS.--  The fiscal  years  1992
through  1996 were years of recovery for Pennsylvania from the recession in 1990
and 1991. The recovery fiscal years were characterized by modest economic growth
and low inflation rates in the Commonwealth. These economic conditions, combined
with several years of  tax reductions following the  various tax rate  increases
and  tax base expansions enacted  in fiscal 1991 for  the General Fund, produced
modest increases in Pennsylvania's tax revenues during the period. Tax  revenues
from  fiscal 1992  through fiscal  1996 rose  at an  annual average  rate of 2.8
percent. Total revenues and other income sources increased during this period by
an average annual rate  of 3.3 percent. Expenditures  and other uses during  the
fiscal 1992 through fiscal 1996 period rose at a 4.4 percent annual rate, led by
annual  average increases of 14.2 percent for protection of persons and property
program costs and 11.4 percent for capital outlay costs. Expenditure  reductions
for  fiscal 1996 from the  previous fiscal year for  operating transfers out and
for  conservation  of  natural  resources  program  costs  were  the  result  of
accounting  changes affecting the General Fund and  the Motor License Fund and a
recategorization of  expenditures due  to a  departmental restructuring  in  the
General Fund. At the close of fiscal 1996, the fund balance for the governmental
fund  types totaled $1,986.3  million, an increase of  $58.7 million over fiscal
1995 and $758.5 million over fiscal 1992.
 
    FINANCIAL RESULTS  FOR  RECENT  FISCAL YEARS  (GAAP  BASIS).--The  five-year
period  from  fiscal 1992  through fiscal  1996 recorded  a 4.6  percent average
annual increase in revenues and other sources, led by an average annual increase
of   13.2   percent   for   intergovernmental   revenues.   The   increase   for
intergovernmental revenues in fiscal 1996 is partly due to an accounting change.
Tax  revenues during the five-year period increased an average of 2.5 percent as
modest economic growth, low inflation rates and several tax rate reductions  and
other  tax reduction  measures constrained the  growth of tax  revenues. The tax
reduction measures followed a $2.7 billion tax increase measure adopted for  the
1992 fiscal year.
 
    Expenditures  and  other uses  during the  fiscal  1992 through  fiscal 1996
period rose at an average  annual rate of 6.0 percent  led by increases of  14.2
percent  for protection of  persons and property  program costs. The  costs of a
prison expansion program and other correctional program expenses are responsible
for the  large percentage  increase. A  reduction in  debt service  costs at  an
average  annual rate of  29.1 percent over  the five-year period  is a result of
reduced short-term borrowing for cash flow purposes. Improved financial  results
and  structural  cash flow  modifications  contributed to  the  lower borrowing.
Efforts to control costs for various social welfare programs and the presence of
favorable economic conditions  have led  to a  modest 5.6  percent increase  for
public health and welfare costs for the five year period.
 
                                      C-2
<PAGE>
    The  fund balance at June 30, 1996  totaled $635.2 million, a $547.7 million
increase from a balance of $87.5 million at June 30, 1992 and a slight  decrease
from the June 30, 1995 balance.
 
    FISCAL  1995 FINANCIAL RESULTS (BUDGETARY BASIS).--Commonwealth revenues for
the 1995 fiscal year were above  estimate and exceeded fiscal year  expenditures
and  encumbrances.  Fiscal  1995  was the  fourth  consecutive  fiscal  year the
Commonwealth reported an increase in the fiscal year-end unappropriated balance.
Prior to reserves for transfer to the Tax Stabilization Reserve Fund, the fiscal
1995 closing unappropriated surplus  was $540.0 million,  an increase of  $204.2
million over the fiscal 1994 closing unappropriated surplus prior to transfers.
 
    Commonwealth  revenues during the 1995 fiscal  year were $459.4 million, 2.9
percent, above the estimate of  revenues used at the  time the 1995 fiscal  year
budget  was  enacted.  Corporation  taxes  contributed  $329.4  million  of  the
additional receipts largely due to higher receipts from the corporate net income
tax. Fiscal 1995 revenues  from the corporate net  income tax were 22.6  percent
over  collections in fiscal 1994 and include the effects of the reduction of the
tax rate from  12.25 percent  to 11.99 percent  that became  effective with  tax
years  beginning  on  and after  January  1, 1994.  The  sales and  use  tax and
miscellaneous revenues also  showed strong year-over-year  growth that  produced
above-estimate  revenue collections.  Sales and  use tax  revenues were $5,526.9
million, $128.8 million above the enacted  budget estimate and 7.9 percent  over
fiscal  1994 collections.  Tax receipts  from both  motor vehicle  and non-motor
vehicle sales  contributed  to  the higher  collections.  Miscellaneous  revenue
collections  for fiscal 1995  were $183.5 million,  $44.9 million above estimate
and were largely  due to  additional investment earnings,  escheat revenues  and
other miscellaneous revenues.
 
    FISCAL 1996 FINANCIAL RESULTS (BUDGETARY BASIS).--The unappropriated surplus
for Commonwealth revenues (prior to transfers to Tax Stabilization Reserve Fund)
at  the close of the fiscal year for  the General Fund was $183.8 million, $65.5
million above estimate. Expenditures from  Commonwealth revenues for the  fiscal
year,  including  $113.0 million  of  supplemental appropriations  but excluding
pooled financing expenditures, totaled $16,074.7 million. Expenditures  exceeded
available  revenues and lapses by $253.2 million. The difference was funded from
a planned partial drawdown of the $437.0 million fiscal year adjusted  beginning
unappropriated surplus.
 
    Commonwealth  revenues  (prior  to tax  refunds)  for the  1996  fiscal year
increased by $113.9  million over  the prior  fiscal year  to $16,338.5  million
representing a growth rate of 0.7 percent. Tax rate reductions and other tax law
changes  substantially reduced  the amount  and rate  of revenue  growth for the
fiscal year. The  Commonwealth has estimated  that tax changes  enacted for  the
1996  fiscal year reduced  Commonwealth revenues by  $283.4 million representing
1.7 percentage points of fiscal 1996  growth in Commonwealth revenues. The  most
significant  tax changes enacted for the 1996 fiscal year were (i) the reduction
of the corporate net income  tax rate to 9.99  percent; (ii) double weighing  of
the sales factor of the corporate net income apportionment calculation; (iii) an
increase in the maximum annual allowance for a net operating loss deduction from
$0.5 million to $1.0 million; (iv) an increase in the basic exemption amount for
the capital stock and franchise tax; (v) the repeal of the tax on annuities; and
(vi)  the elimination  of inheritance  tax on  transfers of  certain property to
surviving spouses.
 
    Among the major sources of Commonwealth  revenues for the 1996 fiscal  year,
corporate tax receipts declined $338.4 million from receipts in the prior fiscal
year,  largely due to the various tax changes enacted for these taxes. Corporate
tax changes were enacted  to reduce the cost  of doing business in  Pennsylvania
for  the purpose of encouraging business to remain in Pennsylvania and to expand
employment opportunities within the  state. Sales and use  tax receipts for  the
fiscal  year  increased $155.5  million, or  2.8  percent, over  receipts during
fiscal 1995. All of the increase  was produced by the non-motor vehicle  portion
of  the tax as  receipts from the  sale of motor  vehicles declined slightly for
fiscal 1996. Personal income tax receipts  for the fiscal year increased  $291.1
million,  or 5.7 percent, over receipts  during fiscal 1995. Personal income tax
receipts were aided by  a 10.2 percent increase  in nonwithholding tax  payments
which generally are comprised of quarterly estimated and annual final return tax
payments.  Non-tax receipts for the fiscal  year increased $23.7 million for the
fiscal year. Included in that  increase was $67 million  in net receipts from  a
tax amnesty program that was available for a portion of the 1996 fiscal year.
 
    FISCAL 1997 FINANCIAL RESULTS (BUDGETARY BASIS).--The unappropriated balance
of  Commonwealth  revenues  increased  during the  1997  fiscal  year  by $432.9
million. Higher than  estimated revenues  and slightly  lower expenditures  than
budgeted  caused the increase. The unappropriated  balance rose from an adjusted
amount of $158.5  million at  the beginning of  fiscal 1997,  to $591.4  million
(prior  to reserves for transfer  to the Tax Stabilization  Reserve Fund) at the
close of the fiscal  year. Transfers to the  Tax Stabilization Reserve Fund  for
fiscal  1997 operations are  expected to be $88.7  million, which represents the
normal fifteen percent of the ending unappropriated balance, plus an  additional
$100  million authorized by the General Assembly when it enacted the fiscal 1998
budget.
 
    Commonwealth revenues (prior to tax refunds) during the fiscal year  totaled
$17,320.6  million, $576.1 (3.4 percent) above the estimate made at the time the
budget was enacted.  Revenue from taxes  was the largest  contributor to  higher
than  estimated receipts. Tax revenue  in fiscal 1997 grew  6.1 percent over tax
revenues in fiscal 1996. This rate  of increase was not adjusted for  legislated
tax  reductions that  affected receipts  during both  of those  fiscal years and
therefore
 
                                      C-3
<PAGE>
understates the actual underlying  rate of growth of  tax revenue during  fiscal
1997.  Receipts  from  the  personal  income  tax  produced  the  largest single
component of higher revenues  for the fiscal  year. Personal income  collections
were  $236.3  million over  estimate representing  a  6.9 percent  increase over
fiscal 1996 receipts. Receipts of the sales and use tax were $185.6 million over
estimate representing a  6.2 percent increase.  Collections of corporate  taxes,
led  by  the capital  stock  and franchise  and  the gross  receipt  taxes, also
exceeded their  estimates  for the  fiscal  year. Non-tax  revenues  were  $19.8
million  (5.8  percent)  over estimate  mostly  due to  higher  than anticipated
interest earnings.
 
    Expenditures  from   Commonwealth  revenues   (excluding  pooled   financing
expenditures) during fiscal 1997 totaled $16,347.7 million and were close to the
estimate  made in February  1997 with the presentation  of the Governor's fiscal
1998 budget request. Total expenditures  represent an increase over fiscal  1996
expenditures of 1.7 percent.
 
    FISCAL  1998 BUDGET--The  budget for  fiscal 1998  was enacted  in May 1997.
Commonwealth revenues for  the fiscal  year at that  time were  estimated to  be
$17,435.4  million before reserves for tax refunds. That estimate represented an
increase over  estimated  fiscal  1997 Commonwealth  revenues  of  1.0  percent.
Although  fiscal 1997  revenues exceeded  the fiscal  1997 budget  estimate, the
adopted fiscal 1998 budget revenue  estimate remains unchanged and represents  a
0.7 percent increase over actual fiscal 1997 revenues. Fiscal 1998 estimates for
Commonwealth  revenues are based  on an economic  forecast for national economic
growth to slow through  the remainder of  calendar year 1997.  A growth rate  of
just  above 1.0 percent is anticipated by  the Commonwealth to be maintained for
the last two quarters of the 1998 fiscal year and result in a 1.2 percent growth
rate in real gross domestic product for the second calendar quarter of 1998 over
the second quarter of 1997. This anticipated rate of economic growth is a result
of anticipated slowing of  gains in consumer  spending, business investment  and
residential   housing.  Inflation  is   projected  to  remain   modest  and  the
unemployment rate  is expected  to  reach 6.0  percent  by the  second  calendar
quarter of 1998.
 
    The  rate of anticipated growth of Commonwealth revenues is also affected by
the enactment of tax  reductions and tax revenue  dedications effective for  the
1998  fiscal year. Excluding these newly enacted changes, revenues are projected
to increase by 2.4  percent during fiscal 1998.  Tax reductions enacted for  the
1998  fiscal year  budget totaled an  estimated $170.6  million, including $16.2
million that is  reflected in  higher projected  tax refunds.  In addition,  $75
million  of  existing sales  tax  revenue has  been  earmarked for  mass transit
funding and one cent of the cigarette tax ($10.8 million) has been earmarked for
a children's health  program and  are no longer  included in  the General  Fund.
Major  changes to taxes enacted  for fiscal 1998 include:  (i) the repeal of the
sales and use tax on computer services ($79.1 million); (ii) an increase in  the
amount  of income  that is  exempt from the  personal income  tax for low-income
families ($25.4  million); (iii)  enactment of  a research  and development  tax
credit  program for business ($15.0 million);  (iv) conforming state tax laws to
federal laws for sub-chapter S and limited liability companies ($16.3  million);
and various other miscellaneous changes. Most changes are effective beginning in
July 1997 although some are effective retroactively to January 1997.
 
    Appropriations  enacted for fiscal 1998 are 3.7 percent ($618 million) above
appropriations enacted for fiscal 1997 (including supplemental  appropriations).
Major  funding increases  provided by the  fiscal 1998 budget  include: (i) $166
million of  appropriations  for  elementary  and  secondary  education  plus  an
estimated  $51 million in  reduced employer retirement  contributions payable by
local school districts  due to a  reduction in the  contribution rate; (ii)  $42
million   for  higher  education  institutions  plus  $16  million  for  student
scholarships; (iii) $70 million  for higher caseload,  utilization, and cost  of
nursing  home care; (iv) $60 million for economic development assistance through
programs  providing  incentive  grants  and  loans;  and  (v)  $38  million  for
corrections  including  $17 million  for operating  costs  for new  and expanded
facilities. The balance of  the increase is spread  over many other  departments
and program operations.
 
    Based  on current  expectations and the  adopted budget for  fiscal 1998 and
excluding any  estimate for  appropriation lapses  during the  fiscal year,  the
unappropriated  surplus  is  projected to  decline  from $402.7  million  at the
beginning of  the fiscal  year to  $16.7 million  at fiscal  year-end (prior  to
transfer to the Tax Stabilization Reserve Fund).
 
    DEBT LIMITS AND OUTSTANDING DEBT.--The Pennsylvania Constitution permits the
issuance  of the following types  of debt: (i) debt  to suppress insurrection or
rehabilitate areas affected  by disaster; (ii)  electorate approved debt;  (iii)
debt for capital projects subject to an aggregate outstanding debt limit of 1.75
times  the annual average tax  revenues of the preceding  five fiscal years; and
(iv) tax anticipation notes payable in the fiscal year of issuance.
 
    Under the  Pennsylvania Fiscal  Code,  the Auditor  General is  required  to
certify  to the Governor and the  General Assembly certain information regarding
the Commonwealth's  indebtedness.  According  to the  August  29,  1997  Auditor
General  certificate, the average annual tax  revenues deposited in all funds in
the five  fiscal years  ended June  30, 1997  was approximately  $19.6  billion,
outstanding net debt totaled $3.7 billion at August 31, 1997, and therefore, the
net  debt limitation for  the 1997 fiscal  year is $30.6  billion. At August 29,
1997, the amount of debt authorized by  law to be issued, but not yet  incurred,
was $17.1 billion.
 
    Outstanding  general obligation  debt totaled  $4,795.1 million  at June 30,
1997, a decrease of $261.0 million from June 30, 1996. Over the ten-year  period
ending  June 30, 1997, total outstanding general obligation debt increased at an
annual
 
                                      C-4
<PAGE>
rate of  0.5  percent. Within  the  most recent  five-year  period,  outstanding
general obligation debt has decreased at an annual rate of 0.3 percent.
 
    DEBT  RATINGS.--All outstanding general obligation bonds of the Commonwealth
are rated AA- by Standard & Poor's Corporation, Aa3 by Moody's Investors Service
and AA by Fitch IBCA, Inc. (formerly Fitch Investors Service).
 
    CITY  OF   PHILADELPHIA.--The   City   of  Philadelphia   (the   "City"   or
"Philadelphia")  is  the largest  city in  the  Commonwealth, with  an estimated
population of 1,585,577 according to the 1990 Census. Philadelphia experienced a
series of  general  fund deficits  for  fiscal  years 1988  through  1992  which
culminated  in  serious  financial  difficulties  for  the  City.  In  its  1992
Comprehensive  Annual  Financial  Report,  Philadelphia  reported  a  cumulative
general fund deficit of $71.4 million for fiscal year 1992.
 
    In  June  1991, the  Pennsylvania  legislature established  the Pennsylvania
Intergovernmental Cooperation Authority ("PICA"), a five-member board to  assist
Philadelphia  in  remedying  fiscal  emergencies. PICA  is  designed  to provide
assistance through the issuance of funding debt and to make factual findings and
recommendations to Philadelphia concerning its budgetary and fiscal affairs. The
legislation empowered PICA to issue notes  and bonds on behalf of  Philadelphia,
and also authorized Philadelphia to levy a one-percent sales tax the proceeds of
which  would  be  used  to  pay  off the  bonds.  In  return  for  PICA's fiscal
assistance, Philadelphia is required, among other things, to establish five-year
financial plans that include balanced annual budgets. Under the legislation,  if
Philadelphia  does not  comply with  such requirements,  PICA may  withhold bond
revenues and certain state funding. At this time, the City is operating under  a
five-year  fiscal plan  approved by PICA  on May  20, 1997. As  of September 25,
1997, PICA has issued approximately $1,761.7 million of its Special Tax  Revenue
Bonds.  The  financial assistance  has included  the  refunding of  certain city
general obligation bonds, funding of capital projects and the liquidation of the
City's Cumulative General  Fund balance deficit  as of June  30, 1992 of  $224.9
million.
 
    No  further PICA bonds are to be issued by PICA for the purpose of financing
a capital project or  deficit as the  authority for such  bond sales expired  on
December 31, 1994. PICA's authority to issue debt for the purpose of financing a
cash  flow deficit expired on December 31,  1996. Its ability to refund existing
outstanding debt  is unrestricted.  PICA  had $1,102.4  million in  Special  Tax
Revenue Bonds outstanding as of June 30, 1997.
 
    The  audited General fund balance of the City  as of June 30, 1994, 1995 and
1996 showed a surplus of approximately  $15.4 million, $80.5 million and  $118.5
million, respectively.
 
    S&P's  rating on Philadelphia's general  obligation bonds is "BBB-." Moody's
rating is currently "Baa."
 
    LITIGATION.--The Commonwealth is a  party to numerous  lawsuits in which  an
adverse  final decision could materially  affect the Commonwealth's governmental
operations and consequently its ability to pay debt service on its  obligations.
The  Commonwealth also faces tort claims made  possible by the limited waiver of
sovereign immunity effected by Act 152, approved September 28, 1978, as amended.
Under the Act, damages for  any loss are limited to  $250,000 per person and  $1
million for each accident.
 
PENNSYLVANIA TAXABLE ESTIMATED CURRENT RETURN TABLE
 
    The  following tables show the approximate taxable estimated current returns
for individuals  that are  equivalent to  tax-exempt estimated  current  returns
under  combined Federal and  state taxes, using  published 1998 marginal Federal
tax rates and marginal state tax  rates currently available and scheduled to  be
in  effect.  The  tables  incorporate  increased  tax  rates  for  higher-income
taxpayers that were  included in  the Revenue  Reconciliation Act  of 1993.  The
combined  state and Federal tax  brackets shown reflect the  fact that state tax
payments are currently deductible for Federal  tax purposes. The table does  not
reflect  any local  taxes or  any taxes  other than  personal income  taxes. The
tables illustrate what you  would have to earn  on taxable investments to  equal
the  tax-exempt  estimated  current  return  for  your  income  tax  bracket.  A
taxpayer's marginal tax  rate is  affected by both  his taxable  income and  his
adjusted gross income. Locate your adjusted gross and your taxable income (which
is  your adjusted gross  income reduced by any  deductions and exemptions), then
locate your tax bracket based on joint or single tax filing. Read across to  the
equivalent taxable estimated current return you would need to match the tax-free
income.
 
                                      C-5
<PAGE>
 COMBINED MARGINAL TAX RATES FOR JOINT TAXPAYERS WITH FOUR PERSONAL EXEMPTIONS
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL
    FEDERAL      ADJUSTED      COMBINED
    TAXABLE        GROSS       STATE AND                    TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME        FEDERAL       --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-42.35 $    0-124.50      17.5   %     4.85    5.15    5.45    5.76    6.06    6.36    6.67    6.97
  42.35-102.30      0-124.50      30.0         5.71    6.07    6.43    6.79    7.14    7.50    7.86    8.21
               124.50-186.80      31.0         5.80    6.16    6.52    6.88    7.25    7.61    7.97    8.33
 102.30-155.95      0-124.50      33.0         5.97    6.34    6.72    7.09    7.46    7.84    8.21    8.58
               124.50-186.80      34.0         6.06    6.44    6.82    7.20    7.58    7.95    8.33    8.71
               186.80-309.30      36.5         6.30    6.69    7.09    7.48    7.87    8.27    8.66    9.06
 155.95-278.45 124.50-186.80      39.0         6.56    6.97    7.38    7.79    8.20    8.61    9.02    9.43
               186.80-309.30      42.0         6.90    7.87    8.33    8.50    9.26    9.72   10.19    9.91
                 Over 309.30      39.0   2     6.56    6.97    7.38    7.79    8.20    8.61    9.02    9.43
   Over 278.45 186.80-309.30      46.0         7.41    7.87    8.33    8.80    9.26    9.72   10.19   10.65
                 Over 309.30      42.5   3     6.96    7.39    7.83    8.26    8.70    9.13    9.57   10.00
</TABLE>
 
  COMBINED MARGINAL TAX RATES FOR SINGLE TAXPAYERS WITH ONE PERSONAL EXEMPTION
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                  FEDERAL
    FEDERAL      ADJUSTED      COMBINED
    TAXABLE        GROSS       STATE AND                    TAX-FREE ESTIMATED CURRENT RETURN
    INCOME        INCOME        FEDERAL       --------------------------------------------------------------
   (1,000'S)     (1,000'S)     TAX RATE1      4.00%   4.25%   4.50%   4.75%   5.00%   5.25%   5.50%   5.75%
 ------------- -------------  -----------     ------  ------  ------  ------  ------  ------  ------  ------
 <S>           <C>            <C>             <C>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
 $     0-25.35 $    0-124.50      17.5         4.85    5.15    5.45    5.76    6.06    6.36    6.67    6.97
   25.35-61.40      0-124.50      30.0         5.71    6.07    6.43    6.79    7.14    7.50    7.86    8.21
  61.40-128.10      0-124.50      33.0         5.97    6.34    6.72    7.09    7.46    7.84    8.21    8.58
                124.50-247.0      34.5         6.11    6.49    6.87    7.25    7.63    8.02    8.40    8.78
 128.10-278.45  124.50-247.0      39.5         6.61    7.02    7.44    7.85    8.26    8.68    9.09    9.50
                  Over 247.0      39.0   2     6.56    6.97    7.38    7.79    8.20    8.61    9.02    9.43
   Over 278.45    Over 247.0      42.5   3     6.96    7.39    7.83    8.26    8.70    9.13    9.57   10.00
</TABLE>
 
- ------------------
 
       1 The table reflects the effect of the limitations on itemized deductions
and  the  deduction for  personal exemptions.  They were  designed to  phase out
certain  benefits  of  these  deductions  for  higher  income  taxpayers.  These
limitations,  in effect, raise the current maximum marginal combined tax rate to
approximately 45.77 percent for taxpayers filing a joint return and entitled  to
four personal exemptions and to approximately 42.45 percent for taxpayers filing
a  single return entitled to only  one personal exemption. These limitations are
subject to certain maximums,  which depend on the  number of exemptions  claimed
and  the total  amount of the  taxpayer's itemized deductions.  For example, the
limitation on itemized deductions  will not cause a  taxpayer to lose more  than
80% of his allowable itemized deductions, with certain exceptions.
 
       2  Marginal combined tax rate reverts to  37.79% after the 80% cap on the
limitation on itemized deductions has been met.
 
       3 Marginal combined tax rate reverts to  41.29% after the 80% cap on  the
limitation on itemized deductions has been met.
 
                                      C-6
<PAGE>
STATEMENT OF DIFFERENCES BETWEEN ELECTRONIC FILING AND PRINTED DOCUMENT.
 
   Pursuant  to Rule 499(c) (7) under the  Securities Act of 1933 and Rule 20-11
under the Investment  Company Act  of 1940, Registrant  hereby identifies  those
differences  in the foregoing document between the electronic format in which it
is filed and the printed form in which it will be circulated:
 
   (1)  The printed and distributed prospectus may be paged differently  because
the  printed document may contain a different amount of information on each page
from that contained in the electronic transmission.
 
   (2)  In  the printed  document, footnote symbols  may include  a "dagger"  or
multiple  "dagger". The  "dagger" symbol is  represented as #  in the electronic
document.
 
   (3)  The printed and distributed prospectus will not contain the  preliminary
prospectus legend included at the beginning of the first prospectus page.
<PAGE>
                       CONTENTS OF REGISTRATION STATEMENT
 
A.  BONDING ARRANGEMENTS OF DEPOSITOR:
 
   The  Depositor has obtained the following  Stockbrokers Blanket Bonds for its
officers, directors and employees:
 
<TABLE>
<S>                                                                       <C>
    INSURER/POLICY NO.                                                      AMOUNT
    Reliance Insurance Company                                            $26,000,000
    B 262 6895
</TABLE>
 
B.  THIS AMENDMENT OF REGISTRATION STATEMENT COMPRISES THE FOLLOWING PAPERS AND
DOCUMENTS:
 
                                The facing sheet
 
                           The cross-reference sheet
 
                                 The Prospectus
 
                                 The signatures
 
                         Consents of Independent Public
                      Accountants and Counsel as indicated
 
                         Exhibits as listed on page S-5
 
C.  EXPLANATORY NOTE:
 
   This Amendment  No. 1  to  the Registration  Statement may  contain  multiple
separate  prospectuses.  Each  prospectus  will  relate  to  an  individual unit
investment trust and  will consist  of a  Part A, a  Part B  and an  Information
Supplement.  Each  prospectus  will  be  identical  with  the  exception  of the
respective Part A which will contain the financial information specific to  such
underlying unit investment trust.
 
D.  UNDERTAKINGS:
 
   1.   With  the exception  of the information  included in  the state specific
appendices to the  Information Supplement,  which will vary  depending upon  the
make-up  of a  Fund or  updated to  reflect current  events, any  amendment to a
Fund's Information Supplement will be subject to the review of the staff of  the
Securities and Exchange Commission prior to distribution; and
 
   2.   The  Information Supplement  to the Trust  will not  include third party
financial information.
 
                                      S-1
<PAGE>
                                   SIGNATURES
 
   The Registrant, Nuveen  Tax-Free Unit  Trusts, Series  990 hereby  identifies
Series  401, 507, 512, 515, 517, 519, 723,  814 and 823 of the Nuveen Tax-Exempt
Unit Trust (the former name of the  Nuveen Tax-Free Unit Trust) for purposes  of
the representations required by Rule 487 and represents the following:
 
   (1)    that  the portfolio  securities  deposited  in the  series  as  to the
securities of which  this Registration Statement  is being filed  do not  differ
materially in type or quality from those deposited in such previous series;
 
   (2)   that, except to the extent necessary to identify the specific portfolio
securities deposited in, and to provide essential financial information for, the
series with respect to  the securities of which  this Registration Statement  is
being  filed,  this Registration  Statement  does not  contain  disclosures that
differ in  any  material  respect  from  those  contained  in  the  registration
statements  for  such  previous  series  as  to  which  the  effective  date was
determined by the Commission or the staff; and
 
   (3)  that it has complied with Rule 460 under the Securities Act of 1933.
 
   
   Pursuant to the requirements of the  Securities Act of 1933, the  Registrant,
Nuveen  Tax-Free  Unit Trusts,  Series  990 has  duly  caused this  Amendment of
Registration Statement to be signed on  its behalf by the undersigned  thereunto
duly authorized in the City of Chicago and State of Illinois on March 25, 1998.
    
 
                                          NUVEEN TAX-FREE UNIT TRUST, SERIES 990
                                                             (Registrant)
 
                                          By JOHN NUVEEN & CO. INCORPORATED
                                                             (Depositor)
 
                                          By:  H. William Stabenow
                                          --------------------------------------
                                                             Vice President
 
                                          Attest:  Karen L. Healy
                                          --------------------------------------
                                                             Assistant Secretary
 
                                      S-2
<PAGE>
   Pursuant to the requirements of the Securities Act of 1933, this Amendment of
Registration  Statement has  been signed below  by the following  persons in the
capacities and on the dates indicated:
 
   
<TABLE>
<CAPTION>
          SIGNATURE                        TITLE*                 DATE
<S>                            <C>                              <C>        <C>
Timothy T. Schwertfeger        Chairman, Board of Directors         )
                               Chief Executive Officer and          )
                               Director                             )
                                                                    )
Anthony T. Dean                President, Chief Operating           )
                               Officer and Director                 )           Larry Woods Martin
                                                                    )           Attorney-In-Fact**
                                                                    )
John P. Amboian                Chief Financial Officer and          )             March 25, 1998
                               Executive Vice President             )
                                                                    )
                                                                    )
O. Walter Renfftlen            Vice President and Controller        )
                               (Principal Accounting Officer)       )
                                                                    )
                                                                    )
</TABLE>
    
 
- --------------
 
* The  titles  of the  persons  named herein  represent  their capacity  in  and
relationship to John Nuveen & Co. Incorporated, the Depositor.
 
**  The powers of attorney were filed on Form SE for Messrs. Renfftlen, Dean and
Schwertfeger with the  Amendment to the  Registration Statement on  Form S-6  of
Nuveen  Tax-Free  Unit  Trust, Series  671  (File  No. 33-49175).  The  Power of
Attorney for Messr.  Amboian was filed  with the Amendment  to the  Registration
statement  on  Form S-6  of Nuveen  Tax-Free  Unit Trust,  Series 823  (File No.
33-62325).
 
                                      S-3
<PAGE>
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
    The consent of Arthur Andersen LLP to the use of its name in the  Prospectus
included in the Registration Statement is filed by this amendment as Exhibit 4.4
to the Registration Statement.
 
                         CONSENT OF CHAPMAN AND CUTLER
 
    The  consent of Chapman and Cutler to the  use of its name in the Prospectus
included in the  Registration Statement is  contained in its  opinions filed  by
this amendment as Exhibits 3.1 and 3.2 to the Registration Statement.
 
                            CONSENT OF STATE COUNSEL
 
    The consents of special counsel to the Fund for state tax matters to the use
of  their names  in the  Prospectus included  in the  Registration Statement are
contained in  their opinions  filed by  this  amendment as  Exhibit 3.3  to  the
Registration Statement.
 
                         CONSENT OF STANDARD & POOR'S,
                    A DIVISION OF THE MCGRAW-HILL COMPANIES
 
    The  consent of Standard & Poor's,  a Division of The McGraw-Hill Companies,
to the use of its name in the Prospectus included in the Registration  Statement
is filed by this amendment as Exhibit 4.1 to the Registration Statement.
 
                    CONSENT OF KENNY S&P EVALUATION SERVICES
 
    The  consent of Kenny S&P Evaluation Services to  the use of its name in the
Prospectus included in the Registration Statement is filed by this amendment  as
Exhibit 4.2 to the Registration Statement.
 
                      CONSENT OF CARTER, LEDYARD & MILBURN
 
    The  consent of  Carter, Ledyard  & Milburn to  the use  of its  name in the
Prospectus included in the Registration Statement is filed by this amendment  as
Exhibit 4.3 to the Registration Statement.
 
                                      S-4
<PAGE>
                                LIST OF EXHIBITS
 
<TABLE>
<S>         <C>
1.1(a)      Copy  of Standard Terms and Conditions of Trust between John Nuveen & Co. Incorporated,
            Depositor, and The Chase Manhattan  Bank, Trustee (as Exibit  1.1 (a) to the  Sponsor's
            Registration  Statement  on Form  S-6  relating to  Series 823  of  the Fund  (file No.
            33-62325) and incorporated herein by reference).
1.1(b)      Trust Indenture and Agreement.
2.1         Copy of  Certificate  of  Ownership (Included  in  Exhibit  1.1(a) on  pages  2  to  8,
            inclusive, and incorporated herein by reference).
3.1         Opinion of counsel as to legality of securities being registered.
3.2         Opinion of counsel as to Federal income tax status of securities being registered.
3.3         Opinions  of special state counsel to  the Fund for state tax  matters as to income tax
            status to residents of the respective states of the units of the respective trusts  and
            consents to the use of their names in the Prospectus.
4.1         Consent of Standard & Poor's, a Division of The McGraw-Hill Companies.
4.2         Consent of Kenny S&P Evaluation Services.
4.3         Consent of Carter, Ledyard & Milburn.
4.4         Consent of Arthur Andersen LLP
6.1         List of Directors and Officers of Depositor and other related information (incorporated
            by  reference to Form S-6 [File  No. 33-62325] filed on September  7, 1995 on behalf of
            Nuveen Tax-Free Unit Trust, Series 823).
</TABLE>
 
                                      S-5

<PAGE>
   
EXHIBIT 1.1(B)
NUVEEN TAX-FREE UNIT TRUST, SERIES 990
TRUST INDENTURE AND AGREEMENT
DATED MARCH 25, 1998
    
 
   This  Trust  Indenture  and  Agreement  by  and  between  John  Nuveen  & Co.
Incorporated, as Depositor and The Chase Manhattan Bank, as Trustee, sets  forth
certain provisions in full and incorporates other provisions by reference to the
document  entitled "Standard Terms  and Conditions of  Trust for Nuveen Tax-Free
Unit Trust,  Series 823  and  subsequent Series,  effective September  7,  1995"
(herein  called  the  "Standard  Terms  and  Conditions  of  Trust"),  and  such
provisions as are set forth in full  and such provisions as are incorporated  by
reference  constitute a single instrument. All references herein to Articles and
Sections are to Articles  and Sections of the  Standard Terms and Conditions  of
Trust.
 
                                WITNESSETH THAT:
 
   In  consideration  of  the  promises  and  of  the  mutual  agreements herein
contained, the Depositor and the Trustee, agree as follows:
 
                                     PART I
 
                     STANDARD TERMS AND CONDITIONS OF TRUST
 
   Subject to the Provisions of Part II hereof, all the provisions contained  in
the  Standard Terms and Conditions of Trust are herein incorporated by reference
in their entirety and shall be deemed to  be a part of this instrument as  fully
and  to the same extent as though said  provisions had been set forth in full in
this instrument.
 
                                    PART II
 
                     SPECIAL TERMS AND CONDITIONS OF TRUST
 
   The following special terms and conditions are hereby agreed to:
 
   (a)  The Bonds defined  in Section 1.01(1) listed  in Schedule A hereto  have
been deposited in trust under this Trust Indenture and Agreement.
 
   (b)   The fractional  undivided interest in  and ownership of  the Trust Fund
represented by each  Unit for  a Trust  on the Initial  Date of  Deposit is  the
amount  set  forth  under  the  captions  "Essential  Information  -- Fractional
Undivided Interest in the Trust per Unit" in the Prospectus.
 
   (c)  The  number of  Units created  of a  Trust are  as set  forth under  the
caption  "Essential Information --  Number of Units" in  the Prospectus for each
Trust.
 
   (d)   Notwithstanding anything  to the  contrary in  the Standard  Terms  and
Conditions  of Trust, the phrase "Nuveen  Tax-Exempt Unit Trust" shall be hereby
replaced with the phrase "Nuveen Tax-Free Unit Trust."
<PAGE>
   In Witness Whereof,  John Nuveen &  Co. Incorporated, has  caused this  Trust
Indenture  and  Agreement for  Nuveen  Tax-Free Unit  Trusts,  Series 990  to be
executed by its President, one  of its Vice Presidents  or one of its  Assistant
Vice  Presidents and its corporate seal to be hereto affixed and attested by its
Secretary or its  Assistant Secretary and  The Chase Manhattan  Bank has  caused
this  Trust Indenture and Agreement to be executed by one of its Vice Presidents
or Second  Vice Presidents  and its  corporate  seal to  be hereto  affixed  and
attested  to by one  of its Assistant Treasurers;  all as of  the day, month and
year first above written.
 
John Nuveen & Co. Incorporated,
Depositor
By Anna Kucinskis
Authorized Officer
(Seal)
Attest:
By Karen L. Healy
                   Assistant Secretary
 
The Chase Manhattan Bank, Trustee
By Timothy Kelley
Second Vice President
(Seal)
Attest:
By Joseph Lyons
                   Assistant Treasurer
 
                SCHEDULE A TO THE TRUST INDENTURE AND AGREEMENT
                         SECURITIES INITIALLY DEPOSITED
                                       IN
                    NUVEEN TAX-FREE UNIT TRUSTS, SERIES 990
 
(Note:  Incorporated herein and made a part hereof is the "Schedule of
Investments" as set forth for each Trust in the Prospectus.)

<PAGE>
EXHIBIT 3.1
 
(ON CHAPMAN AND CUTLER LETTERHEAD)
 
   
March 25, 1998
    
 
John Nuveen & Co. Incorporated
333 W. Wacker Drive
Chicago, Illinois 60606
 
RE:  NUVEEN TAX-FREE UNIT TRUST, SERIES 990
 
Gentlemen:
 
   We  have served  as counsel  for you,  as depositor  of Nuveen  Tax-Free Unit
Trusts, Series 990 (hereinafter referred to  as the "Fund"), in connection  with
the  issuance  under the  Trust Indenture  and Agreement  dated the  date hereof
between John Nuveen &  Co. Incorporated, as Depositor,  and The Chase  Manhattan
Bank,  as Trustee, of Units of fractional  undivided interest in the one or more
Trusts of said Fund (hereinafter referred to as the "Units").
 
   In  connection  therewith,  we  have  examined  such  pertinent  records  and
documents  and matters of law as we have  deemed necessary in order to enable us
to express the opinions hereinafter set forth.
 
   Based upon the foregoing, we are of the opinion that:
 
   1.  The execution and delivery of  the Trust Indenture and Agreement and  the
establishment  of  book  entry  positions  and  the  execution  and  issuance of
certificates evidencing  the Units  in the  Trusts of  the Fund  have been  duly
authorized; and
 
   2.   The book  entry positions and  certificates evidencing the  Units in the
Trusts of the Fund when duly established  or duly executed and delivered by  the
Depositor  and the Trustee in accordance with the aforementioned Trust Indenture
and Agreement, will constitute valid and binding obligations of such Trusts  and
the Depositor in accordance with the terms thereof.
 
   We  hereby  consent  to the  filing  of this  opinion  as an  exhibit  to the
Registration Statement (File No.  333-46763) relating to  the Units referred  to
above  and to  the use  of our  name and to  the reference  to our  firm in said
Registration Statement and in the related Prospectus.
 
Respectfully submitted,
 
CHAPMAN AND CUTLER

<PAGE>
                                                                     EXHIBIT 3.2
 
(ON CHAPMAN AND CUTLER LETTERHEAD)
 
March 25, 1998
 
John Nuveen & Co. Incorporated
333 W. Wacker Drive
Chicago, Illinois 60606
 
RE:  Nuveen Tax-Free Unit Trust, Series 990
 
Gentlemen:
 
   We  have served  as counsel  for you,  as Depositor  of Nuveen  Tax-Free Unit
Trust, Series 990 (the "Fund") in  connection with the issuance under the  Trust
Indenture  and  Agreement,  dated the  date  hereof  between John  Nuveen  & Co.
Incorporated, as Depositor, and The Chase  Manhattan Bank, as Trustee, of  Units
of  fractional undivided  interest (the "Units"),  as evidenced by  a book entry
position or certificate, if requested by the  purchaser of Units, in the one  or
more Trusts of said Fund.
 
   We have also served as counsel for you in connection with all previous Series
of  the Nuveen  Tax-Free Unit  Trust and as  such have  previously examined such
pertinent records and documents and matters of law as we have deemed  necessary,
including  (but not limited to) the  Trust Indenture and Agreements with respect
to those series. We have also examined such pertinent records and documents  and
matters  of law as we  have deemed necessary including  (but not limited to) the
Trust Indenture and  Agreement relating  to Nuveen Tax-Free  Unit Trust,  Series
990.
 
   We have concluded that the Trust Indenture and Agreement for the Fund and its
counterpart in each of the prior issues of Nuveen Tax-Free Unit Trust are in all
material  respects  substantially  identical.  For  purposes  of  the  following
opinions, it is assumed that  each asset of the Trust  is debt, the interest  on
which is excluded from gross income for federal income tax purposes.
 
   Based  upon the foregoing, and upon such matters  of law as we consider to be
applicable, we are of the opinion that, under existing federal income law:
 
   (i)  Each of the Trusts will  not be an association taxable as a  corporation
but  will be governed by the provisions  of Subchapter J (relating to Trusts) of
Chapter 1, Internal Revenue Code of 1986 (the "Code").
 
   (ii)  Each Unitholder will be considered  as owning a pro rata share of  each
asset  of the respective Trust of the Fund  in the proportion that the number of
Units of such Trust held by him  bears to the total number of outstanding  Units
of such Trust. Under Subpart E, Subchapter J of Chapter 1 of the Code, income of
each  Trust will  be treated as  income of each  Unitholder of the  Trust in the
proportion described, and an item of  Trust income will have the same  character
in  the hands  of a Unitholder  as it  would have in  the hands  of the Trustee.
Accordingly, to the extent that the income  of a Trust consists of interest  and
original  issue discount excludable  from gross income under  Section 103 of the
Code,  such  income  will  be  excludable  from  Federal  gross  income  of  the
Unitholder,  except in the case of a Unitholder  who is a substantial user (or a
person related to  such user)  of a facility  financed through  issuance of  any
industrial  development  bonds or  certain private  activity  bonds held  by the
Trust. In the case of such Unitholder  who is a substantial user (and no  other)
interest  received with  respect to  his Units  attributable to  such industrial
development bonds or  such private  activity bonds  is includable  in his  gross
income. To the extent the Trust holds bonds that are "specified private activity
bonds"  within the meaning of  Section 57(a)(5) of the  Code, a Unitholder's pro
rata portion of  the income on  such Bonds will  be included as  an item of  tax
preference  in the  computation of  the alternative  minimum tax  applied to all
taxpayers (including non-corporate taxpayers) subject to the alternative minimum
tax. In  the case  of certain  corporations, interest  on all  of the  Bonds  is
included  in computing the alternative minimum tax pursuant to Sections 56(c) of
the Code and  the branch profits  tax imposed by  Section 884 of  the Code  with
respect to U.S. branches of foreign corporations.
 
   (iii)   Gain or  loss will be  recognized to a  Unitholder upon redemption or
sale of his Units. Such  gain or loss is measured  by comparing the proceeds  of
such  redemption or  sale with  the adjusted basis  of the  Units. If  a Bond is
acquired with accrued interest, that portion  of the price paid for the  accrued
interest  is added to the  tax basis of the Bond.  When this accrued interest is
received, it is treated as a return of capital and reduces the tax basis of  the
Bond.  If a Bond is purchased for a  premium, the amount of the premium is added
to the tax basis of the Bond. Bond premium is amortized over the remaining  term
of  the Bond,  and the tax  basis of the  Bond is  reduced each tax  year by the
amount of the premium  amortized in that tax  year. Unitholders must reduce  the
tax  basis of their  Units for their  share of accrued  interest received by the
Trust, if any, on Bonds delivered after  the Unitholders pay for their Units  to
the  extent that such interest  accrued on such Bonds  before the date the Trust
acquired ownership of the Bonds (and the amount of this reduction may exceed the
amount  of  accrued  interest  paid  to  the  seller)  and,  consequently,  such
Unitholders   may   have  an   increase  in   taxable   gain  or   reduction  in
<PAGE>
capital loss upon the disposition of such  Units. Such gain or loss is  measured
by  comparing the proceeds of such redemption or sale with the adjusted basis of
such Units. In addition, such basis  will be increased by both the  Unitholder's
aliquot  share of the  accrued original issue discount  (and market discount, if
the Unitholder elects to include market  discount in income as it accrues)  with
respect  to each Bond held by the Trust with respect to which there was original
issue discount at  the time the  Bond was  issued (or which  was purchased  with
market discount) and reduced by the annual amortization of bond premium, if any,
on Bonds held by the Trust.
 
   (iv)   If the Trustee disposes of a  Trust asset (whether by sale, payment on
maturity, redemption or otherwise), gain or loss is recognized to the Unitholder
and the amount thereof is measured  by comparing the Unitholder's aliquot  share
of  the total proceeds  from the transaction  with his basis  for his fractional
interest in the asset disposed of. Such basis is ascertained by apportioning the
tax basis for his Units among each of the Trust assets (as of the date on  which
his  Units were acquired) ratably according to  their values as of the valuation
date nearest the date on which he purchased such Units. A Unitholder's basis  in
his  Units and of his fractional interest in each Trust asset must be reduced by
the amount of his aliquot  share of accrued interest  received by the Trust,  if
any,  on Bonds delivered after the Unitholders pay for their Units to the extent
that such interest accrued on the  Bonds before the Trust acquired ownership  of
the  Bonds (and the  amount of this  reduction may exceed  the amount of accrued
interest paid to the seller), must be reduced by the annual amortization of bond
premium, if  any, on  Bonds held  by the  Trust; and  must be  increased by  the
Unitholder's  share of accrued original issue  discount (and market discount, if
the Unitholder elects to include market  discount in income as it accrues)  with
respect  to each Bond which, at the time the Bond was issued, had original issue
discount (or which was purchased with market discount).
 
   (v)  In the case of any Bond  held by the Trust where the "stated  redemption
price  at maturity"  exceeds the  "issue price,"  such excess  shall be original
issue discount. With respect to each Unitholder, upon the purchase of his  Units
subsequent  to  the  original  issuance  of  Bonds  held  by  the  Trust Section
1272(a)(7) of the Code provides for  a reduction in the accrued "daily  portion"
of  such original issue discount  upon the purchase of  a Bond subsequent to the
Bond's original issue, under certain circumstances. In the case of any Bond held
by the Trust the interest on which is excludable from gross income under Section
103 of the Code, any original issue discount which accrues with respect  thereto
will  be treated as interest which is excludable from gross income under Section
103 of the Code.
 
   (vi)  In  the case of  Trusts for which  MBIA Insurance Corporation  ("MBIA")
insurance  with respect to each of the Bonds deposited therein has been obtained
by the Depositor or the issuer or underwriter of the Bonds, we have examined the
form of MBIA's policy  or several policies of  insurance (the "Policies")  which
have  been delivered to the Trustee. Assuming issuance of Policies in such form,
in our  opinion, any  amounts  paid under  said Policies  representing  maturing
interest  on defaulted Bonds held by the Trustee will be excludable from Federal
gross income if, and  to the same  extent as, such interest  would have been  so
excludable  if paid in normal course of business by the respective issuer of the
defaulted Bonds, provided  that, at the  time such policies  are purchased,  the
amounts paid for such policies are reasonable, customary and consistent with the
reasonable  expectation that the  issuer of the Bonds,  rather than the insurer,
will pay  debt  service  on  the  Bonds.  Paragraph  (ii)  of  this  opinion  is
accordingly applicable to Policy proceeds representing maturing interest.
 
   (vii)   Certain bonds in the portfolio of  the Trust have been insured by the
issuers, underwriters,  the Sponsor  or  others against  default in  the  prompt
payment  of  principal and  interest (the  "Insured Bonds").  Such Bonds  are so
designated on the portfolio pages in the Prospectus for each Trust. Insurance on
Insured Bonds is effective so long as such Bonds remain outstanding. For each of
these Bonds, we have  been advised that the  aggregate principal amount of  such
Bonds listed on the portfolio page was acquired by the Trust and are part of the
series  of such Bonds in  the listed aggregate principal  amount. Based upon the
assumption that the Insured Bonds of the  Trust are part of a series covered  by
an  insurance policy, it is  our opinion that any  amounts received by the Trust
representing maturing interest  on such  Bonds will be  excludable from  Federal
gross  income if, and  to the same extent  as, such interest  would have been so
excludable if paid in  normal course by  the Issuer provided  that, at the  time
such  policies are purchased, the amounts paid for such policies are reasonable,
customary and consistent with the reasonable expectation that the issuer of  the
Bonds,  rather than the  insurer will pay  debt service on  the Bonds. Paragraph
(ii) of this opinion is accordingly applicable to such payment.
 
   Because the Trusts  do not include  any "private activity  bonds" within  the
meaning  of Section 57(a)(5) of the Code issued on or after August 8, 1986, none
of the  Trust  Fund's  interest income  shall  be  treated as  an  item  of  tax
preference   when  computing  the  alternative  minimum  tax.  In  the  case  of
corporations,  for  taxable  years  beginning  after  December  31,  1986,   the
alternative  minimum tax  and the  Superfund Tax  depend upon  the corporation's
alternative minimum taxable income ("AMTI"), which is the corporation's  taxable
income with certain adjustments.
 
   Pursuant  to Section 56(c) of  the Code, one of  the adjustment items used in
computing AMTI  of  a  corporation  (other  than  an  S  Corporation,  Regulated
Investment Company, Real Estate Investment Trust or
<PAGE>
REMIC)  for tax years beginning in 1989 is  an amount equal to 75% of the excess
of such corporation's "adjusted  current earnings" over an  amount equal to  its
AMTI  (before such  adjustment item and  the alternative tax  net operating loss
deduction).  "Adjusted  current  earnings"  includes  all  tax-exempt  interest,
including  interest on  all Bonds  in the  Trust, and  tax-exempt original issue
discount.
 
   Sections 1288 and 1272 of the Code  provide a complex set of rules  governing
the  accrual of original issue discount. These rules provide that original issue
discount accrues either  on the basis  of a constant  compound interest rate  or
ratably over the term of the Bond, depending on the date the Bond was issued. In
addition,  special  rules apply  if the  purchase  price of  a Bond  exceeds the
original issue price plus the amount of original issue discount which would have
previously accrued based upon its issue price (its "adjusted issue price").  The
application  of these rules will also vary depending on the value of the bond on
the date a Unitholder acquires his Units, and the price the Unitholder pays  for
his Units.
 
   Effective  for tax returns  filed after December 31,  1987, all taxpayers are
required to disclose to  the Internal Revenue Service  the amount of  tax-exempt
interest earned during the year.
 
   Section 265 of the Code provides for a reduction in each taxable year of 100%
of  the otherwise deductible  interest on indebtedness  incurred or continued by
financial institutions, to which either Section  585 or Section 593 of the  Code
applies,  to purchase or  carry obligations acquired after  August 7, 1986 (with
certain exceptions), the interest on which  is exempt from Federal income  taxes
for  such taxable  year. Under  rules prescribed by  Section 265,  the amount of
interest otherwise deductible by such financial institutions in any taxable year
which is  deemed to  be attributable  to tax-exempt  obligations acquired  after
August  7, 1986, will generally  be the amount that bears  the same ratio to the
interest deduction  otherwise allowable  (determined without  regard to  Section
265)  to the taxpayer  for the taxable  year as the  taxpayer's average adjusted
basis (within the meaning  of Section 1016)  of tax-exempt obligations  acquired
after August 7, 1986, bears to such average adjusted basis for all assets of the
taxpayer.  The  U.S. Treasury  Department has  proposed extending  the financial
institution rules to all corporations.
 
   We also call  attention to  the fact  that, under  Section 265  of the  Code,
interest on indebtedness incurred or continued to purchase or carry Units is not
deductible  for Federal  income tax purposes.  Under rules used  by the Internal
Revenue Service for determining when borrowed funds are considered used for  the
purpose  of purchasing or carrying particular  assets, the purchase of Units may
be considered to  have been made  with borrowed funds  even though the  borrowed
funds  are not directly traceable to the purchase of Units. However, these rules
generally  do  not  apply  to   interest  paid  on  indebtedness  incurred   for
expenditures  of a personal  nature such as  a mortgage incurred  to purchase or
improve a personal residence.
 
   "The Revenue Reconciliation Act of 1993" (the "Tax Act") subjects  tax-exempt
bonds  to the market  discount rules of  the Code effective  for bonds purchased
after April 30,  1993. In general,  market discount  is the amount  (if any)  by
which  the stated  redemption price at  maturity exceeds  an investor's purchase
price (except to  the extent that  such difference, if  any, is attributable  to
original issue discount not yet accrued) subject to a statutory de minimis rule.
Market discount can arise based on the price a Trust pays for Bonds or the price
a  Unitholder pays for his or her Units.  Under the Tax Act, accretion of market
discount is taxable as ordinary income; under prior law, the accretion had  been
treated  as capital gain.  Market discount that  accretes while a  Trust holds a
Bond would be recognized  as ordinary income by  the Unitholders when  principal
payments  are received on the Bond, upon  sale or at redemption (including early
redemption), or  upon the  sale or  redemption of  his or  her Units,  unless  a
Unitholder elects to include market discount in taxable income as it accrues.
 
   We  have not examined any of the Bonds  to be deposited and held in the Trust
or the proceedings for the issuance thereof or the opinions of bond counsel with
respect thereto, and therefore express no opinion as to the exemption from State
income taxes of interest on the Bonds if received directly by a Unitholder.
 
   We hereby  consent  to the  filing  of this  opinion  as an  exhibit  to  the
Registration  Statement (File No.  333-46763) relating to  the Units referred to
above and to  the use  of our  name and to  the reference  to our  firm in  said
Registration Statement and in the related Prospectus.
 
Respectfully submitted,
 
CHAPMAN AND CUTLER

<PAGE>
EXHIBIT 3.3
 
(ON EDWARDS & ANGELL LETTERHEAD)
 
   
MARCH 25, 1998
    
 
   
Nuveen Tax-Free Unit Trust, Series 990
In care of John Nuveen & Co. Incorporated
333 West Wacker Drive
Chicago, IL 60606
    
 
Attention of Gifford R. Zimmerman, Esq.
Vice President, General Counsel
and Secretary
 
   
The Chase Manhattan Bank,
as Trustee of Nuveen Tax-Free Unit Trust, Series 990
Nuveen Administration Department
4 New York Plaza-Third Floor
New York, New York 10004-2413
    
 
Re:  Massachusetts Insured Trust 152
 
Dear Sirs:
 
   
    We  have acted as  special counsel, with respect  to Massachusetts State and
local tax matters, to the above  mentioned Trust(s) ("Trust(s)") of Nuveen  Tax-
Free  Unit Trust,  Series 990 (the  "Fund") concerning  a Registration Statement
(No. 333-46763) on Form S-6  under the Securities Act  of 1933, as amended  (the
"Registration  Statement"),  covering  the  issuance by  the  Fund  of  Units of
fractional undivided interest in the Fund.
    
 
    We have not been furnished with a copy of the Registration Statement or  the
prospectus,  which  is a  part of  the Registration  Statement, relating  to the
issuance by the Fund of the Units.  However, John Nuveen & Co. Incorporated  has
authorized  us to assume that  the proposed offer and sale  of the Units will be
carried out in that same manner and  upon the same terms and conditions as  that
described  in the prospectus for the Nuveen Tax-Exempt Unit Trust, Series 351 --
Massachusetts Trust 182, dated November 6, 1985.
 
    We have been furnished with a copy  of the opinion of Chapman and Cutler  on
the   federal  tax  status  of  the  Fund,  its  constituent  Trusts  and  their
Unitholders.
 
    In addition, we have also examined applicable Massachusetts law and a ruling
of the Massachusetts Department of Revenue  dated February 7, 1985, relating  to
Multi-State Series 162.
 
    Based  on  the foregoing  it  is our  opinion  that under  existing  law and
administration of the affairs of the Trust(s):
 
    A.--For Massachusetts income tax purposes, each  Trust will be treated as  a
corporate  trust under Section 8 of Chapter 62 of the Massachusetts General Laws
("M.G.L.") and not as a grantor trust under Section 10(e) of M.G.L. Chapter 62.
 
    B.--The  Trust(s)  will  not  be  held   to  be  engaging  in  business   in
Massachusetts  within the meaning of said Section  8 and will, therefore, not be
subject to Massachusetts income tax.
 
    C.--Unitholders who  are  subject  to Massachusetts  income  taxation  under
M.G.L. Chapter 62 will not be required to include their respective shares of the
earnings  of or  distributions from  the Trust(s)  in their  Massachusetts gross
income to the extent  that such earnings  or distributions represent  tax-exempt
interest  excludable from gross income for  federal income tax purposes received
by  the  Trust(s)  on  obligations   issued  by  Massachusetts,  its   counties,
municipalities,  authorities, political subdivisions  or instrumentalities or by
Puerto Rico, the  Virgin Islands, Guam,  the Northern Mariana  Islands or  other
possessions  of the United  States within the  meaning of Section  103(c) of the
Internal Revenue Code of 1986, as amended ("Obligations").
 
    D.--In the  case  of a  Massachusetts  Insured Trust,  Unitholders  who  are
subject  to Massachusetts  income taxation under  M.G.L. Chapter 62  will not be
required to include their respective shares of the earnings of or  distributions
from  such Trust  in their  Massachsetts gross  income to  the extent  that such
earnings or distributions are derived from the proceeds of insurance obtained by
the Sponsor of such Trust or by the issuer or underwriter of an obligation  held
by  such Trust that represent maturing interest on defaulted obligations held by
the Trustee, if and to the same extent that such earnings or distributions would
have been excludable from the gross  income of such Unitholders if derived  from
interest paid by the issuer of the defaulted obligation.
<PAGE>
    E.--Unitholders  which  are corporations  subject  to taxation  under M.G.L.
Chapter 63 will be required to  include their respective shares of the  earnings
of or distributions from the Trust(s) in their Massachusetts gross income to the
extent  that such earnings or distributions represent interest from bonds, notes
or indebtedness of any state, including Massachusetts, except for interest which
is specifically exempted from such tax by the acts authorizing issuance of  said
Obligations.
 
    F.--Each Trust's capital gains and/or capital losses which are includable in
the  federal gross income of Unitholders who are subject to Massachusetts income
taxation under M.G.L. Chapter 62, or Unitholders which are corporations  subject
to  Massachusetts taxation under  M.G.L. Chapter 63 will  be included as capital
gains and/or losses in the  Unitholders' Massachusetts gross income, except  for
capital gain which is specifically exempted from taxation under such Chapters by
the acts authorizing issuance of said Obligations.
 
    G.--Unitholders  which are corporations subject  to tax under M.G.L. Chapter
63 and which are tangible property corporations will not be required to  include
the   Units  when  determining  the  value  of  their  tangible  property;  such
Unitholders which  are  intangible property  corporations  will be  required  to
include the Units when determining their net worth.
 
    H.--Gains or losses realized on sales or redemptions of Units by Unitholders
who  are subject  to Massachusetts  income taxation  under M.G.L.  Chapter 62 or
Unitholders which  are  corporations  subject to  Massachusetts  taxation  under
M.G.L.  Chapter 63  will be includable  in their Massachusetts  gross income. In
determining such gain or loss Unitholders will, to the same extent required  for
Federal tax purposes, have to adjust their tax bases for their Units for accrued
interest  received, if  any, on Obligations  delivered to the  Trustee after the
Unitholders pay  for their  Units,  for amortization  of  premiums, if  any,  on
Obligations  held by the Trust(s), and  for accrued original issue discount with
respect to each  Obligation which, at  the time the  Obligation was issued,  had
original issue discount.
 
    I.--The  Units of the Trust(s) are not subject to any property tax levied by
Massachusetts or any political subdivision thereof, nor to any income tax levied
by any such political subdivision. They are includable in the gross estate of  a
deceased  Unitholder  who is  a resident  of Massachusetts  for purposes  of the
Massachusetts Estate Tax.
 
    The foregoing  opinions are  based upon  present provisions  of federal  and
Massachusetts  law, administrative interpretations  thereof and court decisions.
With respect  to Unitholders  which are  corporations subject  to  Massachusetts
taxation under M.G.L. Chapter 63, no opinion is rendered on the includability of
their respective shares of the earnings of or distributions from the Trust(s) in
their   Massachusetts  gross  income  to  the   extent  that  such  earnings  or
distributions represent interest  from bonds, notes,  or indebtedness of  Puerto
Rico,   the  Virgin  Islands,  Guam,  the  Northern  Mariana  Islands  or  other
possessions of the  United States within  the meaning of  Section 103(c) of  the
Internal Revenue Code of 1986, as amended.
 
    We  hereby  consent to  the  filing of  this opinion  as  an exhibit  to the
Registration Statement and  to the reference  to our firm  in such  Registration
Statement and the Prospectus included therein.
 
Very truly yours,
 
EDWARDS & ANGELL

<PAGE>
EXHIBIT 3.3
 
(ON EDWARDS & ANGELL LETTERHEAD)
 
   
MARCH 25, 1998
    
 
   
Nuveen Tax-Free Unit Trust,
Series 990
In care of John Nuveen & Co. Incorporated
333 West Wacker Drive
Chicago, IL 60606
    
 
Attention of Gifford R. Zimmerman
Vice President, Assistant General Counsel
and Assistant Secretary
 
   
The Chase Manhattan Bank,
as Trustee of Nuveen Tax-Free Unit Trust,
Series 990
4 New York Plaza, 3rd Floor
New York, NY 10004-2413
    
 
Re:--New York Insured Trust 278
 
Dear Sirs:
 
   
    We  have acted as  special counsel, with  respect to New  York State and New
York City tax matters,  to the above Trusts(s)  ("New York Trust(s)") of  Nuveen
Tax-Free Unit Trust, Series 990 (the "Fund") concerning a Registration Statement
(No.  333-46763) on Form S-6  under the Securities Act  of 1933, as amended (the
"Registration Statement"), covering the  issuance by the  New York Trusts(s)  of
units of fractional undivided interest in the New York Trust(s)( "Units").
    
 
    We  have not been furnished with a copy of the Registration Statement or the
prospectus, which  is a  part of  the Registration  Statement, relating  to  the
issuance  by the  New York  Trust(s) of  the Units.  However, John  Nuveen & Co.
Incorporated has authorized us to assume that the proposed offer and sale of the
Units will  be carried  out in  that same  manner and  upon the  same terms  and
conditions  as that described in  the prospectus for the  Nuveen Tax Exempt Unit
Trust, Insured Series 193, dated May 19,  1989, which we were furnished and  did
examine.  In the case of a  Fund which contains a New  York Insured Trust or New
York Intermediate  Insured  Trust, we  also  were not  furnished  the  Insurance
Agreement   (the  "Policy")  between  the  Municipal  Bond  Investors  Assurance
Corporation (the "Insurer"), the Depositor and the Trustee. However, John Nuveen
& Co.  Incorporated  has  authorized  us  to assume  that  the  Policy  will  be
implemented  at the closing of the Trust and be in substance and form materially
similiar to the Policy applicable to New  York Insured Trust 108, which we  were
furnished and did examine.
 
    We have not been furnished with a copy of the Opinion of Chapman & Cutler on
the   Federal  Tax  status  of  the  Fund,  its  constituent  Trusts  and  their
Unitholders. However, John Nuveen & Co. Incorporated has authorized us to assume
that such Opinion will be in substance and form materially similar to that which
was issued in connection with Nuveen  Tax Exempt Unit Trust, Insured Series  193
dated May 19, 1989, which we were furnished and did examine.
 
    Based on the foregoing, we are of the opinion that, for purposes of New York
State and New York City franchise taxes, a New York Trust will be a trust not an
association  taxable as  a corporation;  the proposed  activities of  a New York
Trust will not constitute doing business within the meaning of section 208.1  of
the New York Tax Law or section R46-3.0 of the N.Y.C. Administrative Code; a New
York  Trust will not be subject to New York State or New York City franchise tax
imposed on business corporations; a  New York Trust will  not be subject to  the
unincorporated  business income tax imposed by Article 23 of the N.Y. Tax Law or
Chapter 46, Title S of the N.Y.C.  Administrative Code; and the income of a  New
York Trust will be treated as income of the Unitholders.
 
    We  are further of the opinion  that, under existing laws and administration
of the affairs of the New York Trust(s):
 
    (A)--Interest  on  obligations  issued  by  New  York  State,  a   political
subdivision thereof, Puerto Rico, the Virgin Islands, Guam, the Northern Mariana
Islands, or other possessions of the United States within the meaning of Section
103(c)  of the Internal Revenue Code  of 1986, as amended, ("Obligations") which
would be exempt  from New York  State or New  York City personal  income tax  if
directly received by a Unitholder, will retain its status as tax-exempt interest
when received by a New York Trust and distributed to such Unitholder;
 
    (B)--Interest  (less amortizable  premium, if any)  derived from  a New York
Trust by a Unitholder who is a resident of New York State (or New York City)  in
respect  of Obligations issued by states other than New York (or their political
subdivisions) will be  subject to  New York State  (or New  York City)  personal
income tax;
<PAGE>
    (C)--A  Unitholder who is  a resident of  New York State  (or New York City)
will be subject to New  York State (or New York  City) personal income tax  with
respect  to gains realized when Obligations  held in the Unitholder's respective
New York Trust are sold, redeemed or  paid at maturity or when the  Unitholder's
Units  are  sold  or  redeemed;  such gain  will  equal  the  proceeds  of sale,
redemption or payment less the tax basis of the Obligation or Unit (adjusted  to
reflect (a) the amortization of premium or discount (if any) on Obligations held
by  the New York Trust, (b) accrued original issue discount with respect to each
Obligation which, at  the time  the Obligation  was issued,  had original  issue
discount,  and (c) the deposit  of Obligations with accrued  interest in the New
York Trust after the Unitholder's settlement date);
 
    (D)--Interest or gain from a New York  Trust derived by a Unitholder who  is
not  a resident of New York State (or New  York City) will not be subject to New
York State (or New York City) personal income tax, unless the Units are property
employed in a business, trade, profession  or occupation carried on in New  York
State (or New York City);
 
    (E)--In  the  case of  a New  York  Insured Trust  or New  York Intermediate
Insured Trust, amounts paid under the Policies representing maturing interest on
defaulted Obligations held by the Trustee  in the Trust will be excludable  from
New  York State and  New York City  income if, and  to the same  extent as, such
interest would have been excludable if paid by the respective issuer; and
 
    (F)--Amounts distributable from a  New York Trust which  are, pursuant to  a
Unitholder's  election, automatically reinvested in  Nuveen Municipal Bond Fund,
Inc. will  be treated  as if  actually  distributed to  and reinvested  by  such
Unitholder.
 
    Because  of the requirement that tax cost  basis be adjusted as discussed in
(C) above, under some circumstances a  Unitholder may realize taxable gain  when
his  Units are sold or redeemed for an amount equal to or less than his original
cost.
 
    Although interest  on  Obligations  issued  by  New  York  (or  a  political
subdivision  thereof) would generally be exempt from New York State and New York
City tax, a special limitation may apply with respect to private activity  bonds
which  are not qualified  bonds within the  meaning of section  103(b)(1) of the
Internal Revenue Code of 1986,  as amended. The interest  on such bonds, to  the
extent  received by a Unitholder who is  a "substantial user" (or person related
to such user) of the facilities financed by such bonds, will not be exempt  from
New  York State and New York City tax for any period during which such bonds are
beneficially held by such "substantial user" or "related person".
 
    As an additional matter, if borrowed funds  are used to purchase Units in  a
New  York Trust, all (or part) of the  interest on such indebtedness will not be
deductible for New York State  and New York City  tax purposes. The purchase  of
Units  may be considered to have been  made with borrowed funds even though such
funds are not directly traceable to the purchase of Units in any New York Trust.
 
    We are further of the opinion that,  for purposes of the New York State  and
New  York City franchise  tax on corporations, Unitholders  which are subject to
such tax will be required to include in their entire net income any interest  or
gains  distributed to them in  respect of obligations of  any state or political
subdivision  thereof,  including  New  York.  No  opinion  is  rendered  on  the
includability  in entire net income of  interest distributed to such Unitholders
in respect of obligations issued by  Puerto Rico, the Virgin Islands, Guam,  the
Northern  Mariana Islands or  other possessions of the  United States within the
meaning of Section 103(c) of the Internal Revenue Code of 1986, as amended.
 
    The foregoing opinions  are based  upon present provisions  of Federal,  New
York  State and  New York City  law, administrative  interpretations thereof and
court decisions.
 
    In  connection  with  this  offering,  we  have  not  examined  any  of  the
obligations  to be deposited  in the New  York Trust(s), and  express no opinion
whether the interest on any such  obligations is, in fact, exempt from  Federal,
New York State, or New York City income taxation, or that such interest would be
tax-exempt  under Federal,  New York  State, or  New York  City law  if directly
received by  a  Unitholder, nor  have  we made  any  review of  the  proceedings
relating to the issuance of any such obligations.
 
    We  hereby  consent to  the  filing of  this opinion  as  an exhibit  to the
Registration Statement and  to the reference  to our firm  in such  Registration
Statement and the Prospectus included therein.
 
Very truly yours,
 
EDWARDS & ANGELL

<PAGE>
EXHIBIT 3.3
 
(ON DECHERT PRICE & RHOADS LETTERHEAD)
 
   
MARCH 25, 1998
    
 
John Nuveen & Co. Incorporated
333 W. Wacker Drive
Chicago, Illinois 60606
 
   
RE:  Nuveen Tax-Free Unit Trust, Series 990
    Pennsylvania Insured Trust 234
    
 
Gentlemen:
 
   
    You  have requested our  opinion as to  the Pennsylvania tax  aspects of the
above-captioned Trust(s) (the "Pennsylvania Trust(s)") which is (are) a part  of
the  Nuveen Tax-Free Unit Trust Series 990 ("Fund"). The Fund is organized under
the Trust  Indenture and  Agreement, of  even date,  between John  Nuveen &  Co.
Incorporated,  as Depositor, and The Chase  Manhattan Bank, as Trustee. The Fund
will contain several  trusts, including  the Pennsylvania  Trust(s), which  will
issue  Units of fractional  undivided interests. The Units  will be purchased by
various investors  ("Unit  Holder").  Each Unit  of  the  Pennsylvania  Trust(s)
represents  a fractional undivided  interest in the principal  and net income of
such Trust(s)  in the  ratio  of ten  Units  for each  $1,000  of value  of  the
obligations initially acquired by such Trust(s). Each Pennsylvania Trust will be
administered  as  a  distinct entity  with  separate  certificates, investments,
expenses, books and records.
    
 
    The proceeds  of  the  sale of  the  Units  will be  invested  primarily  in
interest-bearing  obligations  issued by  or on  behalf  of the  Commonwealth of
Pennsylvania, its  agencies  and instrumentalities,  or  political  subdivisions
thereof,  including any county,  city, borough, town,  township, school disrict,
municipality, and  local housing  or parking  authority in  the Commonwealth  of
Pennsylvania  or issued by Puerto Rico, the Virgin Islands, Guam or the Northern
Mariana Islands ("Bonds"). Distributions of  the interest received by the  Trust
will  be  made semi-annually  unless the  Unit Holder  elects otherwise.  In the
opinion of bond counsel to each issuer,  the interest on all bonds in the  Trust
is exempt fromn federal income tax under existing law.
 
    You  have advised us that for  federal income tax purposes each Pennsylvania
Trust will  not  be taxable  as  an association  but  will be  governed  by  the
provisions  of Subchapter J  (relating to Trusts)  of Chapter 1  of the Internal
Revenue Code of 1986.  Each Unit Holder  will be considered the  owner of a  pro
rata  portion of  the Unit  Holder's respective  Pennsylvania Trust  and will be
subject to tax  on the income  therefrom under  the provisions of  Subpart E  of
Subchapter  J of Chapter 1 of the  Internal Revenue Code of 1986. A Pennsylvania
Trust itself will not be subject to federal income taxes. For federal income tax
purposes, each item of trust income will have the same character in the hands of
a Unit Holder as it would have in the hands of the Trustee. Accordingly, to  the
extent  that the income of a  Pennsylvania Trust consists of interest excludable
from gross income under Section 103 of  the Internal Revenue Code of 1986,  such
income will be excludable from federal gross income of the Unit Holder.
 
    Based  upon the above facts,  it is our opinion  that for Pennsylvania state
and local tax purposes, a Pennsylvania Trust  will be recognized as a trust  not
taxable as a corporation. It will, therefore, not be subject to the Pennsylvania
Capital  Stock/Franchise Tax or the Pennsylvania Corporate Net Income Tax. Since
all of the income of  a Trust is either  itself income exempt from  Pennsylvania
Personal  Income Tax,  as described below,  or is  required by the  terms of the
Trust to be distributed to the holders  of Units, a Trust should not be  subject
to Pennsylvania Personal Income Tax. The Philadelphia School District Investment
Income Tax described below, is not imposed on trusts.
 
    Various personal property taxes are in effect in Pennsylvania, however, each
of  them exempts, inter alia, Bonds, cash,  checking and savings accounts in and
certificates of  deposit issued  by commercial  banks, savings  institutions  or
trust  companies and United States Treasury obligations. In general, these taxes
apply to a specified  list of items of  intangible personal property  including,
inter  alia, mortgages and  other evidences of indebtedness  and shares of stock
issued by business corporations  not doing business  in Pennsylvania. The  taxes
referred  to above include the County Personal Property Tax imposed on residents
of Pennsylvania  by  the  Act of  June  17,  1913, P.L.  507,  as  amended,  the
additional personal property taxes imposed on Pittsburgh residents by the School
District of Pittsburgh under the Act of June 20, 1947, P.L. 733, as amended, and
by  the City of Pittsburgh by Ordinance No.  599 of December 28, 1967, under the
Act of December 31, 1965, P.L. 1257, and any additional personal property  taxes
that  the School District of Philadelphia may reimpose on Philadelphia residents
under the authority contained in the Act of May 23, 1949, P.L. 1676, as amended.
Units evidencing fractional undivided interests in a Pennsylvania Trust will not
be subject  to any  of  these personal  property taxes  to  the extent  of  that
proportion of a Pennsylvania Trust represented by Bonds and other exempt assets.
Only that
<PAGE>
proportion  of the Units  represented by taxable  assets will be  subject to the
personal property  taxes. Pennsylvania  Trust  Units may  be taxable  under  the
Pennsylvania inheritance and estate taxes.
 
    The  interest  and  gain  from obligations  issued  by  the  Commonwealth of
Pennsylvania or by  its political  subdivisions or  by any  public authority  of
either  are exempt from tax under the Act  of August 31, 1971, P.L. 395, Act No.
94. However, that Act was repealed by the Act of December 3, 1993, P.L. 473, Act
No. 68  ("Act 68  of  1993") with  respect to  obligations  issued on  or  after
February  1, 1994. Pursuant to Act 68  of 1993, profits, gains or income derived
from the sale, exchange  or other disposition  of exempt government  obligations
issued  after  February 1,  1994  will be  subject  to state  or  local taxation
although interest and "income" derived from the exempt obligations will continue
to be exempt  from all state  and local taxation.  Therefore, the proportion  of
income  representing interest  from Bonds distributable  to Unit  Holders is not
taxable under the Pennsylvania Personal Income Tax imposed by Article III of the
Pennsylvania "Tax Reform  Code of 1971",  as amended  by the Act  of August  31,
1971,  P.L. 362, Act  No. 93, or under  the Corporate Net  Income Tax imposed on
corporations by Article IV of the Tax Reform Code. Similarly, such interest will
not be  taxable under  the Philadelphia  School District  Investment Income  Tax
imposed  on Philadelphia resident individuals under  the authority of the Act of
August 9, 1963, P.L. 640, as implemented by Section 19-1804 of the  Philadelphia
Code,  as  amended, and  resolutions of  the  Board of  Education of  the School
District of Philadelphia made pursuant to the ordinances, and such interest will
not be subject to  any of the  taxes on net income  from business activities  in
Philadelphia  under Philadelphia Code  Sections 19-1500 and  19-2600, imposing a
Net Profits Tax and a Business  Privilege Tax respectively. The City and  School
District of Pittsburgh do not impose any taxes on unearned income.
 
    Under  the  Pennsylvania Personal  Income Tax  Law,  personal income  tax is
imposed upon the  following specified  classes of income:  (1) compensation  for
services, (2) net profits from the operation of a business, profession, or other
activity,  (3) net  gains or  income from the  disposition of  property, (4) net
gains or income in the form of rents and royalties, (5) dividends, (6)  interest
from  obligations not otherwise  exempt, (7) gambling  and lottery winnings, (8)
net gains or income from estates or trusts which fall under any of the preceding
classifications. Although there is no published authority on the question, it is
our opinion that any  insurance proceeds paid in  lieu of interest on  defaulted
tax-exempt  obligations  will be  exempt from  Pennsylvania Personal  Income Tax
either as payment  in lieu of  tax-exempt interest or  as payments of  insurance
proceeds  which are not  included in any  of the classes  of income specified as
taxable under  the  Pennsylvania Personal  Income  Tax Law.  Since  Pennsylvania
Corporate  Net  Income Tax  is  imposed upon  the  corporation's net  income for
federal income tax purposes,  because such insurance  proceeds will be  excluded
from  the federal  income tax  base, such  proceeds will  not be  subject to the
Pennsylvania Corporate Net  Income Tax. Finally,  since proceeds from  insurance
policies are expressly excluded from the Philadelphia School District Investment
Income  Tax, insurance  proceeds paid  to replace  defaulted payments  under any
Bonds held by the Pennsylvania Trust(s) will not be subject to this tax.
 
    Under Act 68 of 1993,  a Unit Holder's share of  gain upon disposition of  a
Bond  issued on or after February 1,  1994 by the Pennsylvania Trust, whether by
sale, exchange, redemption  or payment at  maturity, will be  taxable under  the
Pennsylvania  Personal  Income Tax.  Gains on  the  disposition of  Bonds issued
before February  1,  1994  will continue  to  be  exempt. See  72  P.S.  Section
7303(a)(3)  and 61  Pa. Code Section.  121.9(b)(3). While there  is no published
authority with  respect to  the treatment  of  such gains  for purposes  of  the
Philadelphia School District Investment Income Tax, it is our opinion that gains
upon  dispositions of Bonds issued before February  1, 1994 are exempt from this
tax under Act of  August 31, 1971, P.L.  395, Act No. 94,  and, if the  question
were litigated, the Pennsylvania courts should so hold. Gains on the disposition
of  Bonds issued on or after February 1, 1994 will be taxable. In any event, the
Philadelphia School District  Investment Income  Tax has no  application to  any
gain on the disposition of property held for more than six months.
 
    In  C.C. Collings & Co., Inc. v. Commonwealth of Pennsylvania, 514 A.2d 1373
(1986), and two related cases, the Supreme Court of Pennsylvania held that gains
or losses from the sale of obligations of the Commonwealth of Pennsylvania,  its
political  subdivisions, instrumentalities and  agencies are not  subject to the
Corporate Net  Income Tax.  Profits,  gains or  income  derived from  the  sale,
exchange  or other  disposition of those  exempt obligations issued  on or after
February 1, 1994, however, will be subject to tax pursuant to Act 68 of 1993.
 
    There is no  published authority  under any  of the  Pennsylvania state  and
local  income taxes described above with respect  to gain from the redemption or
sale of a Unit. To the extent that such gain represents the Unit Holder's  share
of  any unrealized gain on the Bonds issued  before February 1, 1994 and held by
the Trust, it is our opinion that  such gain is exempt from the  above-described
Pennsylvania  state and local income taxes  and, if the question were litigated,
the Pennsylvania  courts  should  so hold.  To  the  extent that  such  gain  is
attributable  to unrealized gain on  Bonds issued on or  after February 1, 1994,
such gain  will be  taxable under  such taxes.  In any  event, the  Philadelphia
School  District Investment  Income Tax  has no application  to any  gain on the
disposition of property held for more than six months.
 
    Interest on obligations  of Puerto Rico,  the Virgin Islands,  Guam, or  the
Northern  Mariana Islands is, under federal  law, exempt from taxation by states
and municipalities. Federal law  does not expressly  exclude from taxation  gain
realized  upon the disposition of such  obligations. Therefore, a disposition of
such obligations by a Pennsylvania  Trust could be a  taxable event to a  Holder
under  each of the  Pennsylvania state and  local income taxes  discussed in the
preceding paragraphs.  See  Willcuts v.  Bunn,  282  U.S. 216  (1931);  U.S.  v.
Stewart,   311   U.S.   60  (1940).   Similarly,   to  the   extent   that  gain
<PAGE>
on the  redemption  or  sale  of  a Unit  represents  unrealized  gain  on  such
obligations held by a Pennsylvania Trust, such gain could be taxable.
 
   
    We  hereby  consent to  the  filing of  this opinion  as  an exhibit  to the
Registration Statement (No. 333-46763) relating to the Units referred to  above,
and  to the reference  to our firm  as special Pennsylvania  tax counsel in said
Registration Statement and in the related Prospectus.
    
 
Very truly yours,
 
DECHERT PRICE & RHOADS

<PAGE>
EXHIBIT 4.1
 
(ON STANDARD & POOR'S, A DIVISION OF THE MCGRAW-HILL COMPANIES LETTERHEAD)
 
March 25, 1998
 
John Nuveen & Co. Incorporated
333 W. Wacker Drive
Chicago, IL 60606
 
RE:  NUVEEN TAX-FREE UNIT TRUST, SERIES 990
 
Gentlemen:
 
   This  is in response to your request regarding the above-captioned fund which
consists of separate underlying unit investment trusts (the "Trusts"), SEC  file
# 333-46763.
 
   We  have reviewed the information  presented to us and  have assigned a "AAA"
rating to the units of each insured  trust and a "AAA" rating to the  securities
contained  in  each insured  Trust. The  ratings are  direct reflections  of the
portfolio of each  insured trust, which  will be composed  solely of  securities
covered by bond insurance policies that insure against default in the payment of
principal  and interest on the securities contained in each insured trust for as
long as they remain outstanding. We  understand that the bonds described in  the
prospectus  are the same as those in the attached list. Since such policies have
been issued by MBIA which has been assigned a 'AAA' claims paying ability rating
by S&P, S&P has assigned a "AAA" rating to the units of each insured trust and a
"AAA" rating to the securities contained in each insured trust.
 
   Standard &  Poor's  will maintain  surveillance  on the  "AAA"  rating  until
thirteen  months from the initial Date of  Deposit. On this date the rating will
be automatically withdrawn by Standard &  Poor's unless a post effective  letter
is requested by the trust.
 
   You  have permission to use the name of  Standard & Poor's, a Division of The
McGraw-Hill Companies  and the  above-assigned rating  in connection  with  your
dissemination  of information relating to the insured trusts provided that it is
understood that the ratings are not "market" ratings nor recommendations to buy,
hold or sell the units of the insured trusts or the securities contained in  the
insured trusts. Further, it should be understood the rating on the units of each
insured  trust  does not  take  into account  the  extent to  which  the trust's
expenses or portfolio asset sales for less than the trust's purchase price  will
reduce  payment to the unit holders of the interest and principal required to be
paid on the portfolio assets. S&P reserves the right to advise its own  clients,
subscribers,  and the public of  the ratings. S&P relies  on the sponsor and its
counsel, accountants, and other experts for the accuracy and completeness of the
information submitted in connection with the ratings. S&P does not independently
verify the truth or accuracy of any such information.
 
   This letter  evidences our  consent to  the use  of the  name of  Standard  &
Poor's,  a Division of  The McGraw-Hill Companies in  connection with the rating
assigned to the  units of each  insured trust in  the registration statement  or
prospectus relating to the units and the trusts. However, this letter should not
be  construed  as a  consent  by us,  within  the meaning  of  Section 7  of the
Securities Act of 1933, to the use of the name of Standard & Poor's, a  Division
of  The McGraw-Hill  Companies in  connection with  the ratings  assigned to the
securities contained in the insured trusts. You are hereby authorized to file  a
copy of this letter with the Securities and Exchange Commission.
 
   Please be certain to send us three copies of your final prospectus as soon as
it  becomes available. Should we not receive  them within a reasonable amount of
time after the closing or should they not conform to the certification  received
by us, we reserve the right to nullify the ratings.
 
Very truly yours,
 
STANDARD & POOR'S, A DIVISION OF THE MCGRAW-HILL COMPANIES
 
By Sanford Bragg

<PAGE>
                                                                     EXHIBIT 4.2
 
(On J. J. Kenny Co., Inc. Letterhead)
 
   
March 25, 1998
    
 
John Nuveen & Company
333 West Wacker Drive
Chicago, IL 60606
 
Re:  Nuveen Tax-Free Unit Trusts, Series 990
 
Gentlemen:
 
   We  have  examined  the registration  statement  File No.  333-46763  for the
above-captioned trust. We hereby acknowledge that Kenny S&P Evaluation Services,
a division of J. J. Kenny Co., Inc. is currently acting as the evaluator for the
trust. We  hereby  consent to  the  use in  the  Registration Statement  of  the
reference  to Kenny S&P Evaluation Services, a division of J. J. Kenny Co., Inc.
as evaluator.
 
   In addition, we hereby confirm that the ratings indicated in the Registration
Statement for  the  respective bonds  comprising  the trust  portfolio  are  the
ratings currently indicated in our KENNYBASE database.
 
   You  are hereby authorized to file a  copy of this letter with the Securities
and Exchange Commission.
 
Sincerely,
 
Frank A. Ciccotto

<PAGE>
EXHIBIT 4.3
 
(ON CARTER LEDYARD & MILBURN LETTERHEAD)
 
   
March 25, 1998
    
 
Nuveen Tax-Free Unit Trust, Series 990
c/o John Nuveen & Co. Incorporated,
as Depositor of
Nuveen Tax-Free Unit Trust, Series 990
333 W. Wacker Drive
Chicago, Illinois 60606
 
RE:  Nuveen Tax-Free Unit Trust, Series 990
 
Dear Sirs:
 
   We hereby consent to the reference to our firm under the caption "What is the
Tax Status of Unitholders?" in the Registration Statement and related Prospectus
of  Nuveen Tax-Free  Unit Trust,  Series 990  for the  registration of  units of
fractional undivided interest in the Fund  in the aggregate principal amount  as
set forth in the Closing Memorandum dated today's date.
 
Very truly yours,
 
CARTER, LEDYARD & MILBURN

<PAGE>
EXHIBIT 4.4
 
CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
   As independent public accountants, we hereby consent to the use of our report
and  to  all  references  to  our  Firm included  in  or  made  a  part  of this
Registration Statement.
 
ARTHUR ANDERSEN LLP
 
Chicago, Illinois
 
   
March 25, 1998
    

<TABLE> <S> <C>

<PAGE>
<ARTICLE> 6
<LEGEND>
This   schedule  contains  summary  financial  information  extracted  from  the
Massachusetts Insured Trust 152  which is incorporated  in the Prospectus  dated
March  25,  1998  and  is  qualified  in  its  entirety  by  reference  to  such
prospectus.
</LEGEND>
<SERIES>
<NUMBER>                     001
<NAME>                        Massachusetts Insured
 
       
<S>                                                <C>
<PERIOD-TYPE>                                      OTHER
<FISCAL-YEAR-END>                                               FEB-28-1999
<PERIOD-END>                                                    FEB-28-1999
<INVESTMENTS-AT-COST>                                             1,665,166
<INVESTMENTS-AT-VALUE>                                            1,669,616
<RECEIVABLES>                                                        17,498
<ASSETS-OTHER>                                                            0
<OTHER-ITEMS-ASSETS>                                                      0
<TOTAL-ASSETS>                                                    1,689,714
<PAYABLE-FOR-SECURITIES>                                                  0
<SENIOR-LONG-TERM-DEBT>                                                   0
<OTHER-ITEMS-LIABILITIES>                                            17,498
<TOTAL-LIABILITIES>                                                  17,498
<SENIOR-EQUITY>                                                           0
<PAID-IN-CAPITAL-COMMON>                                                  0
<SHARES-COMMON-STOCK>                                                17,500
<SHARES-COMMON-PRIOR>                                                     0
<ACCUMULATED-NII-CURRENT>                                                 0
<OVERDISTRIBUTION-NII>                                                    0
<ACCUMULATED-NET-GAINS>                                                   0
<OVERDISTRIBUTION-GAINS>                                                  0
<ACCUM-APPREC-OR-DEPREC>                                                  0
<NET-ASSETS>                                                      1,669,616
<DIVIDEND-INCOME>                                                         0
<INTEREST-INCOME>                                                         0
<OTHER-INCOME>                                                            0
<EXPENSES-NET>                                                            0
<NET-INVESTMENT-INCOME>                                                   0
<REALIZED-GAINS-CURRENT>                                                  0
<APPREC-INCREASE-CURRENT>                                                 0
<NET-CHANGE-FROM-OPS>                                                     0
<EQUALIZATION>                                                            0
<DISTRIBUTIONS-OF-INCOME>                                                 0
<DISTRIBUTIONS-OF-GAINS>                                                  0
<DISTRIBUTIONS-OTHER>                                                     0
<NUMBER-OF-SHARES-SOLD>                                                   0
<NUMBER-OF-SHARES-REDEEMED>                                               0
<SHARES-REINVESTED>                                                       0
<NET-CHANGE-IN-ASSETS>                                                    0
<ACCUMULATED-NII-PRIOR>                                                   0
<ACCUMULATED-GAINS-PRIOR>                                                 0
<OVERDISTRIB-NII-PRIOR>                                                   0
<OVERDIST-NET-GAINS-PRIOR>                                                0
<GROSS-ADVISORY-FEES>                                                     0
<INTEREST-EXPENSE>                                                        0
<GROSS-EXPENSE>                                                           0
<AVERAGE-NET-ASSETS>                                                      0
<PER-SHARE-NAV-BEGIN>                                                 95.41
<PER-SHARE-NII>                                                           0
<PER-SHARE-GAIN-APPREC>                                                   0
<PER-SHARE-DIVIDEND>                                                      0
<PER-SHARE-DISTRIBUTIONS>                                                 0
<RETURNS-OF-CAPITAL>                                                      0
<PER-SHARE-NAV-END>                                                       0
<EXPENSE-RATIO>                                                           0
<AVG-DEBT-OUTSTANDING>                                                    0
<AVG-DEBT-PER-SHARE>                                                      0
        

</TABLE>

<TABLE> <S> <C>

<PAGE>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information extracted from the New York
Insured  Trust 278 which is incorporated in  the Prospectus dated March 25, 1998
and is qualified in its entirety by reference to such prospectus.
</LEGEND>
<SERIES>
<NUMBER>                     002
<NAME>                        New York Insured
 
       
<S>                                                <C>
<PERIOD-TYPE>                                      OTHER
<FISCAL-YEAR-END>                                               FEB-28-1999
<PERIOD-END>                                                    FEB-28-1999
<INVESTMENTS-AT-COST>                                             1,694,278
<INVESTMENTS-AT-VALUE>                                            1,700,793
<RECEIVABLES>                                                        23,789
<ASSETS-OTHER>                                                            0
<OTHER-ITEMS-ASSETS>                                                      0
<TOTAL-ASSETS>                                                    1,727,082
<PAYABLE-FOR-SECURITIES>                                                  0
<SENIOR-LONG-TERM-DEBT>                                                   0
<OTHER-ITEMS-LIABILITIES>                                            23,789
<TOTAL-LIABILITIES>                                                  23,789
<SENIOR-EQUITY>                                                           0
<PAID-IN-CAPITAL-COMMON>                                                  0
<SHARES-COMMON-STOCK>                                                17,500
<SHARES-COMMON-PRIOR>                                                     0
<ACCUMULATED-NII-CURRENT>                                                 0
<OVERDISTRIBUTION-NII>                                                    0
<ACCUMULATED-NET-GAINS>                                                   0
<OVERDISTRIBUTION-GAINS>                                                  0
<ACCUM-APPREC-OR-DEPREC>                                                  0
<NET-ASSETS>                                                      1,700,793
<DIVIDEND-INCOME>                                                         0
<INTEREST-INCOME>                                                         0
<OTHER-INCOME>                                                            0
<EXPENSES-NET>                                                            0
<NET-INVESTMENT-INCOME>                                                   0
<REALIZED-GAINS-CURRENT>                                                  0
<APPREC-INCREASE-CURRENT>                                                 0
<NET-CHANGE-FROM-OPS>                                                     0
<EQUALIZATION>                                                            0
<DISTRIBUTIONS-OF-INCOME>                                                 0
<DISTRIBUTIONS-OF-GAINS>                                                  0
<DISTRIBUTIONS-OTHER>                                                     0
<NUMBER-OF-SHARES-SOLD>                                                   0
<NUMBER-OF-SHARES-REDEEMED>                                               0
<SHARES-REINVESTED>                                                       0
<NET-CHANGE-IN-ASSETS>                                                    0
<ACCUMULATED-NII-PRIOR>                                                   0
<ACCUMULATED-GAINS-PRIOR>                                                 0
<OVERDISTRIB-NII-PRIOR>                                                   0
<OVERDIST-NET-GAINS-PRIOR>                                                0
<GROSS-ADVISORY-FEES>                                                     0
<INTEREST-EXPENSE>                                                        0
<GROSS-EXPENSE>                                                           0
<AVERAGE-NET-ASSETS>                                                      0
<PER-SHARE-NAV-BEGIN>                                                 97.19
<PER-SHARE-NII>                                                           0
<PER-SHARE-GAIN-APPREC>                                                   0
<PER-SHARE-DIVIDEND>                                                      0
<PER-SHARE-DISTRIBUTIONS>                                                 0
<RETURNS-OF-CAPITAL>                                                      0
<PER-SHARE-NAV-END>                                                       0
<EXPENSE-RATIO>                                                           0
<AVG-DEBT-OUTSTANDING>                                                    0
<AVG-DEBT-PER-SHARE>                                                      0
        

</TABLE>

<TABLE> <S> <C>

<PAGE>
<ARTICLE> 6
<LEGEND>
This   schedule  contains  summary  financial  information  extracted  from  the
Pennsylvania Insured Trust  234 which  is incorporated in  the Prospectus  dated
March  25,  1998  and  is  qualified  in  its  entirety  by  reference  to  such
prospectus.
</LEGEND>
<SERIES>
<NUMBER>                     003
<NAME>                        Pennsylvania Insured
 
       
<S>                                                <C>
<PERIOD-TYPE>                                      OTHER
<FISCAL-YEAR-END>                                               FEB-28-1999
<PERIOD-END>                                                    FEB-28-1999
<INVESTMENTS-AT-COST>                                             1,661,328
<INVESTMENTS-AT-VALUE>                                            1,665,604
<RECEIVABLES>                                                        22,301
<ASSETS-OTHER>                                                            0
<OTHER-ITEMS-ASSETS>                                                      0
<TOTAL-ASSETS>                                                    1,690,605
<PAYABLE-FOR-SECURITIES>                                                  0
<SENIOR-LONG-TERM-DEBT>                                                   0
<OTHER-ITEMS-LIABILITIES>                                            22,301
<TOTAL-LIABILITIES>                                                  22,301
<SENIOR-EQUITY>                                                           0
<PAID-IN-CAPITAL-COMMON>                                                  0
<SHARES-COMMON-STOCK>                                                17,500
<SHARES-COMMON-PRIOR>                                                     0
<ACCUMULATED-NII-CURRENT>                                                 0
<OVERDISTRIBUTION-NII>                                                    0
<ACCUMULATED-NET-GAINS>                                                   0
<OVERDISTRIBUTION-GAINS>                                                  0
<ACCUM-APPREC-OR-DEPREC>                                                  0
<NET-ASSETS>                                                      1,665,604
<DIVIDEND-INCOME>                                                         0
<INTEREST-INCOME>                                                         0
<OTHER-INCOME>                                                            0
<EXPENSES-NET>                                                            0
<NET-INVESTMENT-INCOME>                                                   0
<REALIZED-GAINS-CURRENT>                                                  0
<APPREC-INCREASE-CURRENT>                                                 0
<NET-CHANGE-FROM-OPS>                                                     0
<EQUALIZATION>                                                            0
<DISTRIBUTIONS-OF-INCOME>                                                 0
<DISTRIBUTIONS-OF-GAINS>                                                  0
<DISTRIBUTIONS-OTHER>                                                     0
<NUMBER-OF-SHARES-SOLD>                                                   0
<NUMBER-OF-SHARES-REDEEMED>                                               0
<SHARES-REINVESTED>                                                       0
<NET-CHANGE-IN-ASSETS>                                                    0
<ACCUMULATED-NII-PRIOR>                                                   0
<ACCUMULATED-GAINS-PRIOR>                                                 0
<OVERDISTRIB-NII-PRIOR>                                                   0
<OVERDIST-NET-GAINS-PRIOR>                                                0
<GROSS-ADVISORY-FEES>                                                     0
<INTEREST-EXPENSE>                                                        0
<GROSS-EXPENSE>                                                           0
<AVERAGE-NET-ASSETS>                                                      0
<PER-SHARE-NAV-BEGIN>                                                 95.18
<PER-SHARE-NII>                                                           0
<PER-SHARE-GAIN-APPREC>                                                   0
<PER-SHARE-DIVIDEND>                                                      0
<PER-SHARE-DISTRIBUTIONS>                                                 0
<RETURNS-OF-CAPITAL>                                                      0
<PER-SHARE-NAV-END>                                                       0
<EXPENSE-RATIO>                                                           0
<AVG-DEBT-OUTSTANDING>                                                    0
<AVG-DEBT-PER-SHARE>                                                      0
        

</TABLE>

<PAGE>
MEMORANDUM
 
                     NUVEEN TAX-FREE UNIT TRUST, SERIES 990
                               FILE NO. 333-46763
 
   
   The  Prospectus  and  the  Indenture  filed  with  Amendment  No.  1  of  the
Registration Statement  on Form  S-6 have  been revised  to reflect  information
regarding  the execution of the Indenture and  the deposit of bonds on March 25,
1998, and to  set forth  certain statistical  data based  thereon. In  addition,
there  are a number of other changes  from the Prospectus as originally filed to
which reference is  made, including  the increase  in the  size of  the Fund,  a
corresponding  increase in the  number of Units  and a change  in the individual
trusts constituting the Fund.  All references to the  Units, prices and  related
statistical  data will  apply to each  trust of  the Fund and  the Units thereof
individually.
    
 
   Except for such updating, an effort has been made to set forth below each  of
the  changes and also to reflect the  same by marking the Prospectus transmitted
with the Amendment. Also, differences  between the Final Prospectus relating  to
the  previous  series  of  the  Nuveen Tax-Exempt  Unit  Trust  and  the subject
Prospectus have been indicated.
 
FORM S-6
 
FACING SHEET. The file number is now shown.
 
THE PROSPECTUS
 
   PART A-PAGE  2.--The  "Estimated  Long-Term Return"  and  "Estimated  Current
Return" to Unitholders under each Trust under each of the distribution plans are
stated.
 
   PART  A-PAGES 1-2.--Essential information  for each of  the Trusts, including
applicable footnotes, has been completed for this Series.
 
   PART A-PAGES 1-2.--The date of the  Indenture has been inserted in Section  1
along with the size and number of Units of each of the Trusts.
 
   PART A-PAGES 1-7 et seq.--The following information for each Trust appears on
the pages relating to such trust:
 
       The  estimated daily accrual of interest  under the plans of distribution
       for each of the Trusts
 
       Data regarding the composition of the portfolio of each Trust
 
       Disclosure  regarding  the  states'  economic  and  legislative   matters
       relevant to investors of state trusts
 
       Concentrations of issues by purpose in each Trust
 
       The  approximate percentage of  the bonds in the  portfolio of each Trust
       acquired  in  distributions  where  the  Sponsor  was  either  the   sole
       underwriter or manager or member of the underwriting syndicate
 
       The percentage of "when issued" bonds in the portfolio of each Trust
 
       The schedule of investments for each Trust, including the notes thereto
 
       Descriptions of the opinions of the special tax counsel for state trusts
 
       The  Record Dates and  Distribution Dates for  interest distributions for
       each Trust
 
       The Statements of Condition  for each Trust  and the Accountant's  Report
       with regard thereto.
 
       The amount of the Trustee's Fee
 
CHAPMAN AND CUTLER
 
Chicago, Illinois
 
   
March 25, 1998
    


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