<PAGE>
As filed with the Securities and Exchange Commission on April 17, 1997
Registration No. 33-55833
==========================================================================
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
___________________
POST-EFFECTIVE AMENDMENT NO. 2 TO
FORM S-6
FOR REGISTRATION UNDER THE SECURITIES ACT
OF 1933 OF SECURITIES OF UNIT INVESTMENT
TRUSTS REGISTERED ON FORM N-8B-2
___________________
A. Exact Name of Trust:
NATIONAL MUNICIPAL TRUST,
Series 173
B. Name of depositor:
PRUDENTIAL SECURITIES INCORPORATED
C. Complete address of depositor's principal executive office:
One Seaport Plaza
199 Water Street
New York, New York 10292
D. Name and complete address of agent for service:
Copy to:
LEE B. SPENCER, JR., ESQ. KENNETH W. ORCE, ESQ.
PRUDENTIAL SECURITIES INCORPORATED CAHILL GORDON & REINDEL
One Seaport Plaza 80 Pine Street
199 Water Street New York, New York 10005
New York, New York 10292
It is proposed that this filing will become effective (check appropriate
box.)
___
/ / immediately upon filing on (date) pursuant to paragraph (b);
___
/X / on April 30, 1997 pursuant to paragraph (b);
___
/__/ 60 days after filing pursuant to paragraph (a);
___
/__/ on (date) pursuant to paragraph (a) of rule 485.
<PAGE>
CUSIP: 63701J595 MAIL CODE A
Prospectus--PART A
NOTE: PART A of this Prospectus may not be distributed unless accompanied by
Part B.
- --------------------------------------------------------------------------------
NATIONAL MUNICIPAL TRUST
NMT Series 173
- --------------------------------------------------------------------------------
The initial public offering of Units in the Trust has been completed. The Units
offered hereby are issued and outstanding Units which have been acquired by the
Sponsor either by purchase from the Trustee of Units tendered for redemption or
in the secondary market.
The objectives of the Trust are the providing of interest income which, in the
opinion of counsel is, under existing law, excludable from gross income for
Federal income tax purposes (except in certain instances depending on the Unit
Holder), through investment in a fixed portfolio of long-term debt obligations
issued on behalf of states, counties, municipalities, authorities and political
subdivisions thereof, and territories, or possessions of the United States, and
the conservation of capital. There is, of course, no guarantee that the Trust's
objectives will be achieved. The value of the Units of the Trust will fluctuate
with the value of the portfolio of underlying Securities. The Securities in the
Trust are not insured by The Prudential Insurance Company of America. The
Prospectus indicates the extent to which interest income of the Trust is subject
to alternative minimum tax under the Internal Revenue Code of 1986, as amended.
See 'Schedule of Portfolio Securities' and 'Portfolio Summary.'
Minimum Purchase : 1 Unit.
PUBLIC OFFERING PRICE of the Units of the Trust is equal to the aggregate bid
side evaluation of the underlying Securities in the Trust's Portfolio divided by
the number of Units outstanding in such Trust, plus a sales charge as set forth
in the table herein. (See Part B--'Public Offering of Units--Volume Discount.')
Units are offered at the Public Offering Price plus accrued interest. (See Part
B--'Public Offering of Units.')
- --------------------------------------------------------------------------------
Sponsor:
Prudential Securities (LOGO)
- --------------------------------------------------------------------------------
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.
- --------------------------------------------------------------------------------
Please read and retain Prospectus dated
this Prospectus for future reference April 30, 1997
<PAGE>
NATIONAL MUNICIPAL TRUST
Series 173
- --------------------------------------------------------------------------------
TABLE OF CONTENTS
- --------------------------------------------------------------------------------
<TABLE>
<CAPTION>
Page
<S> <C> <C>
Summary.................................................................................. Part A A-i
Summary of Essential Information......................................................... A-iii
Independent Auditors' Report............................................................. A-1
Statement of Financial Condition......................................................... A-2
Schedule of Portfolio Securities......................................................... A-7
The Trust................................................................................ Part B 1
Portfolio Summary................................................................... 2
Insurance on the Securities in the Portfolio of an Insured Trust--General........... 9
Insurance on the Securities in the Portfolio of an Insured Trust--Insurers.......... 9
Objectives and Securities Selection................................................. 14
Estimated Annual Income Per Unit.................................................... 14
Tax Status............................................................................... 15
Public Offering of Units................................................................. 18
Public Offering Price............................................................... 18
Public Distribution................................................................. 19
Secondary Market.................................................................... 20
Sponsor's and Underwriters' Profits................................................. 20
Secondary Market Sales Charge....................................................... 20
Volume Discount..................................................................... 21
Employee Discount................................................................... 21
Exchange Option.......................................................................... 21
Tax Consequences.................................................................... 23
Reinvestment Program..................................................................... 23
Expenses and Charges..................................................................... 23
Expenses............................................................................ 23
Fees................................................................................ 23
Other Charges....................................................................... 25
Rights of Unit Holders................................................................... 25
Certificates........................................................................ 25
Distribution of Interest and Principal.............................................. 25
Reports and Records................................................................. 27
Redemption.......................................................................... 27
Sponsor.................................................................................. 28
Limitations on Liability............................................................ 29
Responsibility...................................................................... 30
Resignation......................................................................... 30
Trustee.................................................................................. 30
Limitations on Liability............................................................ 31
Responsibility...................................................................... 31
Resignation......................................................................... 31
Evaluator................................................................................ 31
Limitations on Liability............................................................ 31
Responsibility...................................................................... 31
Resignation......................................................................... 31
Amendment and Termination of the Indenture............................................... 32
Amendment........................................................................... 32
Termination......................................................................... 32
Legal Opinions........................................................................... 32
Auditors................................................................................. 32
Bond Ratings............................................................................. 32
</TABLE>
<PAGE>
- --------------------------------------------------------------------------------
This Prospectus does not contain all of the information with respect to the
investment company set forth in its registration statement and exhibits relating
thereto which have been filed with the Securities and Exchange Commission,
Washington, D.C. under the Securities Act of 1933 and the Investment Company Act
of 1940, and to which reference is hereby made.
- --------------------------------------------------------------------------------
No person is authorized to give any information or to make any representations
with respect to this investment company not contained herein; and any
information or representations not contained herein must not be relied upon as
having been authorized. 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.
- --------------------------------------------------------------------------------
SUMMARY
NATIONAL MUNICIPAL TRUST, Series 173 (the 'National Trust' or the 'Trust' as
the context requires) is composed of interest-bearing municipal bonds (the
'Securities.') The interest on these bonds, in the opinion of bond counsel to
the issuing governmental authorities is, under existing law, excludable from
gross income for Federal income tax purposes (except in certain instances
depending on the Unit Holder). The Securities in the Trust were, as of the Date
of Deposit rated in the category of 'A' or better by Standard & Poor's
Corporation or by Moody's Investors Service. (See Part B--'Bond Ratings.')
MONTHLY DISTRIBUTIONS of principal, premium, if any, and interest received
by the Trust will be made on or shortly after the twenty-fifth day of each month
to Unit Holders of record as of the immediately preceding Record Date. In some
cases, distribution on a semi-annual basis may be available. (See Part
B--'Rights of Unit Holders--Distribution of Interest and Principal.')
Alternatively, Unit Holders may elect to have their distributions reinvested in
the Reinvestment Program of the Sponsor, as, if and when such program is
available to Unit Holders. (See Part B--'Reinvestment Program.')
THE SPONSOR, although not obligated to do so, presently intends to maintain
a secondary market for the Units in the Trust based on the aggregate bid side
evaluation of the underlying Securities, as more fully described under Part
B--'Public Offering of Units--Secondary Market.' If such a market is not
maintained, a Unit Holder may be able to dispose of his Units only through
redemption at prices based on the aggregate bid side evaluation of the
underlying Securities. (See Part B--'Rights of Unit
Holders--Redemption--Computation of Redemption Price per Unit.')
SPECIAL CONSIDERATIONS. An investment in Units of the Trust should be made
with an understanding of the risks which an investment in fixed rate long-term
debt obligations may entail, including the risk that the value of the Units will
decline with increases in interest rates. (See Part B--'The Trust--Portfolio
Summary.') The ratings of the Securities set forth in Part A--'Schedule of
Portfolio Securities' may have declined due to, among other factors, a decline
in creditworthiness of the issuer of said Securities.
Note: In Part B 'Trustee' the location of the unit investment trust office
of The Chase Manhattan Bank is amended to read 4 New York Plaza, New York, New
York 10004.
Portfolio Summary
National Trust
The Portfolio contains 11 issues of Securities of issuers located in 10
states. All of the issues are payable from the income of specific projects or
authorities and are not supported by the issuer's power to levy taxes. Although
income to pay such Securities may be derived from more than one source, the
primary sources of such income and the percentage of issues deriving income from
such sources are as follows; airport facilities: 10.8%* of the Trust; health and
hospital facilities: 20.6%* of the Trust; housing facilities: 28.2%* of the
Trust; lease facilities: 10.4%* of the Trust; revenue facilities: 11.1%* of the
Trust; utility facilities: 18.9%* of the Trust. The Trust is concentrated in
housing facilities Securities.
The Portfolio also contains Securities representing 28.2%* of the Trust
(single-family housing securities) which are subject to the requirements of
Section 103A of the Internal Revenue Code of 1954, as amended, or Section 143 of
the Internal Revenue Code of 1986, as amended.
- ------------
* Percentages computed on the basis of the aggregate bid price of the
Securities in the Trust on March 17, 1997.
A-i
<PAGE>
Approximately 28.2% of the Securities in the Trust also contain provisions
which require the issuer to redeem such obligations at par from unused proceeds
of the issue within a stated period which typically does not exceed three years
from the date of issuance of such Securities.
63.1%* of the Securities in the Trust are rated by Standard & Poor's
Corporation (10.5%* being rated AAA, 10.4%* being rated AA and 42.2%* being
rated A) and 36.9%* of the Securities in the Trust are rated by Moody's
Investors Service (7.9%* being rated Aa and 21.3%* being rated A and 7.7%* being
rated Baa). For a description of the meaning of the applicable rating symbols as
published by Standard & Poor's and Moody's, see Part B--'Bond Ratings.' It
should be emphasized, however, that the ratings of Standard & Poor's and Moody's
represent their opinions as to the quality of the Securities which they
undertake to rate and that these ratings are general and are not absolute
standards of quality.
Seven Securities in the Trust have been issued with an 'original issue
discount.' (See Part B--'Tax Status.')
Of these original issue discount bonds, approximately 2.6% of the aggregate
principal amount of the Securities in the Trust (although only 0.5%* of the
aggregate bid price of all Securities in the Trust) are zero coupon bonds
(including bonds known as multiplier bonds, money multiplier bonds, capital
appreciation bonds, capital accumulator bonds, compound interest bonds, and
discount maturity payment bonds).
Alternative Minimum Tax
The Sponsor's affiliate, The Prudential Investment Corporation, estimates
that 61.4% of the estimated net annual income per Unit consists of interest on
private activity bonds, which interest is to be treated as a tax preference item
for alternative minimum tax purposes. (See 'Tax Status' and 'Schedule of
Portfolio Securities.')
- ------------
* Percentages computed on the basis of the aggregate bid price of the
Securities in the Trust on March 17, 1997.
A-ii
<PAGE>
SUMMARY OF ESSENTIAL INFORMATION
NATIONAL MUNICIPAL TRUST
Series 173
As of March 17, 1997
<TABLE>
<S> <C>
FACE AMOUNT OF SECURITIES......................... $ 9,695,000.00
NUMBER OF UNITS................................... 10,000
FRACTIONAL UNDIVIDED INTEREST IN THE TRUST
REPRESENTED BY EACH UNIT........................ 1/10,000th
PUBLIC OFFERING PRICE
Aggregate bid side evaluation of Securities in
the Trust..................................... $ 9,899,469.40
Divided by 10,000 Units......................... $ 989.95
Plus sales charge of 5.500% of Public Offering
Price (5.820% of net amount invested in
Securities)................................... $ 57.62
--------------
Public Offering Price per Unit(2)(4)............ $ 1,047.57
--------------
--------------
REDEMPTION PRICE AND SPONSOR'S REPURCHASE PRICE
PER UNIT (based on bid side evaluation of
underlying Securities, $57.62 less than Public
Offering Price per Unit)(4)..................... $ 989.95
--------------
--------------
MINIMUM PRINCIPAL DISTRIBUTION: No distribution need be made from
the Principal Account if the balance therein is less than $5
per Unit.
SPONSOR'S ANNUAL PORTFOLIO SUPERVISION FEE: Maximum $.25 per
$1,000 face amount of underlying Securities.
PREMIUM AND DISCOUNT ISSUES IN PORTFOLIO:
Face amount of Securities with bid side evaluation:
over par--97.4%; at par--0%; at a discount from par--2.6%
EVALUATOR'S FEE FOR EACH EVALUATION: Maximum of $14.
EVALUATION TIME: 3:30 P.M. New York time.
MANDATORY TERMINATION DATE: The Trust will terminate on the date
of the maturity, redemption, sale or other disposition of the
last Security held in the Trust.
MINIMUM VALUE OF TRUST: The Trust may be terminated if the value
of the Trust is less than $4,000,000.00
Percentage of Unit Holders required to consent in order to amend
(as permitted) the Trust Indenture and Agreement (except under
certain circumstances when Unit Holder consent is not
required).................................................. 51%
Percentage of Unit Holders required to consent in order to
terminate the Trust........................................ 51%
DATE OF DEPOSIT: January 24, 1995(1)
</TABLE>
<TABLE>
<CAPTION>
Monthly
-------
<S> <C>
CALCULATION OF ESTIMATED NET ANNUAL INCOME PER UNIT
Estimated Annual Income per Unit............................................................... $64.00
Less estimated annual expenses per Unit(3)..................................................... (2.25)
-------
Estimated Net Annual Income per Unit........................................................... $61.75
-------
-------
Trustee's Annual Fee (including estimated expenses and Evaluator's fee)
per $1,000 principal amount of underlying Securities........................................... $ 2.00
Daily Rate of Income Accrual per Unit............................................................ $.1715
Estimated Current Return (based on Public Offering Price)(5)(6).................................. 5.89%
Estimated Long-Term Return(6).................................................................... 5.48%
INTEREST DISTRIBUTION
Estimated Net Annual Income per Unit / 12...................................................... $ 5.14
Record Dates--tenth day of each month
Distribution Dates--twenty-fifth day of each month
</TABLE>
- ------------
(1) The Date of Deposit is the date on which the Indenture was signed and
the deposit of Securities with the Trustee was made.
(2) This Public Offering Price is computed as of March 17, 1997 and may vary
from the Public Offering Price on the date of this Prospectus or any subsequent
date.
(3) Includes Trustee's fee, Sponsor's Portfolio supervision fee, estimated
expenses and Evaluator's fees.
(4) Exclusive of accrued interest which to March 20, 1997, the expected date
of settlement for the purchase of Units on March 17, 1997 was $2.57.
(5) The estimated current return is increased for transactions entitled to a
reduced sales charge. (See Part B--'The Trust'--'Estimated Annual Income and
Current Return per Unit.')
(6) The Estimated Current Return is calculated by dividing the Estimated Net
Annual Income per Unit by the Public Offering Price per Unit. The Estimated Net
Annual Income per Unit will vary with changes in fees and expenses of the
Trustee and the Evaluator and with the principal prepayment, redemption,
maturity, exchange or sale of Securities while the Public Offering Price will
vary with changes in the bid price of the underlying Securities; therefore,
there is no assurance that the present Estimated Current Return indicated above
will be realized in the future. The Estimated Long-Term Return is calculated on
a pre-tax basis using a formula which takes into consideration, and factors in
the relative weightings of, the market values, yields (which takes into account
the amortization of premiums and the accretion of discounts) and estimated
retirements of all of the Securities in the Trust and takes into account the
expenses and sales charge associated with each Unit. Since the market values and
estimated retirements of the Securities and the expenses of the Trust will
change, there is no assurance that the present Estimated Long-Term Return as
indicated above will be realized in the future. The after-tax Estimated
Long-Term Return will be lower to the extent of any taxation on the disposition
of Securities. The Estimated Current Return and Estimated Long-Term Return are
expected to differ because the calculation of the Estimated Long-Term Return
reflects the estimated date and amount of principal returned while the Estimated
Current Return calculations include only Net Annual Interest Income and Public
Offering Price as of the above indicated calculation date of the Summary of
Essential Information.
A-iii
<PAGE>
<AUDIT-REPORT>
INDEPENDENT AUDITORS' REPORT
THE UNIT HOLDERS, SPONSOR AND TRUSTEE
NATIONAL MUNICIPAL TRUST
SERIES 173
We have audited the statement of financial condition and schedule of
portfolio securities of the National Municipal Trust Series 173 as of
December 31, 1996 and the related statements of operations and changes in
net assets for the year ended December 31, 1996 and the period from
January 24, 1995 (date of deposit) to December 31, 1995. These financial
statements are the responsibility of the Trustee (see Footnote (a)(1)). 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 securities owned as of
December 31, 1996 as shown in the statement of financial condition and
schedule of portfolio securities by correspondence with The Chase Manhattan
Bank, the Trustee. An audit also includes assessing the accounting
principles used and the significant estimates made by the Trustee, 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 financial statements referred to above present fairly,
in all material respects, the financial position of the National Municipal
Trust Series 173 as of December 31, 1996, and the results of its operations
and the changes in its net assets for the year ended December 31, 1996 and
the period from January 24, 1995 (date of deposit) to December 31, 1995 in
conformity with generally accepted accounting principles.
DELOITTE & TOUCHE LLP
DELOITTE & TOUCHE LLP
April 1, 1997
New York, New York
</AUDIT-REPORT>
A-1
<PAGE>
STATEMENT OF FINANCIAL CONDITION
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
TRUST PROPERTY
<TABLE>
<S> <C>
Investments in municipal bonds at market value
(amortized cost $9,285,804) (Note (a) and Schedule of
Portfolio Securities Notes (4) and (5)) $10,077,291
Accrued interest receivable 227,318
Total 10,304,609
LIABILITIES AND NET ASSETS
Less Liabilities:
Due to Trustee 187,252
Accrued Trust fees and expenses 8,089
Total liabilities 195,341
Net Assets:
Balance applicable to 10,000 Units of fractional
undivided interest outstanding (Note (c)):
Capital, plus unrealized market
appreciation of $791,487 $10,077,291
Undistributed net investment income (Note (b)) 31,977
Net assets $10,109,268
Net asset value per Unit ($10,109,268 divided by 10,000 Units) $ 1,010.93
</TABLE>
See notes to financial statements
A-2
<PAGE>
STATEMENTS OF OPERATIONS
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
<TABLE>
<CAPTION>
For the period from
January 24, 1995
For the year ended (date of deposit) to
December 31, 1996 December 31, 1995
<S> <C> <C>
Investment income - interest $654,496 $ 607,467
Less expenses:
Trust fees and expenses 22,207 23,569
Total expenses 22,207 23,569
Investment income - net 632,289 583,898
Net (loss) gain on investments:
Realized gain on securities sold or
redeemed 3,776 750
Unrealized market (depreciation)
appreciation (71,379) 862,866
Net (loss) gain on investments (67,603) 863,616
Net increase in net assets resulting from
operations $564,686 $1,447,514
</TABLE>
See notes to financial statements
A-3
<PAGE>
STATEMENTS OF CHANGES IN NET ASSETS
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
<TABLE>
<CAPTION>
For the period from
January 24, 1995
For the year ended (date of deposit) to
December 31, 1996 December 31, 1995
<S> <C> <C>
Operations:
Investment income - net $ 632,289 $ 583,898
Realized gain on securities sold or
redeemed 3,776 750
Unrealized market (depreciation)
appreciation (71,379) 862,866
Net increase in net assets
resulting from operations 564,686 1,447,514
Less Distributions to Unit Holders:
Principal (185,000) -
Investment income - net (633,000) (545,800)
Total distributions (818,000) (545,800)
Net (decrease) increase in net assets (253,314) 901,714
Net assets:
Beginning of period (Note c) 10,362,582 9,460,868
End of period (including undistributed net
investment income of $31,977 and undis-
tributed principal and net investment
income of $65,522, respectively) $10,109,268 $10,362,582
</TABLE>
See notes to financial statements
A-4
<PAGE>
NOTES TO FINANCIAL STATEMENTS
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
(a) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
The Trustee is registered under the Investment Company Act of 1940 as a
Unit Investment Trust. The following is a summary of the significant
accounting policies of the Trust:
(1) Basis of Presentation
The Trustee has custody of and responsibility for all accounting and
financial books, records, financial statements and related data of
the Trust and is responsible for establishing and maintaining a
system of internal controls directly related to, and designed to
provide reasonable assurance as to the integrity and reliability
of, financial reporting of the Trust. The Trustee is also
responsible for all estimates and accruals reflected in the Trust's
financial statements. The Evaluator determines the price for each
underlying Security included in the Trust's Schedule of Portfolio
Securities on the basis set forth in Part B of this Prospectus,
"Public Offering of Units - Public Offering Price". Under the
Securities Act of 1933 ("the Act"), as amended, the Sponsor is
deemed to be an issuer of the Trust Units. As such, the Sponsor
has the responsibility of an issuer under the Act with respect to
financial statements of the Trust included in the Registration
Statement under the Act and amendments thereto.
(2) Investments
Investments are stated at market value as determined by the
Evaluator based on the bid side evaluations on the last day of
trading during the period, except that value on the date of deposit
(January 24, 1995) represents the cost of investments to the Trust
based on the offering side evaluations as of the date of deposit.
(3) Income Taxes
The Trust is not an association taxable as a corporation for Federal
income tax purposes; accordingly, no provision is required for such
taxes.
(4) Expenses
The Trustee pays an annual Trustee's fee, including estimated
expenses, Evaluator's fee and an annual Sponsor portfolio
supervision fee and may incur additional charges as explained
under "Expenses and Charges - Fees" and "- Other Charges" in Part B
of this Prospectus.
(b) DISTRIBUTIONS
Interest received by the Trust is distributed to the Unit Holders on or
shortly after the twenty-fifth day of each month after deducting
applicable expenses. Receipts other than interest are distributed as
explained in "Rights of Unit Holders - Distribution of Interest and
Principal" in Part B of this Prospectus.
A-5
<PAGE>
NOTES TO FINANCIAL STATEMENTS
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
(c) ORIGINAL COST TO INVESTORS
The original cost to investors represents the aggregate initial public
offering price as of the date of deposit (January 24, 1995) exclusive of
accrued interest.
A reconciliation of the original cost of Units to investors to the net
amount applicable to investors as of December 31, 1996 follows:
<TABLE>
<S> <C>
Original cost to investors $ 9,932,700
Less: Gross underwriting commissions (sales charge) (471,832)
Net cost to investors 9,460,868
Cost of securities sold or redeemed (180,475)
Unrealized market appreciation 791,487
Accumulated interest accretion 5,411
Net amount applicable to investors $10,077,291
</TABLE>
(d) OTHER INFORMATION
Selected data for a Unit of the Trust during each period:
<TABLE>
<CAPTION>
For the period from
January 24, 1995
For the year ended (date of deposit) to
December 31, 1996 December 31, 1995
<S> <C> <C>
Interest income $ 65.45 $ 60.75
Expenses (2.22) (2.36)
Investment income - net 63.23 58.39
Income distributions (63.30) (54.58)
.07 3.81
Principal distributions (18.50) -
Realized gain on securities
sold or redeemed .38 .08
Unrealized market (depreciation)
appreciation (7.14) 86.29
Net (decrease) increase in net
asset value (25.33) 90.18
Net asset value -- beginning
of period 1,036.26 946.08
Net asset value -- end of
period $1,010.93 $1,036.26
</TABLE>
A-6
<PAGE>
SCHEDULE OF PORTFOLIO SECURITIES
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
<TABLE>
<CAPTION>
Port- Optional
folio Rating Face Coupon Maturity Sinking Fund Refunding Market
No. Title of Securities <F1> Amount Rate Date Redemptions<F3> Redemptions<F2> Value
<F4><F5>
<C> <S> <C> <C> <C> <C> <C> <C> <C>
1. City of San Francisco,
Downtown Parking Corpora-
tion, Parking Revenue Bonds,
Series 1993. A<F6> $1,000,000 6.650% 04/01/18 04/01/13@100 04/01/03@102 $ 1,048,980
2. Regional Airport Improve-
ment Corp., Facilities Lease
Revenue Bonds, Issue of 1991,
LAXFUEL Corporation, (Los
Angeles International Air-
port). <F7> A- 1,000,000 6.800 01/01/27 01/01/23@100 01/01/02@102 1,041,710
3. State of Hawaii, Airports
System Revenue Bonds, Second
Series of 1991. <F7> A<F6> 1,000,000 7.000 07/01/18 07/01/13@100 07/01/01@102 1,073,090
4. Illinois Health Facilities
Authority, Revenue Bonds,
Series 1992, (Mercy Center
For Health Care Services). A- 1,000,000 6.650 10/01/22 10/01/13@100 10/01/02@102 1,027,050
5. North Carolina Eastern
Municipal Power Agency,
Power System Revenue Bonds,
Refunding Series 1991 A. Baa1<F6> 750,000 6.500 01/01/17 01/01/13@100 01/01/02@102 766,035
6. New York Energy Research
and Development Authority,
Facilities Revenue Bonds,
Series 1994 A, (Consolidated
Edison Company of New York,
Inc. Project). <F7> A+ 1,000,000 7.125 12/01/29 NONE 12/01/04@102 1,127,140
7. Delaware County Authority,
Hospital Revenue Bonds,
Series of 1992, (Riddle
Memorial Hospital). A- 1,000,000 6.500 01/01/22 01/01/03@100 01/01/02@100 1,018,530
8. South Dakota Housing
Development Authority, Home-
ownership Mortgage Bonds,
1994 Series F. <F7><F9> AAA 985,000 6.900 05/01/23 05/01/19@100 05/01/04@102 1,025,580
9. Utah Housing Finance
Agency, Single Family Mort-
gage Senior Bonds, 1992
Issue D, (Federally Insured
or Guaranteed Mortgage
Loans). <F7><F9> Aa<F6> 830,000 6.850 07/01/25 07/01/10@100 01/01/03@102 858,184
10. Bellvue Convention Center
Authority, King County,
Washington, Special Obliga-
tion Revenue and Refunding
Bonds, Series 1994, (Com-
pound Interest Bonds).
(MBIA Insured) <F8> AAA 250,000 0.000 02/01/23 NONE NONE 56,612
11. Wisconsin Housing & Econ-
omic Development Authority,
Home Ownership Revenue
Bonds, 1994 Series B. <F7> AA 1,000,000 6.750 09/01/25 09/01/21@100 03/01/04@102 1,034,380
$9,815,000 $10,077,291
</TABLE>
See notes to schedule of portfolio securities
A-7
<PAGE>
NOTES TO SCHEDULE OF PORTFOLIO SECURITIES
NATIONAL MUNICIPAL TRUST
SERIES 173
December 31, 1996
<F1> All ratings are provided by Standard & Poor's Corporation, unless
otherwise indicated. A brief description of applicable security
ratings is given under "Bond Ratings" in Part B of this Prospectus.
<F2> There is shown under this heading the date on which each issue of
Securities is redeemable by the operation of optional call
provisions and the redemption price for that date; unless otherwise
indicated, each issue continues to be redeemable at declining
prices thereafter but not below par. Securities listed as non-
callable, as well as Securities listed as callable, may also be
redeemable at par under certain circumstances from special
redemption payments.
<F3> There is shown under this heading the date on which an issue of
Securities is subject to scheduled sinking fund redemption and the
redemption price on such date.
<F4> The market value of the Securities as of December 31, 1996 was
determined by the Evaluator on the basis of bid side evaluations
for the Securities at such date.
<F5> At December 31, 1996, the unrealized market appreciation of all
Securities was comprised of the following:
<TABLE>
<S> <C>
Gross unrealized market appreciation $791,487
Gross unrealized market depreciation -
Unrealized market appreciation $791,487
</TABLE>
The amortized cost of the Securities for Federal income tax purposes
was $9,285,804 at December 31, 1996.
<F6> Moody's Investors Service, Inc. rating.
<F7> In the opinion of bond counsel to the issuing governmental
authorities, interest payments on these bonds will be a tax
preference item for individuals and corporations for alternative
minimum tax purposes. Normally, the bonds pay interest
semiannually. The payment dates can generally be determined based
on the date of maturity, i.e., a bond maturity on December 1 will
pay interest semiannually on June 1 and December 1. See "Tax
Status" in Part B of this Prospectus.
<F8> Insurance to maturity has been obtained by the Issuer from the
listed Insurance Company. The "AAA" rating on this Security is
based in part on the creditworthiness and claims-paying ability of
the Insurance Company insuring such Security to maturity.
<F9> $45,000 and $75,000 face amounts of Portfolio Nos. 8 and 9 were
called for redemption on January 2, 1997. Such Securities are
valued at the amount of the proceeds subsequently received.
A-8
<PAGE>
(MODULE)
[NAME] NMT-PUT-PTB-996
[CIK] 0000941856
[CCC] 3ttrjz#m
(/MODULE)
<PAGE>
This Post-Effective Amendment to the Registration Statement on
Form S-6 comprises the following papers and documents:
The facing sheet on Form S-6.
The Prospectus.
Signatures.
Consent of independent public accountants and consent of
evaluator; all other consents were previously filed.
The following Exhibits:
****EX-3.(i) - Restated Certificate of Incorporation of Prudential
Securities Incorporated dated March 29, 1993.
*****EX-3.(ii) - Revised By-Laws of Prudential Securities
Incorporated as amended through June 21, 1996.
+EX-4 - Trust Indenture and Agreement dated September 6,
1989.
*EX-23 - Consent of Kenny S&P Evaluation Services, a
division of J.J. Kenny Co., Inc. (as evaluator).
***EX-24 - Powers of Attorney executed by a majority of the
Board of Directors of Prudential Securities
Incorporated.
*Ex-27 - Financial Data Schedule.
Ex-99 - Information as to Officers and Directors of
Prudential Securities Incorporated is
incorporated by reference to Schedules A and D of
Form BD filed by Prudential Securities
Incorporated pursuant to Rules l5b1-1 and l5b3-1
under the Securities Exchange Act of 1934 (1934
Act File No. 8-16267).
**EX-99.2 - Affiliations of Sponsor with other investment
companies.
**EX-99.3 - Broker's Blanket Policies, Standard Form No. 39 in
the aggregate amount of $62,500,000.
+EX-99.4 - Investment Advisory Agreement.
II-1
<PAGE>
_________________________
* Filed herewith.
** Incorporated by reference to exhibit of same designation filed with
the Securities and Exchange Commission as an exhibit to the
Registration Statement under the Securities Act of 1933 of Prudential
Unit Trusts, Insured Tax-Exempt Series 1, Registration No. 2-89263.
*** Incorporated by reference to exhibits of same designation filed with
the Securities and Exchange Commission as an exhibit to the
Registration Statement under the Securities Act of 1933 of National
Municipal Trust Series, Series 172, Registration No. 33-54681 and
National Equity Trust, Top Ten Portfolio Series 3, Registration No.
333-15919.
**** Incorporated by reference to exhibit of same designation filed with
the Securities and Exchange Commission as an exhibit to the
Registration Statement under the Securities Act of 1933 of Government
Securities Equity Trust Series 5, Registration No. 33-57992.
***** Incorporated by reference to exhibit of same designation filed with
the Securities and Exchange Commission as an exhibit to the
Registration Statement under the Securities Act of 1933 of National
Municipal Trust, Series 186, Registration No. 33-54697.
+ Incorporated by reference to exhibit of same designation filed with
the Securities and Exchange Commission as an exhibit to the
Registration Statement under the Securities Act of 1933 of National
Municipal Trust, Insured Series 43, Registration No. 33-29314.
II-2
<PAGE>
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933, the
registrant, National Municipal Trust, Series 173 certifies that it meets
all of the requirements for effectiveness of this Registration Statement
pursuant to Rule 485(b) under the Securities Act of 1933 and has duly
caused this Registration Statement or amendment thereto to be signed on its
behalf by the undersigned thereunto duly authorized, in the City of New
York, and State of New York on the 16th day of April, 1997.
NATIONAL MUNICIPAL TRUST,
Series 173
(Registrant)
By PRUDENTIAL SECURITIES INCORPORATED
(Depositor)
By the following persons,* who
constitute a majority of the
Board of Directors of Prudential
Securities Incorporated
Robert C. Golden
Alan D. Hogan
A. Laurence Norton, Jr.
Leland B. Paton
Martin Pfinsgraff
Vincent T. Pica II
Hardwick Simmons
Lee B. Spencer, Jr.
By /s/ Kenneth Swankie
-----------------------------
(Kenneth Swankie
Senior Vice President,
Manager--Unit Investment
Trust Department,
as authorized signatory for
Prudential Securities
Incorporated and Attorney-
in-Fact for the persons
listed above)
_____________________
* Pursuant to Powers of Attorney previously filed.
II-3
<PAGE>
CONSENT OF COUNSEL
The consent of counsel to the use of its name in the Prospectus
included in this Registration Statement is contained in its opinion filed
as Exhibit 5 to the Registration Statement.
II-4
<PAGE>
CONSENT OF INDEPENDENT AUDITORS
We consent to the use of our report dated April 1, 1997, accompanying the
financial statements of the National Municipal Trust Series 173 included
herein and to the reference to our Firm as experts under the heading
"Auditors" in the prospectus which is a part of this registration statement.
DELOITTE & TOUCHE LLP
DELOITTE & TOUCHE LLP
April 15, 1997
New York, New York
II-5
<PAGE>
Exhibit 23
Letterhead of Kenny S&P Evaluation Services
(a division of J.J. Kenny Co., Inc.)
April 17, 1997
Prudential Securities Incorporated
1 New York Plaza
New York, NY 10292
Re: National Municipal Trust
Post-Effective Amendment No. 2
Series 173
Gentlemen:
We have examined the post-effective Amendment to the
Registration Statement File No. 33-55833 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 references
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 as
of the date of the evaluation report.
You are hereby authorized to file a copy of this letter with
the Securities and Exchange Commission.
Sincerely,
Frank A. Ciccotto
Frank A. Ciccotto
Vice President
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND> THE SCHEDULE CONTAINS SUMMARY FINANCIAL
INFORMATION EXTRACTED FROM THE FINANCIAL
STATEMENTS FOR NATIONAL MUNICIPAL TRUST
SERIES 173 AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL
STATEMENTS
</LEGEND>
<RESTATED>
<CIK> 0000924429
<NAME> NATIONAL MUNICIPAL TRUST
SERIES 173
<SERIES>
<NAME> NATIONAL MUNICIPAL TRUST
SERIES 173
<NUMBER> 1
<MULTIPLIER> 1
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> Dec-31-1996
<PERIOD-START> Jan-1-1996
<PERIOD-END> Dec-31-1996
<INVESTMENTS-AT-COST> 9,285,804
<INVESTMENTS-AT-VALUE> 10,077,291
<RECEIVABLES> 227,318
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 10,304,609
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 195,341
<TOTAL-LIABILITIES> 195,341
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 9,285,804
<SHARES-COMMON-STOCK> 10,000
<SHARES-COMMON-PRIOR> 10,000
<ACCUMULATED-NII-CURRENT> 31,977
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 791,487
<NET-ASSETS> 10,109,268
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 651,662
<OTHER-INCOME> 2,834
<EXPENSES-NET> 22,207
<NET-INVESTMENT-INCOME> 632,289
<REALIZED-GAINS-CURRENT> 3,776
<APPREC-INCREASE-CURRENT> (71,379)
<NET-CHANGE-FROM-OPS> 564,686
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 633,000
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 185,000
<NUMBER-OF-SHARES-SOLD> 0
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (253,314)
<ACCUMULATED-NII-PRIOR> 35,522
<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> 0
<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>
