ACORN INVESTMENT TRUST
497, 1997-08-26
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<PAGE>
 


                               [PHOTO OF ACORNS]



                                        prospectus

                                             1997



                                             -------------------------
                                             The Acorn Family of Funds

                                             Prospectus and Application

                                             April 30, 1997





Managed by Wanger Asset Management, L.P.

<PAGE>
 
Dear Investor: 
    

Thank you for your interest in the Acorn Family of Funds. This prospectus
outlines the funds' policies and procedures, and contains quick-reference pages
for buying or selling shares, fund contacts and more on pages 38-43. Please
take the time to read it carefully.

The Acorn funds are growth funds managed by Wanger Asset Management, L.P. The
flagship, Acorn Fund, is a global fund investing in small to mid-size companies
in the U.S. and abroad, and has helped investors reach their long-term goals for
more than 26 years. Acorn International, the second fund in the series, invests
in small to mid-size companies in about 40 markets overseas. The newest fund,
Acorn USA, was launched in September 1996, and invests in small to mid-size
companies in the U.S. With the Acorn Family of Funds, investors have the
flexibility to balance their weightings of domestic and foreign stocks. Whether
you invest in one or all of our funds, each fund is highly diversified, helping
to reduce return volatility.

At Wanger Asset Management, L.P. (WAM), we employ a team investment approach.
The investment team is comprised of the lead portfolio manager, co-portfolio
managers, and research analysts. Team members share responsibility for providing
ideas, information, and knowledge in managing each of the Acorn funds. We are
very proud of our outstanding investment team, which has over 130 years of
combined investment experience. We invite you to learn more about some of our
distinguished team members on pages 24-25.

Investing with the Acorn funds helps you save money. How? All three funds
are 100% no-load, which means that all of your money goes to work for you
immediately. There are no sales charges, 12b-1 fees or back-end load fees, so
all of your dollars are invested at net asset value.

Providing quality service is a source of pride for us. We strive daily to make
doing business with the Acorn funds as trouble-free as possible. We hope you'll
find our fund literature and account forms easy to understand and complete. If
you ever need help or have any questions, a friendly shareholder services
representative can help. Simply call our toll-free number, 1-800-9-ACORN-9 (1-
800-922-6769) during regular business hours.     

We invite you to squirrel away your acorns for a day when you really need
them, and we look forward to a long and mutually rewarding relationship with
you.

Happy investing,

[sig logo]
Ralph Wanger
President

(Not part of the prospectus.)
<PAGE>
 
Please read this prospectus before investing, and keep it on file for future
reference. It contains important information, including how the funds invest
and the services available to shareholders. 
    
A Statement of Additional Information ("SAI") dated April 30, 1997 has 
been filed with the Securities and Exchange Commission ("SEC"), and is
incorporated herein by reference (is legally considered a part of this
prospectus). The SAI is available free upon request by calling Acorn at 
1-800-9-ACORN-9 (1-800-922-6769).

You may also obtain the SAI, as well as other information that has been
electronically filed, from the SEC's web site (www.sec.gov).

Acorn Fund, Acorn International and Acorn USA invest for long-term capital
growth. Each fund invests mostly in stocks of small and medium-size companies.
Acorn Fund invests mostly in U.S. companies, but also has significant foreign
investments. Acorn International invests in overseas companies. Acorn USA
invests in U.S. companies.

 .LIKE ALL MUTUAL FUNDS, 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.

The Acorn Family of Funds
 . Acorn Fund
 . Acorn International
 . Acorn USA

No-Load Funds

Prospectus and Application
April 30, 1997     

Acorn Investment Trust 227 West Monroe Street Suite 3000 Chicago, Illinois
60606 
<PAGE>
 
<TABLE> 

Contents

<S>     <C>                                        <C> 
The Funds at a Glance                               3
        .Goal           
        .Strategy               
        .Management             
        .Who May Want to Invest                     4

Expenses and Performance                            5       
        .Expenses
        .Financial History                          6
        .Performance                               10

Your Account                                       11      
        .Doing Business with Acorn
        .How to Buy Shares
        .How to Sell Shares                        12
        .Selling Shares in Writing
        .Redemption Price                          13

Choices for Your Account        
Registration                                       14

Shareholder and Account 
Policies                                           16
        .Statements and Reports
        .Share Price
        .Purchases      
        .Redemptions                               18
        .Address Changes
        .Telephone Transactions                    19   
        .Telephone Exchange Plan                   20
        .Exchange Plan Restrictions     


Dividends, Capital Gains,       
and Taxes                                          22
        .Distribution Options
        .Taxes
        .Foreign Income Taxes                      23

Meet the Team                                      24      

The Funds in Detail                                26 
        .Organization    
        .Management     
        .Distributor                               27           
        .Expenses                                  28  
        .The Acorn Philosophy        
        .Securities, Investment 
        Practices, and Risks                       30
        .Foreign Securities                        31
        .Managing Investment 
        Exposure                                   32
        .Illiquid and Restricted 
        Securities                                 35
        .Diversification      
        .Other Investment 
        Companies               
        .Lending and Repurchase 
        Agreements                                 36
                
Highlights                                         37 
        .Doing Business with Acorn
        .How to Buy Shares                         38  
        .How to Sell Shares                        40 
        .How to Contact Us                         42      
</TABLE>

                                       2
<PAGE>
 
Acorn Family of Funds
   .At a Glance


Goal

Acorn Fund, Acorn International and Acorn USA invest for long-term growth of
capital. 


Strategy

The Acorn funds are small to mid-cap growth funds. The funds look for
attractively-priced companies that Wanger Asset Management, investment advisor
to the funds, thinks will benefit from favorable long-term social, economic, or
political trends. The areas of emphasis may change from time to time. Acorn
Fund is a global fund investing in the U.S. and abroad. Acorn International
concentrates its investments in overseas companies, while Acorn USA invests in
U.S. companies.


Management

Wanger Asset Management, L.P. (WAM) employs a team approach to management of the
funds. The management team is comprised of the lead portfolio manager, other WAM
portfolio managers and research analysts. Each team member has one or more areas
of expertise, and shares responsibility for providing ideas, information, and
knowledge in managing the funds. Daily decisions on portfolio selection rest
with the lead portfolio manager who utilizes the input and advice of the
management team in making purchase and sale determinations. Ralph Wanger is the
lead portfolio manager, and Charles P. McQuaid and Terence M. Hogan are the co-
portfolio managers of Acorn Fund. Leah J. Zell is the lead portfolio manager of
Acorn International and Robert A. Mohn is the lead portfolio manager of Acorn
USA.     
               
                                       3
<PAGE>
 
 .At a Glance, continued

    
Who May Want to Invest 

The Acorn funds are designed for investors who want long-term growth of capital
rather than income and who have the long-term investment outlook needed for
investing in the stocks of small and medium-size companies in the U.S. and
overseas. The return generated by each fund's portfolio securities varies from
day to day. Performance depends on WAM's skills in identifying the trends that
are the basis for the funds' stock selections, and in picking individual stocks,
as well as general market and economic conditions. When you sell your shares,
they may be worth more or less than you paid for them. The stocks of smaller
companies often involve more risk than the stocks of larger companies. Over
time, stocks have shown greater growth potential than other types of securities.
In the short term, however, stock prices may fluctuate widely in response to
company, market, or economic news. The funds are not by themselves a balanced
investment plan.

To invest you must be a U.S. citizen (or a non-citizen residing in the U.S.)
with a social security or tax identification number.

See "Your Account" for how to buy and redeem shares.

        Did You 
                Know?

The Funds' 16 member investment team reflects four different nationalities and
18 graduate degrees, including two Ph.D's, a CPA, a statistician, and an
attorney.     

                                       4
<PAGE>
 
 .Expenses and Performance 

Expenses

Shareholder transaction expenses are charges you pay when you buy or sell
shares of a fund. 

Transaction Expenses
- ---------------------------------------------
Maximum sales charge on purchases 
and reinvested dividends                None
Deferred sales charge on redemptions    None
Exchange fee                            None
Wire transaction fee                    None

Annual fund operating expenses. Each fund pays its own operating expenses,
including the management fee to WAM. Expenses are factored into a fund's 
price or dividends, and are subtracted from the share price daily. They are
not charged directly to shareholder accounts. 

The following are projections based on historical expenses for Acorn Fund
and Acorn International; expenses for Acorn USA are estimated. All expenses are
calculated as a percentage of average net assets. 

Acorn Fund
- ---------------------------------------------
Management fee                  .46%
12b-1 fee                      None
Other expenses                  .11%
                               ----
Total fund operating expenses   .57%

Acorn International
- ---------------------------------------------
Management fee                  .85%
12b-1 fee                      None
Other expenses                  .32%
                               ----
Total fund operating expenses  1.17%

Acorn USA
- ---------------------------------------------
Management fee                 1.00%
12b-1 fee                      None
Other expenses (estimated)      .85%
                               ----
Total fund operating expenses  1.85%

 .Example: Let's say, hypothetically, that each fund's annual return is 5%
and that its operating expenses are exactly as shown above and to the left. For
every $1,000 you invested, here's how much you would have paid in total
expenses if you closed your account after the number of years indicated: 

Acorn Fund
- ---------------------------------------------
After 1 year                   $  6
After 3 years                  $ 18
After 5 years                  $ 32
After 10 years                 $ 71

Acorn International
- ---------------------------------------------
After 1 year                   $ 12
After 3 years                  $ 37
After 5 years                  $ 64
After 10 years                 $142

Acorn USA
- ---------------------------------------------
After 1 year                   $ 19
After 3 years                  $ 58

These examples illustrate the effect of expenses, but are not meant to
suggest actual or expected costs or returns, all of which may vary.     

                                       5
<PAGE>
 
 .Expenses and Performance
    

Financial History

The financial history of each fund has been audited by Ernst & Young LLP,
independent auditors. Their unqualified report is included in Acorn's Annual
Report. The financial statements of each fund and the auditors' report are
incorporated by reference into the SAI.

<TABLE> 
<CAPTION> 

Acorn Fund                                                  Years ended 12/31,
- --------------------------------------------------------------------------------
For a share outstanding throughout each year                  1996      1995
<S>                                                         <C>       <C> 
Net Asset Value, beginning of year                          $13.60    $12.24    
Income From Investment Operations
    Net investment income                                      .09       .11
    Net gain (loss) on investments, foreign currency and 
      futures (both realized and unrealized)                  2.93      2.42
- --------------------------------------------------------------------------------
    Total from investment operations                          3.02      2.53
Less Distributions
    Dividends from net investment income                      (.11)     (.09)
    Distributions from net realized and unrealized gains
     reportable for federal income taxes                     (1.47)    (1.08)
- --------------------------------------------------------------------------------
    Total distributions                                      (1.58)    (1.17)
- --------------------------------------------------------------------------------
Net Asset Value, end of year                                $15.04    $13.60
- --------------------------------------------------------------------------------
Total Return                                                  22.6%     20.8%
Ratios/Supplemental Data
    Ratio of expenses to average net assets                    .57%      .57%
    Ratio of net investment income to average net assets       .53%      .89% 
    Portfolio turnover rate                                     33%       29%
    Net assets at end of year (in millions)                 $2,842    $2,399

</TABLE> 

The average commission rate paid per share by Acorn Fund on stock transactions
during 1996 was $.0194.


Financial Highlights Terms

Net Asset Value ("NAV") is the value of a single share of a fund. It is computed
by adding the value of all of a fund's investments, cash and other assets,
subtracting any liabilities and dividing the result by the number of shares
outstanding.

Net Investment Income (loss) is the per share amount of dividends, interest, and
other income earned on securities held by a fund, less fund expenses.

Net gain (loss) on investments, foreign currency and futures is the per share
increase or decrease in value of the securities, foreign currencies and futures
a fund holds. A gain (loss) is realized when securities, foreign currencies
and/or futures are sold. A gain (loss) is unrealized when securities, foreign
currencies and/or futures increase or decrease in value but are not sold.

Dividends from net investment income are the per share amount that a fund paid
to shareholders from net investment income.

Distributions from net realized and unrealized gains are the per share amount
that a fund paid to shareholders from net realized gains on investments and any
unrealized gains, resulting from holding passive foreign investment companies
("pfics").     


                                       6

<PAGE>
 
<TABLE>
<CAPTION>
- ------------------------------------------------------------------------------- 
     1994      1993      1992      1991      1990     1989     1988      1987
   <S>       <C>       <C>       <C>       <C>       <C>      <C>      <C> 
   $13.95    $11.06    $ 9.32    $ 6.51    $ 8.58    $7.27    $6.48    $ 7.45
      
      .06       .04       .07       .11       .12      .13      .12       .14

    (1.10)     3.50      2.16      2.95     (1.62)    1.65     1.47       .12
- ------------------------------------------------------------------------------- 
    (1.04)     3.54      2.23      3.06     (1.50)    1.78     1.59       .26

     (.11)     (.06)     (.08)     (.10)     (.13)    (.11)    (.16)     (.15)
 
     (.56)     (.59)     (.41)     (.15)     (.44)    (.36)    (.64)    (1.08)
- ------------------------------------------------------------------------------- 
     (.67)     (.65)     (.49)     (.25)     (.57)    (.47)    (.80)    (1.23)
- ------------------------------------------------------------------------------- 
   $12.24    $13.95    $11.06    $ 9.32    $ 6.51    $8.58    $7.27    $ 6.48
- ------------------------------------------------------------------------------- 
     (7.4%)    32.3%     24.2%     47.3%    (17.5%)   24.8%    24.8%      4.4%

      .62%      .65%      .67%      .72%      .82%     .73%     .80%      .82%
      .55%      .30%      .72%     1.30%     1.60%    1.59%    1.52%     1.85%
       18%       20%       25%       25%       36%      26%      36%       52%
   $1,983    $2,035    $1,449    $1,150    $  767    $ 855    $ 563    $  418
</TABLE> 

Total Return is the percentage increase or decrease in the value of an
investment over a stated period of time. Total Return includes both changes in
NAV and income. For the purpose of calculating Total Return, it is assumed that
dividends and distributions are reinvested at the NAV on the day after the
record date.

Ratio of expenses to average net assets is the total of a fund's operating
expenses divided by its average net assets for the stated period. It does not
reflect reductions in expenses through uninvested cash balances earning interest
with a fund's custodian.

Ratio of net investment income (loss) to average net assets is a fund's net
investment income divided by its average net assets for the stated period.

Portfolio turnover rate is a measure of the amount of a fund's buying and
selling activity. It is computed by dividing total purchases or sales, whichever
is less, by the average monthly market value of a fund's portfolio securities.
     

                                       7

<PAGE>
 

<TABLE> 
<CAPTION> 
     
Expenses and Performance, continued

Acorn International                                           Years ended 12/31,
- -------------------------------------------------------------------------------
<S>                                                            <C>       <C>
For a share outstanding throughout each period                   1996      1995

Net Asset Value, beginning of period                           $16.59    $15.24

Income From Investment Operations
  Net investment income (loss)                                    .13       .16
  Net gain (loss) on investments and foreign currency
     (both realized and unrealized)                              3.29      1.20
- -------------------------------------------------------------------------------
  Total from investment operations                               3.42      1.36

Less Distributions
  Dividends from net investment income                           (.12)       --
  Distributions from net realized and unrealized gains
     reportable for federal income taxes                         (.28)     (.01)
- -------------------------------------------------------------------------------
  Total distributions                                            (.40)     (.01)
- -------------------------------------------------------------------------------
Net Asset Value, end of period                                 $19.61    $16.59
===============================================================================
Total Return                                                    20.7%      8.9%

Ratios/Supplemental Data
  Ratio of expenses to average net assets                       1.17%     1.22%
  Ratio of net investment income (loss) to average net assets    .51%      .90%
  Portfolio turnover rate                                         34%       26%
  Net assets at end of period (in millions)                    $1,773    $1,276


                                                            Inception 9/4
Acorn USA                                                   through 12/31,
- -------------------------------------------------------------------------------
For a share outstanding throughout each period                   1996

Net Asset Value, beginning of period                           $10.00

Income From Investment Operations
  Net investment loss                                            (.02)
  Net gain (loss) on investments
     (both realized and unrealized)                              1.67
- -------------------------------------------------------------------------------
  Total from investment operations                               1.65
- -------------------------------------------------------------------------------
Net Asset Value, end of period                                 $11.65
===============================================================================
Total Return                                                    16.5%

Ratios/Supplemental Data
  Ratio of expenses to average net assets**                     1.85% *
  Ratio of net investment loss to average net assets            (.99%)*
  Portfolio turnover rate                                         20% *
  Net assets at end of period (in millions)                       $53     

</TABLE>
                                       8
<PAGE>
 
<TABLE> 
<CAPTION> 
     
                   Inception
                        9/23
                     through
                      12/31,
- ----------------------------
<S>       <C>         <C>
  1994      1993        1992
$15.94   $ 10.69     $ 10.00

   .07       .00        (.03)

  (.67)     5.25         .72
- ----------------------------
  (.60)     5.25         .69

    --        --          --

  (.10)       --          --
- ----------------------------
  (.10)       --          --
- ----------------------------
$15.24   $ 15.94     $ 10.69
============================
 (3.8%)    49.1%        6.9%

 1.24%     1.21%      2.35%*
  .48%      .06%    (1.37%)*
   20%       19%        20%*
$1,363   $   907     $    30
</TABLE> 


*  Annualized

** The ratio of expenses to average net assets for Acorn USA reflects gross
   custodian fees. This ratio net of custodian fees paid indirectly would have
   been 1.79%.

   The average commission rate paid per share by Acorn International on stock
   transactions during 1996 was $.0008; for Acorn USA, it was $.0567.     

                                       9
<PAGE>
 
 . Expenses and Performance, continued


Performance

Mutual fund performance is commonly measured as total return. Total return is
the change in value of an investment in a fund over a given period, assuming
reinvestment of any dividends and capital gains. Total return reflects actual
performance over a stated period of time. Average annual total return is a
hypothetical rate of return that, if achieved annually, would have produced the
same total return if performance had been constant over the entire period.
Average annual total returns smooth out variations in performance; they are not
the same as actual year-by-year results.

Total returns are based on past results and are not a prediction of future
performance. They do not include the effect of income taxes.

The funds sometimes show their performance compared to stock indexes (described
in the SAI [Statement of Additional Information]), or give their ratings or
rankings determined by an unrelated organization. 

Information about the performance of the funds is contained in Acorn's Annual
Report which may be obtained free of charge by calling the Acorn funds at 
1-800-9-ACORN-9 (1-800-922-6769).




        No-Load
- --------------------------------------------------------------------------------
                Advantage

Acorn Fund, Acorn International and Acorn USA are 100% no-load, which means that
all of your money goes to work for you immediately. There are no sales charges,
12b-1 fees or back-end load fees, so all of your dollars are invested at net
asset value. The Acorn funds invest in companies for the long-term (usually 2-5
years), so our turnover rate is low. This minimizes both trading costs and
shareholders' taxes. All these factors add up to greater value for our
shareholders.
     
                                       10
<PAGE>
 
 . Your Account


Doing Business with Acorn 

Acorn provides customers with service Monday through Friday, except holidays,
from 8:00 a.m. to 4:30 p.m. Central time.

To reach Acorn, call: 

 . For fund information, prices, or literature--1-800-9-ACORN-9 (1-800-922-6769)
  (from outside the U.S. 1-312-634-9240)

 . To add to your existing account, redeem shares, or exchange shares by
  telephone--call our transfer agent by 3:00 p.m. Central time at 1-800-962-1585
  (outside the U.S. 1-617-774-5000 ext. 6457) 

 . For help in setting up your account or for IRA assistance--call our transfer
  agent at 1-800-962-1585 (outside the U.S. 1-617-774-5000 ext. 6457)

 . For 24-hour account balances, 7 days a week -- 1-800-962-1585. 

How to Buy Shares
You can open a new account by: 
 
 . mailing in an application with your check or money order payable to Acorn
  Fund, Acorn International or Acorn USA for $1,000 or more (the Acorn funds do
  not accept third party checks), or

 . using the exchange plan to move $1,000 or more from an account with Acorn
  Fund, Acorn International, Acorn USA or one of the Reich & Tang Funds into a
  new identically-registered account within the Acorn family.
 
 . wire-call 1-800-962-1585 to set up your account and to arrange a wire
  transaction. Not available for IRA accounts.

After your account is open, you may add to it by: 

 . wiring money from your bank; 

 . moving money from your bank account by telephone if you participate in the
  telephone purchase plan;

 . using the telephone exchange plan to move your investment from one Acorn fund
  to another, or from one of the Reich & Tang Funds; or

 . mailing your check or money order payable to Acorn Fund, Acorn International
  or Acorn USA for $100 or more with the stub from one of your account
  statements, with a slip from the investment booklet provided by Acorn or with
  a letter of instruction. (The Acorn funds do not accept third party checks.)

You must make your telephone purchases or exchanges from the Acorn funds by 3:00
p.m. Central time. To exchange out of the Reich & Tang Funds, you must call by
11:00 a.m. Central time. See "Telephone Exchange Plan."

Your wire purchase money and your application must both be received by Acorn's
transfer agent by Closing Time (usually 3:00 p.m. Central time) for you to
receive that day's price. If the proceeds of your wire order are received, but
your application has not been received by the transfer agent, you will receive
the price for the day on which your application is received by the transfer
agent. Your application must be received no later than 12:00 p.m. Central time
the day after your wire is received, or your wire will be returned to you.
     
                                      11
<PAGE>
 
 .Your Account, continued


See "Shareholder and Account Policies" for more exchange plan information. 

If you are investing through an Acorn IRA or SIMPLE IRA for the first time
you will need a special application. Call 1-800-962-1585. For both initial and
subsequent IRA investments, please indicate the year for which the investment is
being made.

Minimum Investments
- -------------------------------------
To open an account             $1,000
To open an IRA                 $1,000
To add to an account           $  100

If you sign up for the Automatic Investment Plan and later wish to change the
amount or frequency of your automatic investments, or stop future investments,
you may do so by simply calling us at 1-800-962-1585 at least one week prior to
your next scheduled investment date.

How to Sell Shares 

You can arrange to take money out of your fund account at any time by selling
(redeeming) some or all of your shares. Your shares will be sold at the next NAV
(share price) calculated after your order is received and accepted. See
"Shareholder and Account Policies" for more information about share price. To
sell shares in a regular (non-IRA) account, you may use any of the methods
described here. To sell shares in an Acorn IRA, your request must be made in
writing, except for exchanges between the Acorn funds or to the Reich & Tang
Short Term Income Money Market Portfolio, which can be requested before 3:00
p.m. Central time by calling 1-800-962-1585. If you need an IRA Withdrawal
Request form, call us at 1-800-9-ACORN-9 (1-800-922-6769).

The Telephone Redemption Plan lets you redeem $100 to $50,000 per day by
phone. You must make your telephone redemptions by 3:00 p.m. Central time. You
automatically have the telephone redemption plan unless you decline it on your
application. If you have changed the address on your account by telephone
within 60 days of the telephone redemption request, this service is not
available. Instead, you must send a letter of instruction signature guaranteed
by all account owners. 

The Systematic Withdrawal Plan lets you set up automatic monthly or quarterly
redemptions from your account in specified dollar amounts if you have a $25,000
minimum Acorn account balance. Call 1-800-9-ACORN-9 (1-800-922-6769) for a Doing
Business with Acorn form.

Selling Shares in Writing 

Write a "letter of instruction" with: 

 . your name, 

 . the fund's name, 

 . your fund account number, 

 . the dollar amount or number of shares to be redeemed, 

 . the stock certificates representing your shares to be redeemed, if you
  hold certificates for your shares, and

 . any other applicable requirements listed in the table on pages 40-41.
     

                                       12
<PAGE>
 
Mail your letter to: 

   State Street Bank and Trust Co. 
   Attn: Acorn funds 
   P.O. Box 8502 
   Boston, MA 02266-8502 

If you are using overnight mail: 

   Boston Financial Data Services 
   Attn: Acorn funds 
   2 Heritage Drive, 6th Floor 
   N. Quincy, MA 02171
   1-617-774-5000 ext. 6457 

Do not sign your stock certificates. Send them by registered or certified
mail so that you may receive a confirmation of delivery.

Certain requests must include a signature guarantee, designed to protect you
and Acorn from fraudulent activities. Your request must be made in writing and
include a signature guarantee if any of the following situations applies: 

 . you wish to redeem more than $50,000 worth of shares; 

 . your name has changed by marriage or divorce (send a letter indicating
  your account number(s) and old and new names, signing the letter in both the
  old and new names and having both signatures guaranteed) 

 . your address has changed within the last 60 days and you would like to
  redeem shares; 

 . the check is being mailed to an address different from the one on your
  account (address of record); 

 . the check is being made payable to someone other than the account owner; 

 . you are instructing us to wire the proceeds to a bank or brokerage account
  and have not signed up for the telephone redemption by wire plan. 

You should be able to obtain a signature guarantee from a bank,
broker-dealer, credit union (if authorized under state law), securities
exchange or association, clearing agency, or savings association. A notary
public cannot provide a signature guarantee. 

Redemption Price

The price at which your shares will be redeemed is determined by the time of day
our transfer agent receives your redemption request. The price per share is
always the next net asset value (NAV) per share calculated after your redemption
request, including any required signature guarantee or supporting documents, is
received. The funds calculate the NAV as of Closing Time on each day the New
York Stock Exchange (NYSE) is open for trading.

Closing Time is the close of NYSE regular session trading, which is usually
3:00 p.m. Central time but is sometimes earlier.

To get today's price--

 . Use the telephone redemption plan to call your redemption request in
  before Closing Time (note that the Closing Time to exchange out of the Reich &
  Tang Funds is 11:00 a.m. Central time). 

 . Have your written redemption request, with a signature guarantee, if
  required, and any supporting documents, delivered to our transfer agent before
  Closing Time.      

                                       13
<PAGE>
 
 . Choices for your Account Registration


Individual or Joint Ownership 
- --------------------------------------------------------------------------------
        For your general investment needs 

Individual accounts are owned by one person. Joint accounts can have two or
more owners. 


Gift or Transfer to a Minor (UGMA, UTMA) 
- --------------------------------------------------------------------------------
        To invest for a minor's education or other future needs 

These custodial accounts provide a way to give money to a minor. The account
application must include the minor's social security number.
 

Trust or Established Employee Benefit or Profit-Sharing Plan 
- --------------------------------------------------------------------------------
        For money being invested by a trust, employee benefit plan, or
        profit-sharing plan
 
The trust or plan must be established before an account can be opened. 


Corporation or Other Entity 
- --------------------------------------------------------------------------------
        For investment needs of corporations, associations, partnerships,
        institutions, or other groups 

You will need to send a certified corporate resolution with your application.


Retirement 
- --------------------------------------------------------------------------------
        To shelter your retirement savings from taxes 

Retirement plans allow individuals to shelter investment income and capital
gains from current taxes. Contributions to these accounts may be
tax-deductible. IRAs require a special application (call 1-800-9-ACORN-9).

     . Acorn Individual Retirement Accounts (IRAs) allow anyone of legal age and
       under 70-1/2 with earned income to save up to $2,000 per tax year. If
       your spouse has less than $2,000 in earned income, he or she may still
       contribute up to $2,000 to an IRA, so long as you and your spouse's
       combined earned income is at least $4,000.

     . Rollover IRAs retain special tax advantages for certain distributions
       from employer-sponsored retirement plans.
     
                                       14
<PAGE>
 
 . Simplified Employee Pension Plans (SEP-IRAs) allow small business owners
or those with self-employment income to make tax-deductible contributions of up
to 15% of the first $160,000 of compensation per year for themselves and any
eligible employees. 

 . SIMPLE IRAs must be established by an employer (including a self-employed
person), and enable all employees of the employer to elect to have up to $6,000
per year deducted from their paychecks on a before-tax basis and deposited
directly into an account maintained for the individual employee. The employer
is also generally required to make a contribution for each employee who elects
to contribute. SIMPLE IRAs require a special application (call 1-800-962-1585).

 . Other retirement plans--The fund may be used as an investment in other
kinds of retirement plans, including Keogh or corporate profit-sharing and
money purchase plans, 403(b) plans, and 401(k) plans. All of these accounts
need to be established by the trustee of the plan. Acorn does not offer
prototypes of these plans. 



                                    Acorn 
 -------------------------------------------------------------------------------
                                              facts

 . Acorn Fund commenced operations in 1970; Acorn International opened to
  investors in 1992, followed by Acorn USA in 1996.

 . Number of shareholder accounts: more than 140,000

 . Number of portfolio managers and analysts working for the funds: 16

 . Wanger Asset Management, the advisor to the Acorn funds, specializes in
  finding small, niche companies for shareholders.      

                                       15
<PAGE>
 
 Shareholder and Account Policies 


Statements and Reports 
Statements and reports that Acorn sends to you include: 

  Confirmation statements (after every transaction in your account or change
  in your account registration) 

  Quarterly and year-end account statements 

  Shareholder reports 
     
If you would like us to send duplicate statements to someone, simply call us
at 1-800-962-1585, and we can take your request over the telephone. Average
cost statements for shares redeemed are available upon request for most
accounts.

If you need copies of your historical account information, please call 
1-800-962-1585. There is a small charge for historical account information
for prior years. 
    
Share Price
The funds are open for business each day the New York Stock Exchange (NYSE)
is open. The offering price (price to buy one share) and redemption price
(price to sell one share) are the fund's net asset value ("NAV") calculated at
the next Closing Time after receipt of your order. Closing Time is the time of
the close of regular session trading on the NYSE, which is usually 3:00 p.m.
Central time but is sometimes earlier.      

A fund's NAV is the value of a single share. The NAV is computed by adding
up the value of the fund's investments, cash, and other assets, subtracting its
liabilities, and then dividing the result by the number of shares outstanding. 

Each fund's portfolio securities and assets are valued primarily on the
basis of market quotations from the primary market in which they are traded or,
if quotations are not readily available, by a method that the board of trustees
believes accurately reflects a fair value. Values of foreign securities are
translated from the local currency into U.S. dollars using current exchange
rates.
    
Your purchase or redemption of fund shares will be priced at the next NAV
calculated after your investment (including the application, if for a new
account, and the money) or redemption request is received and accepted by
Acorn's transfer agent, or by certain other agents and dealers authorized to
accept purchase and redemption requests on Acorn's behalf. An order received
before Closing Time will get that day's price. No telephone orders will be
accepted after Closing Time. 

Purchases
  All of your purchases must be made in U.S. dollars and checks must be drawn on
  U.S. banks. The Acorn funds do not accept third party checks.

  Acorn does not accept cash or credit cards. 
     

                                       16
<PAGE>
 
 . If payment for your check or telephone purchase order does not clear, your
  purchase will be canceled and you will be liable for any losses or fees the
  fund or its transfer agent incurs.

 . Your Automatic Investment Plan and Telephone Purchase Plan may be immediately
  terminated in the event that any item is unpaid by your financial institution.

 . When you make a purchase by telephone, the money is ordinarily drawn from your
  bank account the day after you call. The Acorn shares are purchased at the NAV
  calculated the day after you call.

Each fund reserves the right to reject any specific purchase order,
including certain purchases through the exchange plan. See "Exchange Plan
Restrictions." Purchases may be refused if, in WAM's opinion, they are of a
size that would disrupt management of the fund. 

You may purchase or redeem shares of the funds through investment dealers,
banks, or other financial institutions. Certain financial institutions that
have entered into sales agreements with the Acorn funds may enter confirmed
purchase orders or redemption requests on behalf of customers on an expedited
basis, including orders by phone, with payment to follow no later than the time
when the fund is priced on the following business day. If payment is not
received by that time, the financial institution could be held liable for
resulting fees or losses. These institutions may charge for their services or
place limitations on the extent to which you may use the services offered by
Acorn. Any such charges could constitute a substantial portion of a smaller
account and may not be in your best interest. There are no charges or
limitations imposed by Acorn other than those described in this prospectus if
shares are purchased (or redeemed) directly from Acorn.

Shares of one or more of the Acorn funds may be purchased through certain
financial service companies, without incurring any transaction fee. In
addition, certain financial institutions that have entered into agreements with
Acorn act as Acorn's agent for the limited purpose of receiving purchase,
redemption and exchange requests from their clients on behalf of whom the
institution holds shares of one or more of the Acorn funds. Some financial
institutions that act as Acorn's agent for those purposes or that otherwise
maintain nominee accounts with one of the Acorn funds for their clients for
whom they hold fund shares charge an annual fee of up to 0.35% of the average
net assets held in such accounts for accounting, shareholder servicing, and
distribution services the institution provides with respect to the underlying
fund shares. WAM pays any such fees.       

                                       17
<PAGE>
 
 .Shareholder and Account Policies, continued


Redemptions 
 . Normally, redemption proceeds will be mailed within seven days after State
  Street Bank receives a request for redemption. 
    
 . Redemption checks are made payable to the record shareholder or shareholders;
  if you wish for the check to be made payable to someone other than the account
  owners, you must submit your request in writing, and the signatures of all
  record shareholders must be guaranteed. See "Selling Shares in Writing."      

 . A fund may hold payment on redemptions until it is reasonably satisfied that
  it has received payment for a recent purchase made by check, by the Automatic
  Investment Plan, or by the Telephone Purchase Plan, which can take up to
  fifteen days.

 . If you elected to participate in the Telephone Redemption by Wire Plan, Acorn
  will send payment for your redemption to your bank account by wire transfer.
  Your bank may impose a fee for the incoming wire. Payment by wire is usually
  credited to your bank account on the next business day after your call.

 . Redemptions may be suspended or payment dates postponed on days when the NYSE
  is closed (other than weekends or holidays), when trading on the NYSE is
  restricted, or as permitted by the SEC.

 . Certain accounts (such as trust accounts, corporate accounts and custodial
  accounts) may require documentation in addition to the redemption request.
  Call 1-800-962-1585 for more information.

If the value of your account falls below $1,000, Acorn reserves the right to
close your account and send the proceeds to you. Your shares will be redeemed
at the NAV calculated on the day your account is closed. 

If checks representing (1) redemption proceeds, (2) withdrawals under a
systematic withdrawal plan, or (3) dividend and capital gains distributions are
returned "undeliverable" or remain uncashed for six months, the checks will be
canceled and the proceeds will be reinvested in the fund issuing the check at
NAV on the date of cancellation. In addition, after such six-month period, (1)
your systematic withdrawal plan will automatically be canceled and future
withdrawals will occur only when requested, or (2) your cash election will
automatically be changed and future dividends and distributions will be
reinvested in your fund. 

Address Changes
You may change your address over a recorded line by calling 1-800-962-1585.
Acorn will send a written confirmation of the change to both your old and new
addresses. No telephone redemptions may be made for 60 days after a change of
address by phone. During those

                                       18
<PAGE>
 
60 days, a signature guarantee will be required for any written redemption
request unless your change of address was made in writing with a signature
guarantee.

Telephone Transactions
You may initiate many transactions by telephone.

Transactions over a recorded line:

 . Change your address; 

 . Request duplicate statements to be sent to someone you designate; 

 . Request an average cost statement for shares redeemed (available for most
  accounts); 

 . Request a current account statement; 

 . Purchase shares through the telephone purchase plan (plan must be
  pre-established); 

 . Redeem $50,000 or less and have it wired (bank wire-redemption plan must
  be pre-established; not available for IRA accounts); 

 . Change the frequency or amount, or discontinue the Automatic Investment
  Plan on your account(s); 

 . Add or discontinue the telephone exchange privilege to your account; 

 . Add or discontinue the telephone redemption by check privilege to your
  account; 
    
 . Add automatic exchange (from one Acorn fund to another each month) to your
  account;       

 . Change your distribution option (does not apply to IRA accounts); 

 . Redeem $50,000 or less, with a check mailed to the address of record (does
  not apply to IRA accounts, and your address of record must not have changed
  within the last 60 days); 

 . Exchange money from an individual account to an existing IRA account with
  an identical registration; 
    
 . Exchange money between identically-registered accounts in Acorn Fund, Acorn
  International, Acorn USA or certain Reich & Tang Funds, or exchange money from
  one fund to establish an identically-registered account in another fund; and
                                                                                
 . Change the contribution year on an IRA account to the previous year up
  until April 15 of the following year. 

Acorn will not be responsible for any losses resulting from unauthorized
transactions if it follows reasonable procedures designed to verify the identity
of the caller. Those procedures may include recording the call, requesting
additional information, and sending written confirmation of telephone
transactions.

You should verify the accuracy of telephone transactions immediately upon
receipt of your confirmation statement.

                                       19
<PAGE>
 
 .Shareholder and Account Policies, continued


If you do not want to be able to initiate purchase or redemption
transactions by telephone, decline these privileges on your account application
or call Acorn for instructions at 1-800-962-1585. 

If you are unable to reach Acorn by phone (for example, during periods of
unusual market activity), consider placing your order by mail. 
    
Telephone Exchange Plan 
Acorn's telephone exchange plan permits you to exchange your investment between
one Acorn fund and another, or between an Acorn Fund and one of the money market
mutual funds participating in the plan (Reich & Tang Funds) upon telephone
instructions. The Reich & Tang Funds are: Short Term Income Fund, Money Market
Portfolio; Short Term Income Fund, U.S. Government Portfolio; Daily Tax Free
Income Fund; California Daily Tax Free Income Fund; Connecticut Daily Tax Free
Income Fund; Florida Daily Municipal Income Fund; Michigan Daily Tax Free Income
Fund; New Jersey Daily Municipal Income Fund; New York Daily Tax Free Income
Fund; North Carolina Daily Municipal Income Fund; and Pennsylvania Daily
Municipal Income Fund.

Each of the Reich & Tang Funds is a no-load fund managed by Reich & Tang Asset
Management, L.P. and offers check-writing privileges (for accounts other than
IRAs) in addition to the exchange plan. Only Short Term Income Fund, Money
Market Portfolio is available for IRA accounts.

The price at which shares are exchanged is determined by the time of day we
receive your request. To get today's price: 

 . For an IRA account, call us at 1-800-962-1585 before Closing Time.

 . If you are exchanging from one Acorn fund into another, or into one of the
  Reich & Tang Funds, call us at 1-800-962-1585 before Closing Time.

 . If you are exchanging from one of the Reich & Tang Funds to one of the Acorn
  funds, call Reich & Tang at 1-800-221-3079 before 11:00 a.m. Central time.

Because of the time needed to transfer money between the Acorn funds and the
Reich & Tang Funds, you may not exchange into and out of a Reich & Tang Fund on
the same or successive days; there must be at least one day between exchanges.

Exchange Plan Restrictions
 . Generally, you will be limited to 4 round-trip exchanges per year (a round-
  trip being the exchange out of one fund into another fund, and then back
  again).

 . The fund you are exchanging into must be qualified for sale in your state. 
                                                                                
                                       20
<PAGE>
 
 . You may only exchange between accounts that are registered in the same name,
  address, and taxpayer identification number.
    
 . If you are opening a new account by exchange, your exchange must be at least
  $1,000.      

 . The exchange plan is not available for shares of a fund for which you have
  been issued certificates. (If you want to exchange shares between funds, call
  1-800-962-1585 to get instructions for returning your certificates.) 

 . If your account is subject to backup withholding, you may not use the exchange
  plan.

 . Because excessive trading can hurt fund performance and shareholders, the
  funds reserve the right to temporarily or permanently terminate the exchange
  privilege of any investor who makes excessive use of the exchange plan.

 . The funds also reserve the right to refuse exchange purchases by any person or
  group, if Acorn believes the purchase will be harmful to existing
  shareholders.

 . Before exchanging into a fund, you should read its prospectus. 

 . Exchanges may have tax consequences for you. 

The funds reserve the right to terminate or modify the exchange plan at any
time, but will try to give you prior notice whenever they are able to reasonably
do so.

                                       21
<PAGE>
 

 . Dividends, Capital Gains, and Taxes


Each fund distributes substantially all of its net income and capital gains to
shareholders each year. Normally, dividends are paid in July and December, and
capital gains are distributed in December.

Distribution Options 

When you open an account, specify on your application how you would like to
receive your distributions. If you later want to change your distribution
option, call us at 1-800-962-1585. The funds offer three options:

 . Reinvestment Option. Your dividends and capital gain distributions will be
  automatically reinvested in additional shares of the fund. If you do not
  indicate a choice on your application, you will be assigned this option.

 . Income-Only Option. Your capital gain distributions will be automatically
  reinvested, but you will be sent a check for each dividend.

 . Cash Option. You will be sent a check for each dividend and capital gain
  distribution.

For IRA accounts, all distributions are automatically reinvested because payment
of distributions in cash would be a taxable distribution from your IRA, and
might be subject to income tax penalties if you are under 59-1/2 years old.
After you are 59-1/2, you may request payment of distributions in cash.

When you reinvest, the reinvestment price is the fund's NAV at the close of
business on the reinvestment date. The mailing of distribution checks will
usually begin on the payment date, which is usually one week after the ex-
dividend date. The ex-dividend date is the day after the record date.

Taxes 

As with any investment, you should consider how your investment in a fund will
be taxed. If your account is a tax-deferred account (for example, an IRA or an
employee benefit plan account), the following tax discussion does not apply. If
your account is not a tax-deferred account, however, you should be aware of the
following tax rules:

Taxes on distributions. Distributions are subject to federal income tax, and may
also be subject to state or local taxes. If you live outside the United States,
your distributions could also be taxed by the country in which you reside.
 
Your distributions are taxable when they are paid, whether you take them in cash
or reinvest them in additional shares. However, distributions declared in
December and paid in January are taxable as if they were paid on December 31.

For federal tax purposes, each fund's income and short-term capital gain
distributions are taxed as dividends; long-term capital gain distributions are
taxed as long-term capital gains. Every January, Acorn will send you and the IRS
a statement, called a Form 1099-DIV, showing the amount of each taxable
distribution you received in the previous

                                      22
<PAGE>
 
 
year. You may not receive a Form 1099 if total distributions for the year are
less than $10.00. 

Taxes on transactions. Your redemptions--including exchanges between funds or
into a money fund--are subject to capital gains tax. A capital gain or loss is
the difference between the cost of your shares and the price you receive when
you sell them.

Whenever you sell shares of any of the Acorn funds, Acorn will send you a
confirmation statement showing how many shares you sold and at what price. You
will also receive a year-end statement every January. It is up to you or your
tax preparer to determine whether any given sale resulted in a capital gain and,
if so, the amount of tax to be paid. Be sure to keep your regular account
statements; the information they contain will be essential in calculating the
amount of your capital gains.

Foreign Income Taxes

Investment income received by any of the Acorn funds from sources within foreign
countries may be subject to foreign income taxes withheld at the source. If a
fund pays nonrefundable taxes to foreign governments during the year, the taxes
will reduce that fund's dividends but will still be included in your taxable
income. You may be able to claim an offsetting credit or deduction on your tax
return for your share of foreign taxes paid by Acorn International (but not by
Acorn Fund because not enough of Acorn Fund's assets are invested in foreign
securities for Acorn Fund to be able to pass through the foreign tax credit).
Acorn International will send you this information as part of your annual Form
1099-DIV.

When you sign your account application, you will be asked to certify that your
social security or taxpayer identification number is correct and that you are
not subject to 31% backup withholding for failing to report income to the IRS.
If you violate IRS regulations, the IRS can require Acorn to withhold 31% of
your taxable distributions and redemptions.

Understanding
- --------------------------------------------------------------------------------
                                                                   Distributions

As a fund shareholder, you are entitled to your share of a fund's net income and
any net gains realized on its investments.

The funds' income from dividends and interest, and any net realized short-term
capital gain, are paid to you as dividends. A fund realizes capital gains
whenever it sells securities for a higher price than it paid for them. Net
realized long-term gains are paid to you as capital gain distributions.

                                      23
<PAGE>
 
 .Meet the Managers

- --------------------------------------------------------------------------------
Ralph Wanger
president, chief strategist--Acorn Fund, Acorn International and Acorn USA and
lead portfolio manager--Acorn Fund. Mr. Wanger has been involved in managing
each of the Acorn funds since each fund began. Mr. Wanger is president of Acorn
Investment Trust and has been a member of the board of Acorn and its predecessor
since 1970. Mr. Wanger is a principal of Wanger Asset Management, L.P. (WAM). He
is a Chartered Financial Analyst (CFA) and received his B.S. and M.S. degrees in
Industrial Management from the Massachusetts Institute of Technology.
- --------------------------------------------------------------------------------


- --------------------------------------------------------------------------------
Charles P. McQuaid
co-portfolio manager--Acorn Fund. Mr. McQuaid has contributed to Acorn
Fund's growth since 1978. He is senior vice president of Acorn Investment Trust
and a member of its board of trustees. Mr. McQuaid is a principal and the
Director of Research at WAM. A CFA, he earned a B.B.A. from the University of
Massachusetts and M.B.A. from the University of Chicago. Mr. McQuaid focuses on
the areas of communications and media.
- --------------------------------------------------------------------------------


- --------------------------------------------------------------------------------
Terence M. Hogan 
co-portfolio manager--Acorn Fund. Mr. Hogan is a vice president of Acorn
Investment Trust and has been a member of Acorn Fund's management team since
1986. He has been a principal of WAM since 1992. Mr. Hogan is also a CFA, who
earned his degrees from Knox College (B.A.) and the Johnson Graduate School at
Cornell University (M.B.A.). His investment specialization is consumer goods and
services.
- --------------------------------------------------------------------------------
     
                                       24
<PAGE>
 
- --------------------------------------------------------------------------------
Leah J. Zell
lead portfolio manager--Acorn International. Ms. Zell is a vice president of
Acorn who has been working with Acorn Fund's international securities since 1984
and has been a part of Acorn International's management team since it began. Ms.
Zell earned her undergraduate degree from Radcliffe College and holds a Ph.D.
from Harvard University. She is also a Chartered Financial Analyst (CFA). Ms.
Zell visits over 100 companies worldwide each year.
- --------------------------------------------------------------------------------


- --------------------------------------------------------------------------------
Robert A. Mohn
lead portfolio manager--Acorn USA. Mr. Mohn is a vice president of Acorn and
a principal of WAM. In addition to being lead manager of Acorn USA, Mr. Mohn is
also a member of WAM's management team for Acorn Fund, which he joined in 1992.
He is a CFA and received his undergraduate degree from Stanford University and
his M.B.A. from the University of Chicago.
- --------------------------------------------------------------------------------


- --------------------------------------------------------------------------------
Marcel P. Houtzager
investment analyst--Acorn Fund and Acorn International. Mr. Houtzager, a
vice president of Acorn, has been a member of WAM's investment management team
for Acorn Fund and Acorn International since 1992. Mr. Houtzager, who is a
principal of WAM, is a CFA and a Certified Public Accountant. He received his
B.A. from Pomona College and his M.B.A. from the University of California at
Berkeley.
- --------------------------------------------------------------------------------
     
                                       25
<PAGE>
 
 .The Funds in Detail


Organization

Acorn Fund, Acorn International and Acorn USA are series of Acorn Investment
Trust ("Acorn" or the "Trust"), an open-end, management investment company. The
Acorn Fund, Inc. began operations in 1970, and was reorganized as the Acorn
Fund series of the Trust on June 30, 1992. The Trust is a Massachusetts
business trust organized on April 21, 1992. Acorn International began
operations on September 23, 1992. Acorn USA began operations on September 4,
1996.      

Each share of a fund is entitled to participate pro rata in any dividends
and other distributions declared by the board of trustees with respect to that
fund, and all shares of a fund have equal rights in the event of liquidation of
that fund. 

The Trust is governed by a board of trustees, which is responsible for
protecting the interests of the shareholders of the funds. The trustees are
experienced executives and professionals who meet at regular intervals to
oversee the activities of the Trust and the funds. A majority of trustees are
not otherwise affiliated with Acorn or WAM. 

Acorn may hold special meetings of shareholders to elect or remove trustees,
change fundamental policies, approve a management contract, or for other
purposes. Acorn will mail proxy materials in advance, including a voting card
and information about the proposals to be voted on. You are entitled to one vote
for each share of a fund that you own. Shareholders not attending these meetings
are encouraged to vote by proxy.

Management
    
The Acorn funds are managed by Wanger Asset Management, L.P. (WAM), 227 West
Monroe Street, Suite 3000, Chicago, Illinois 60606; WAM chooses the funds'
investments and handles their business affairs, under the direction of the
board of trustees.. WAM is a limited partnership managed by its general
partner, Wanger Asset Management, Ltd., which is controlled by Ralph Wanger.
WAM manages more than $5.6 billion in assets. 

WAM employs a team approach to management of the Acorn funds. The management
teams are comprised of a lead portfolio manager, other WAM portfolio managers
and research analysts. Team members share responsibility for providing ideas,
information and knowledge in managing the funds, with each team member having
one or more particular areas of expertise applicable to the management of the
funds. Daily decisions on portfolio selection rest with the lead portfolio
manager who utilizes the input and advice of the management team in making
purchase and sale determinations. 

Ralph Wanger is the president and chief strategist of the funds and has been
involved in managing all of the Acorn      

                                       26
<PAGE>
 
funds since each fund began (June 1970 for Acorn Fund, September 1992 for Acorn
International, and September 1996 for Acorn USA). Mr. Wanger has been president
and a member of the board of Acorn (and its predecessor, The Acorn Fund, Inc.)
since 1970. He is a principal of WAM and was a principal of the Fund's prior
advisor until July 1992. Mr. Wanger is primarily responsible for development of
the funds' investment strategies and is the lead portfolio manager of Acorn
Fund.

Charles P. McQuaid and Terence M. Hogan are co-portfolio managers of Acorn Fund.
Mr. McQuaid is a senior vice president and a trustee of the Trust. Mr. Hogan is
a vice president of the Trust. Mr. McQuaid and Mr. Hogan have been principals of
WAM since July 1992. Before that date, Mr. McQuaid was a principal and Mr. Hogan
was an analyst with the Trust's prior investment advisor. Mr. McQuaid and Mr.
Hogan have been working with Mr. Wanger for 19 and 11 years, respectively.

Leah J. Zell is the lead portfolio manager of Acorn International and is a vice
president of the Trust. She has been a principal of WAM since July 1992 and was
an analyst with the Trust's previous investment advisor. Ms. Zell has been
working with Mr. Wanger for 13 years.

Robert A. Mohn is a vice president of the Trust and has been the lead portfolio
manager of Acorn USA since it began operations in September 1996. Mr. Mohn has
been a key member of WAM's domestic analytical team since August 1992, and a
principal of WAM since July 1995.

Marcel P. Houtzager is a vice president of the Trust, and is a key member of the
international investment team. Mr. Houtzager joined WAM as an investment analyst
in April 1992, and became a principal in 1995. A specialist in foreign equities,
he concentrates his efforts on European stocks, for both the Acorn Fund and
Acorn International portfolios.     

The other executive officers are Merrillyn J. Kosier, vice president and
secretary, and Bruce H. Lauer, vice president and treasurer.

State Street Bank and Trust Company is each fund's transfer agent and custodian.

Distributor
    
Shares of the Acorn funds are offered for sale through WAM Brokerage Services,
L.L.C. ("WAM BD") without any sales commission or charges to the funds or their
shareholders. WAM BD is wholly-owned by WAM, the funds' investment advisor, and
the investment advisor's general partner, Wanger Asset Management, Ltd. WAM BD's
address is 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. All
distribution expenses relating to the funds are paid by WAM, including the
payment or reimbursement of any expenses incurred by WAM BD.     

                                       27
<PAGE>
 
 .The Funds in Detail, continued


Expenses

Like all mutual funds, the Acorn funds pay expenses related to their daily
operations. Expenses paid out of each fund's assets are reflected in its share
price or dividends. 

The Fund pays a management fee to WAM for managing its investments and business
affairs. See "Expenses and Performance." Each fund also pays the fees of its
custodian, transfer agent, auditors, and lawyers, and other expenses such as the
cost of compliance with federal and state laws, proxy solicitations, shareholder
reports, taxes, insurance premiums, and the fees of trustees who are not
otherwise affiliated with Acorn or WAM.

The Acorn Philosophy
    
Acorn Fund, Acorn International and Acorn USA seek long-term growth of capital.
Although income is considered in the selection of securities for the Acorn
funds, the funds are not designed for investors seeking primarily income rather
than capital appreciation.

Acorn prefers small companies. Since large institutions seek highly marketable
stocks, the stocks of large companies are studied in detail by security
analysts, with the result that all investors know much the same thing about
large companies. WAM prefers to work with stocks where values are more
attractive because the facts about the companies are not universally known.
Thus, the Acorn funds generally concentrate purchases on that segment of the
market where the competition is less intense--in companies with a total common
stock market capitalization of less than $1 billion. WAM wants to be able to
understand any company in which Acorn invests, and smaller companies are easier
to comprehend than large firms or conglomerates. When a company develops into a
multi-industry giant, it is difficult for even the top management of the company
to understand its own business and even harder for an outsider to follow such
widespread activities. Since WAM places a premium on understanding Acorn's
investments, WAM talks to top management directly whenever possible. This is
easier to do with smaller firms.

Looking for high quality companies. The funds look for quality businesses, with
each investment ideally resting on a solid tripod of growth potential, financial
strength, and fundamental value. Not all of the companies in which the funds
invest necessarily have all of these characteristics.

The sources of growth are a growing marketplace for the company's product, good
design, efficient manufacturing, sound marketing, and good profit margins.
Financial strength means low debt, adequate working capital, and conservative
accounting principles. Strong capitalization gives management the stability and
flexibility to reach strategic     

                                       28
<PAGE>
 
objectives. In economies with less well-developed capital markets than those of
the U.S., a strong balance sheet is an essential component of competitive
advantage. Fundamental value means low relative price. The existence of a good
company does not necessarily make its stock a good buy. The price of the stock
determines value as measured relative to dividends, earnings, cash flow, growth
rate, book value, and economic replacement value of assets. The emphasis on
fundamentals in relation to price sets the Acorn funds apart from pure "growth"
or "value" funds.

WAM also believes that finding and understanding high quality companies is
important because investing in smaller companies involves relatively higher
investment costs. One way to reduce these costs is to invest with a long-term
time horizon (at least 2-5 years) and to avoid frequent turnover of the stocks
held by the funds. Occasionally, however, securities purchased on a long-term
basis may be sold within 12 months after purchase in light of a change in the
circumstances of a particular company or industry, or in general market or
economic conditions.

Investment themes. To find long-term investments and reduce portfolio turnover,
the funds seek out areas of the economy that they believe will benefit from
favorable long-term economic and political trends. These areas of emphasis may
change from time to time, and are usually related to identified investment
themes or market niches. A small company can frequently carve out a specialized
niche for itself. The niche can be geographic, like that of a regional bank or a
community newspaper. It can be technological, based on patents and know-how.
Sometimes the niche is a marketing technique. In international investing, the
niche can be participation in a fast-growth economy. A well-run business in a
growing country has an easier path to a high growth rate.     

The funds invest primarily in equity securities, including common and preferred
stocks, warrants or other similar rights, and convertible securities. The funds
may purchase foreign securities in the form of American Depository Receipts
(ADRs), European Depository Receipts (EDRs), or other securities representing
underlying shares of foreign issuers. The funds may also invest in any other
type of security, including debt securities.
    
Under normal market conditions, Acorn International invests at least 75% of its
total assets, taken at market value, in foreign securities. Acorn USA may invest
up to 10% of its total assets in foreign securities. Acorn Fund's investments in
foreign securities are limited to no more than one-third of its total assets.
The foreign securities in which the funds invest may be traded in mature markets
(for example, Japan, Canada, and the United Kingdom) and in developing     

                                       29
<PAGE>
 
 .The Funds in Detail, continued

    
markets (Mexico and Indonesia, for example), examples of which are included in
the SAI under "Investment Techniques and Risks--Foreign Securities." There are
no limits on the funds' geographic asset distribution; at December 31, 1996,
Acorn International had investments in 41 countries and Acorn Fund had
investments in 34 countries. Acorn USA had no investment in foreign securities
at that date. The funds may invest without limit in corporate or government
obligations or hold cash or cash equivalents if WAM determines that a temporary
defensive position is advisable. If investments in foreign securities appear to
be relatively unattractive because of current or anticipated adverse political
or economic conditions, Acorn International may hold cash or invest any portion
of its assets in securities of the U.S. government and equity and debt
securities of U.S. companies, as a temporary defensive strategy. The funds use
various techniques to increase or decrease their exposure to the effects of
possible changes in security prices, currency exchange rates, or other factors
that affect the value of a fund's portfolio. These techniques include buying and
selling options, futures contracts, or options on futures contracts, or entering
into currency exchange contracts or swap agreements.

The investment objective of each Acorn fund is not fundamental and may be
changed by the board of trustees without shareholder approval. If there were
such a change, you should consider whether your fund would remain an appropriate
investment in light of your then current financial position and needs. The funds
are not intended, alone or together, to present a balanced investment program.
     
Securities, Investment Practices, and Risks

The following pages contain more detailed information about types of investments
the funds may make, and strategies WAM may employ in pursuit of each fund's
investment objective, including information about the associated risks and
restrictions. All policies stated throughout this prospectus, other than those
identified as fundamental, can be changed without shareholder approval. A
complete statement of each fund's investment restrictions is included in the
SAI. Policies and limitations are considered at the time of purchase; the sale
of an investment is not required because of a subsequent change in
circumstances.

WAM may not buy all of these instruments or use all of these techniques to the
fullest extent permitted, unless it believes that doing so will help a fund
achieve its goal.

Common stocks represent an equity (ownership) interest in a corporation. This
ownership interest often gives a fund the right to vote on measures affecting
the company's organization and

                                       30
<PAGE>
 
operations. Although common stocks have a history of long-term growth in value,
their prices tend to fluctuate in the short term.
    
The Acorn funds invest mostly in the securities of smaller companies, that is,
companies with a total market capitalization of less than $1 billion. During
some periods, the securities of small companies, as a class, have performed
better than the securities of large companies, and in some periods they have
performed worse. Stocks of small companies tend to be more volatile and less
liquid than stocks of large companies. Small companies, as compared to larger
companies, may have a shorter history of operations, may not have as great an
ability to raise additional capital, may have a less diversified product line
making them susceptible to market pressure, and may have a smaller public market
for their shares.

Restrictions: A fund may not acquire securities of any one issuer, which at the
time of investment (a) represent more than 10% of the voting securities of the
issuer or (b) have a value greater than 10% of the value of the outstanding
securities of the issuer.*     

Foreign Securities

International investing allows you to achieve greater diversification and to
take advantage of changes in foreign economies and market conditions. From time
to time, many foreign economies have grown faster than the U.S. economy, and the
returns on investments in these countries have exceeded those of similar U.S.
investments, although there can be no assurance that these conditions will
continue.
    
Investments in foreign securities provide opportunities different from those
available in the U.S., and risks which in some ways may be greater than in U.S.
investments, including: fluctuations in exchange rates of foreign currencies;
imposition of exchange control regulations or currency restrictions that would
prevent cash from being brought to the United States; less public information
with respect to issuers of securities; less governmental supervision of stock
exchanges, securities brokers, and issuers of securities; lack of uniform
accounting, auditing, and financial reporting standards; lack of uniform
settlement periods and trading practices; less liquidity, frequently greater
price volatility, and higher transaction costs in foreign markets than in the
United States; possible imposition of foreign taxes; possible investments in
securities of developing as well as developed countries; and sometimes less
advantageous legal, operational, and financial protections applicable to foreign
sub-custodial arrangements. Investing in countries outside the U.S. also
involves political risk. A foreign government might restrict investments by
foreigners, expropriate assets, seize or nationalize foreign     

- --------------------------------------------------------------------------------
*These restrictions are "fundamental," which means that they cannot be changed
 without shareholder approval.

                                       31
<PAGE>
 
 .The Funds in Detail, continued

    
bank deposits or other assets, establish exchange controls, or enact other
policies that could affect investment in these nations. Economies in individual
markets may differ favorably or unfavorably from the U.S. economy in such
respects as growth of gross domestic product, rates of inflation, currency
depreciation, capital reinvestment, resource self-sufficiency and balance of
payments positions. Many emerging market countries have experienced extremely
high rates of inflation for many years. That has had and may continue to have
very negative effects on the economies and securities markets of those
countries.     

The securities markets of emerging countries are substantially smaller, less
developed, less liquid, and more volatile than the securities markets of the
United States and other more developed countries. Disclosure and regulatory
standards in many respects are less stringent than in the U.S. There also may be
a lower level of monitoring and regulation in emerging markets of traders,
insiders, and investors. Enforcement of existing regulations has been extremely
limited.

The funds may invest in ADRs that are not sponsored by the issuer of the
underlying security. To the extent a fund does so, it would probably bear its
proportionate share of the expenses of the depository and might have greater
difficulty in receiving copies of the issuer's shareholder communications than
would be the case with a sponsored ADR.

The funds may invest in securities purchased on a when-issued and delayed
delivery basis. Although the payment terms of such a security are established at
the time a fund enters into the commitment, the security may be delivered and
paid for a month or more after the date of purchase, when its value may have
changed. A fund will make such commitments only with the intention of actually
acquiring the securities, but may sell the securities before settlement date if
WAM considers it advisable for investment reasons.
    
Restrictions: Under normal market conditions, Acorn International invests at
least 75% of its total assets in foreign securities. Acorn Fund's investments in
foreign securities are limited to not more than 33% of its total assets. Acorn
USA may invest up to 10% of its total assets in foreign securities, including
ADRs.     

Managing Investment Exposure 

The funds use various techniques to increase or decrease their exposure to the
effects of possible changes in security prices, currency exchange rates or other
factors that affect the value of the funds' portfolios. These techniques include
buying and selling options, futures contracts, or options on futures contracts,
or entering into currency exchange contracts or swap agreements.

These techniques are used by WAM to adjust the risk and return characteristics
of the funds' portfolios. If WAM judges market conditions incorrectly or employs

                                       32
<PAGE>
 
a strategy that does not correlate well with a fund's investments, or if the
counterparty to the transaction does not perform as promised, the transaction
could result in a loss. Use of these techniques may increase the volatility of a
fund and may involve a small investment of cash relative to the magnitude of the
risk assumed. These techniques are used by the funds for hedging, risk
management or portfolio management purposes and are not used for speculation.

Currency exchange transactions. A currency exchange transaction may be conducted
either on a spot (i.e., cash) basis at the spot rate for purchasing or selling
currency prevailing in the foreign exchange market or through a forward foreign
currency contract ("forward contract"). A forward contract is an agreement to
purchase or sell a specified currency at a specified future date (or within a
specified time period) and price set at the time of the contract. Forward
contracts are usually entered into with banks, foreign exchange dealers or
broker-dealers, are not exchange-traded, and are usually for less than one year,
but may be renewed.

Currency exchange transactions may involve currencies of the different countries
in which the funds may invest, and serve as hedges against possible variations
in the exchange rate between these currencies. The funds' currency transactions
are limited to transaction hedging and portfolio hedging involving either
specific transactions or actual or anticipated portfolio positions. Transaction
hedging is the purchase or sale of a forward contract with respect to a specific
receivable or payable of a fund accruing in connection with the purchase or sale
of portfolio securities. Portfolio hedging is the use of a forward contract with
respect to an actual or anticipated portfolio security position denominated or
quoted in a particular currency. The funds may engage in portfolio hedging with
respect to the currency of a particular country in amounts approximating actual
or anticipated positions in securities denominated in that currency. When a fund
owns or anticipates owning securities in countries whose currencies are linked,
WAM may aggregate those positions as to the currency hedged. Although forward
contracts may be used to protect a fund from adverse currency movements, the use
of such hedges may reduce or eliminate the potentially positive effect of
currency revaluations on that fund's total return.

Options and futures. Each fund may enter into stock index or currency futures
contracts (or options thereon) to hedge a portion of that fund's portfolio, to
provide an efficient means of regulating the fund's exposure to the equity
markets, or as a hedge against changes in prevailing levels of currency exchange
rates. Each fund may write covered call options and purchase put and call
options on foreign currencies, securities, and stock indices. Futures contracts
and options can be

                                       33
<PAGE>
 
 .The Funds in Detail, continued


highly volatile. A fund's attempt to use such investments for hedging purposes
may not be successful and could result in reduction of that fund's total return.

Restrictions: A fund will not use futures contracts for speculation, and will
limit its use of futures contracts so that no more than 5% of that fund's total
assets would be committed to initial margin deposits or premiums on such
contracts. The aggregate market value of each fund's currencies or portfolio
securities covering call or put options will not exceed 10% of that fund's net
assets.

Debt Securities. Bonds and other debt instruments are methods for an issuer to
borrow money from investors. The issuer pays the investor a fixed or variable
rate of interest, and must repay the amount borrowed at maturity. Debt
securities have varying degrees of quality and varying levels of sensitivity to
changes in interest rates.

"Investment grade" debt securities are those rated within the four highest
ratings categories of Standard & Poor's Corporation ("S&P") or Moody's Investors
Services, Inc. ("Moody's") or, if unrated, determined by WAM to be of comparable
quality. Securities rated BBB or Baa are considered to be medium-grade and to
have speculative characteristics. Investment in non-investment grade debt
securities is speculative and involves a high degree of risk.

Lower-rated debt securities (commonly called "junk bonds") are often considered
speculative and involve greater risk of default or price changes due to changes
in the issuer's creditworthiness. The market prices of these securities may
fluctuate more than higher-rated securities and may decline significantly in
periods of general economic difficulty.

Money market instruments are high-quality, short-term debt securities that
present minimal credit risk. These instruments may carry fixed or variable
interest rates.
    
Restrictions: There are no restrictions on the ratings of debt securities in
which a fund may invest. Acorn Fund does not intend to invest more than 5% of
its net assets in securities rated at or lower than the lowest investment grade.
Acorn International will not invest more than 20% of its total assets in debt
securities that are below investment grade quality. Acorn USA does not intend to
invest more than 20% of its total assets in debt securities, nor more than 5% of
its total assets in debt securities rated at or lower than the lowest investment
grade.

Acorn Fund and Acorn USA may invest without limit in corporate or government
obligations, or hold cash or cash equivalents if WAM determines that a temporary
defensive position is advisable. If investments in foreign securities appear to
be relatively unattractive because of current or anticipated adverse political
or     

                                       34
<PAGE>
 
    
economic conditions, Acorn International may hold cash or invest any portion of
its assets in securities of the U.S. government and equity and debt securities
of U.S. companies, as a temporary defensive strategy. To meet liquidity needs
(which, under normal market conditions, are not expected to exceed 25% of total
assets) or for temporary defensive purposes, each fund may hold cash in domestic
and foreign currencies and may invest in domestic and foreign money market
securities.      

Illiquid and Restricted Securities

Some investments may be determined by WAM to be illiquid, which means that they
may be difficult to sell promptly at an acceptable price. Other securities, such
as securities acquired in private placements, may be sold only pursuant to
certain legal restrictions. Difficulty in selling securities may result in
delays or a loss, or may be costly to the fund.

    
Restrictions: Acorn Fund may not purchase a security if, as a result, more than
10% of its assets would be invested in illiquid or restricted securities. Acorn
International and Acorn USA are similarly restricted with respect to 15% of
their assets.*      

Diversification

Diversifying the funds' investment portfolios can reduce the risks of investing.
This may include limiting the amount of money invested in any one company or, on
a broader scale, limiting the amount invested in any one industry or country.

    
Restrictions: Acorn Fund may not invest more than 5% of its total assets in the
securities of any one issuer. Acorn International and Acorn USA are similarly
limited with respect to 75% of their total assets, leaving a "basket" of 25% of
total assets in which investments may exceed the 5% limit. No fund may invest
more than 25% of its total assets in any one industry. These limitations do not
apply to U.S. government securities.*      

Other Investment Companies

Certain markets are closed in whole or in part to equity investments by
foreigners. The funds may be able to invest in such markets solely or primarily
through governmentally-authorized investment companies.

Investment in another investment company may involve the payment of a premium
above the value of the issuer's portfolio securities, and is subject to market
availability. In the case of a purchase of shares of such a company in a public
offering, the purchase price may include an underwriting spread. As a
shareholder in an investment company, a fund would bear its ratable share of
that investment company's expenses, including its advisory and administration
fees. At the same time, the fund would continue to pay its own management fees
and other expenses. The funds do not intend to invest in such circumstances
unless, in the judgment of WAM, the


- --------------------------------------------------------------------------------
*These restrictions are "fundamental," which means that they cannot be changed
 without shareholder approval.

                                       35
<PAGE>
 
 .The Funds in Detail, continued


potential benefits of such investment justify the payment of any applicable
premium or sales charge, and the additional layer of expense.

Restrictions: A fund generally may invest up to 10% of its assets in shares of
other investment companies and up to 5% of its assets in any one investment
company (in each case measured at the time of investment). No investment in
another investment company may represent more than 3% of the outstanding voting
stock of the acquired investment company at the time of investment.

    
Lending and Repurchase Agreements

The funds generally may not make loans, but have the power to invest in
repurchase agreements and reverse repurchase agreements (generally as a cash
management technique). A repurchase agreement involves a sale of securities to a
fund in which the seller agrees to repurchase the securities at a higher price,
which includes an amount representing interest on the purchase price, within a
specified time. In the event of a bankruptcy of the seller, a fund could
experience both losses and delays in liquidating its collateral.

Restrictions: A fund may not generally make loans, but may (a) invest in debt
securities within the limits described in the prospectus and SAI, (b) invest in
repurchase agreements or (c) lend up to 33% of its portfolio securities.*



                                     Fund
- --------------------------------------------------------------------------------
                                          Facts

Remember, you can use your touch-tone telephone to obtain your fund account
balance(s) 24 hours a day. Simply call 1-800-962-1585 and follow the automated
instructions.


- --------------------------------------------------------------------------------

*These restrictions are "fundamental," which means that they cannot be changed
 without shareholder approval.    

                                       36
<PAGE>
 
    
Highlights 
        .Doing Business with Acorn


From time to time you may find it necessary to make changes to your account
privileges or registration. The following easy-to-use shareholder forms are
available upon request by calling 1-800-9-ACORN-9 (1-800-922-6769):
 
- --------------------------------------------------------------------------------
To accomplish this:                     Please request this form:

For changes to account services         . Doing Business with Acorn 

For re-registering your current         . Changing Your Account Registration 
account 

For re-registering your Acorn           . Broker-Dealer Transfer Form
shares held by a broker to an 
account with Acorn

For changes to your IRA                 . Change of Beneficiary 
beneficiary designations 

For transferring money from             . IRA Transfer Form 
an IRA account with another 
institution to Acorn

For redeeming shares from your          . IRA Withdrawal Form
IRA account                                                                   


                                       37
<PAGE>
 
     
Highlights 
        .How to Buy Shares 
 

Mail                                                                     [LOGO]
- --------------------------------------------------------------------------------
        To open an account: 

      . Complete and sign the application. Make your check payable to "Acorn
        Fund," "Acorn International," or "Acorn USA."

        Mail to the address on the application, or for overnight delivery:
        Boston Financial Data Services
        Attn: Acorn Funds
        2 Heritage Drive, 6th Floor
        N. Quincy, MA 02171
        1-617-774-5000 ext. 6457 

      . Acorn does not accept third party checks.

- --------------------------------------------------------------------------------
        To add to an account: 

      . Make your check payable to "Acorn Fund," "Acorn International," or
        "Acorn USA." Put your fund account number on your check.

        Use the return envelope that comes with your statements, or mail to the
        address on your statement. 

      . Acorn does not accept third party checks.

Telephone: 1-800-962-1585                                                [LOGO]
- --------------------------------------------------------------------------------
        To open an account: 

      . You may not open a new account by telephone.

      . Exchange between the Acorn funds, or from a Reich & Tang Fund account
        with the same registration, including name, address, and taxpayer ID
        number.

- --------------------------------------------------------------------------------
        To add to an account: 

      . Exchange between accounts with the same registration, including name,
        address, and taxpayer ID number. 

      . Use the telephone purchase plan to transfer $100 to $50,000 from your
        bank account. Call first to verify that this service is in place on your
        account. (This service is not available for IRAs.)

You must make your telephone purchases or exchanges from the Acorn funds by
3:00 p.m. Central time.       

                                       38
<PAGE>
 
     
Wire                                                                     [logo]
- --------------------------------------------------------------------------------
        To open an account: 

      . Call 1-800-962-1585 to set up your account and to arrange a wire
        transaction. This is not available for IRA accounts.

- --------------------------------------------------------------------------------
        To add to an account: 

      . Wire to: 
        State Street Bank & Trust Co. 
        Attn: Mutual Funds
        Boston, MA 02110
        Routing #0110-0002-8
        Deposit DDA 9902-990-2
        Specify the name of the fund, the account name and the account number.


Automatic Investment Plan                                                [logo]
- --------------------------------------------------------------------------------
        To open an account: 

      . You may not open a new account through the Automatic Investment Plan.

- --------------------------------------------------------------------------------
        To add to an account: 

      . Sign up on the purchase application for monthly or quarterly transfers
        of $100 to $50,000 from your bank account, or call 1-800-9-ACORN-9 (1-
        800-922-6769) for a Doing Business with Acorn form. If you already have
        this service, you can easily change the frequency or amount of your
        automatic investments over the telephone by calling 1-800-962-1585.


- --------------------------------------------------------------------------------
TDD service for the deaf and hearing-impaired: 1-800-306-4567       

                                       39
<PAGE>
 
     
Highlights 
        .How to Sell Shares 


Telephone 1-800-962-1585                                                  [LOGO]
- --------------------------------------------------------------------------------
        All accounts types, except IRAs:        

      . To verify that the telephone redemption plan is in place, call 1-800-
        962-1585. You automatically have this feature on your new account unless
        you tell us that you do not want it.

      . Maximum: $50,000; minimum: $100

        All account types:      

      . To exchange between identically-registered accounts
        
You must make your telephone redemptions by Closing Time (usually 3:00 p.m.
Central time).

Mail                                                                      [LOGO]
- --------------------------------------------------------------------------------
        Individuals, Joint Owners, Sole Proprietorships, UGMA, UTMA     

      . The letter of instruction must be signed by all persons required to sign
        for transactions (usually, all owners of the account), exactly as their
        names appear on the account.

- --------------------------------------------------------------------------------
        IRAs    

      . The account owner should complete an IRA Withdrawal Request form. Call
        1-800-9-ACORN-9  (1-800-922-6769) to request one.

- --------------------------------------------------------------------------------
        Trust   

      . The trustee(s) must sign the letter indicating capacity as trustee(s).
        If the account registration does not include the name of the trustee(s),
        provide a copy of the trust document certified within the last 60 days.

- --------------------------------------------------------------------------------
        Business or Organization        

      . The person(s) authorized by the corporate resolution to act on the
        account must sign, in that person's official capacity, and the
        redemption request must be on corporate letterhead.

      . Include a corporate resolution certified within 60 days if the amount to
        be redeemed exceeds $50,000.

- --------------------------------------------------------------------------------
        Executor, Administrator, Conservator, Guardian  

      . Call 1-800-962-1585 for instructions.                         

                                       40
<PAGE>
 
     
Wire                                                                      [LOGO]
- --------------------------------------------------------------------------------
        All account types, except IRAs

      . You must sign up for payment of redemptions by wire before 
        using this feature. Call to verify that this service is in place--
        1-800-962-1585.

      . Minimum wire: $1,000; maximum: $50,000.

You must make your telephone redemptions by Closing time (usually 3:00 p.m.
Central time).

Automatic Exchange                                                        [LOGO]
- --------------------------------------------------------------------------------
        All account types 

      . Call 1-800-962-1585 to set up monthly or quarterly automatic exchanges
        of $100 to $50,000 between identically-registered accounts.


- --------------------------------------------------------------------------------
TDD service for the deaf and hearing-impaired: 1-800-306-4567 

Note: Some redemptions require signature guarantees. Please see page 13.       


                                       41
<PAGE>
 
     
Highlights 
        .How to Contact Us


Mail                                                                     [LOGO]
- --------------------------------------------------------------------------------

State Street Bank & Trust Co.   . for regular mail delivery, including 
Attn: Acorn funds                 purchases, written exchanges,
P. O. Box 8502                    redemptions, and IRA contributions
Boston, MA 02266-8502

Boston Financial Data Services  . for overnight deliveries of purchases,
Attn: Acorn funds                 written exchanges, redemptions, or 
2 Heritage Drive, 6th Floor       IRA contributions 
N. Quincy, MA 02171 

Wanger Asset Management, L.P.   . the funds' advisor
227 W. Monroe St., Suite 3000 
Chicago, IL 60606-5016 

WAM Brokerage Services, L.L.C.  . the funds' distributor
227 W. Monroe St., Suite 3000 
Chicago, IL 60606-5016 

Phone                                                                    [LOGO]
- --------------------------------------------------------------------------------

1-800-9-ACORN-9                 . for fund information, literature,  
(1-800-922-6769)                  prices, and performance information
                                  (from outside the U.S. 1-312-634-9240) 

1-800-962-1585                  . for account balances, telephone 
                                  purchases, exchanges and 
                                  redemptions, and for IRA informa-
                                  tion (from outside the U.S.
                                  1-617-774-5000 ext. 6457) 

1-800-221-3079                  . to exchange out of a money fund

1-800-306-4567                  . TDD service for the deaf and 
                                  hearing impaired

Customer service is available on business days from 8:00 a.m. to 4:30 p.m.
Central time. 

Telephone requests for purchases, redemptions or exchanges from the Acorn funds
must be made by Closing Time (usually 3:00 p.m. Central time).        

                                       42
<PAGE>
 
     
Internet                                                                 [LOGO]
- --------------------------------------------------------------------------------

Web site: www.wanger.com
E-mail: [email protected]

Wire                                                                     [LOGO]
- --------------------------------------------------------------------------------

State Street Bank & Trust Co.   . to wire money from your bank to 
Attn: Mutual Funds                add to an existing account 
Boston, MA 02110
Routing #0110-0002-8
Deposit DDA 9902-990-2 

Specify the name of the fund and 
the name and the number of 
your account.                                                         

                                       43
<PAGE>
 
[LOGO OF ACORN FAMILY OF FUNDS]

P.O. Box 8502
Boston, MA 02266-8502

Application

It takes only a few moments to fill out this simple step-by-step application. If
you have questions, call us at 1-800-9-ACORN-9, (1-800-922-6769), weekdays,
8:00am--4:30pm, Central time. Please be sure to print your information on this
application, then simply sign and return it to us in the postage-paid envelope
we've provided or to the address above. (Please do not use this form if you are
opening an IRA. Please call us at the telephone number above for an IRA
application.)

Your Account Registration

[_][_][_] [_][_] [_][_][_][_]
Social Security Number Use minor's social security number for gifts/transfers to
minors or

[_][_] [_][_][_][_][_][_][_]
Taxpayer ID Number

- --------------------------------------------------------------------------------
[_] Individual or Joint* Account


- --------------------------------------------------------------------------------
Owner's name: first, middle initial, last


- --------------------------------------------------------------------------------
Joint owner's name: first, middle initial, last


*Joint tenants with right of survivorship, unless you indicate otherwise.


- --------------------------------------------------------------------------------
[_] Gift/Transfer to a Minor (UGMA/UTMA)

                                                              as custodian for  
- --------------------------------------------------------------
Custodian's name (one name only): first, middle initial, last

                                                              under the    
- --------------------------------------------------------------
Minor's name: first, middle initial, last

                                          Uniform Gifts/Transfers to Minors Act.
- ------------------------------------------
State

- --------------------------------------------------------------------------------
Minor's date of birth


- --------------------------------------------------------------------------------
[_] Trust or Established Employee Benefit or Profit-Sharing Plan


- --------------------------------------------------------------------------------
Trustee(s') name(s)

                                                       as trustee(s) of
- -------------------------------------------------------
Trustee(s') name(s)


- --------------------------------------------------------------------------------
Name of Trust or Plan


- --------------------------------------------------------------------------------
Date of Trust or Plan


PLEASE INCLUDE A COPY OF FIRST PAGE AND LAST PAGES OF THE TRUST OR PLAN 
AGREEMENT.

- --------------------------------------------------------------------------------
[_] Corporation or Other Entity


- --------------------------------------------------------------------------------
Name of corporation or other entity


- --------------------------------------------------------------------------------
Type of entity (for example, corporation, partnership, non-profit)

PLEASE ATTACH A CERTIFIED COPY OF YOUR CORPORATE RESOLUTION SHOWING THE 
PERSON(S) AUTHORIZED TO ACT ON THIS ACCOUNT.


Institutional Accounts Only
- --------------------------------------------------------------------------------

Please complete the following:

[_] Defined Benefit                                         [_] Foundation

[_] Defined Contribution                                    [_] Endowment

    [_] 401(k)
    [_] 403(b)
    [_] 457 (b)

Investment Consulting firm name:
                                ------------------------------------------------


Address
- --------------------------------------------------------------------------------



- --------------------------------------------------------------------------------
Street or P.O. Box



- --------------------------------------------------------------------------------
City                                State                           Zip Code



- --------------------------------------------------------------------------------
Daytime phone, including area code



[_] U.S. Citizen                                [_] Non-citizen residing in U.S.


To invest, you must be a U.S. citizen (or a non-citizen residing in the U.S.) 
with a social security or tax identification number.


Choose Your Investments
- --------------------------------------------------------------------------------

There is an initial investment minimum of $1,000 per Fund.


[_] Acorn USA                       $
                                    --------------------------------------------
[_] Acorn International             $
                                    --------------------------------------------
[_] Acorn Fund                      $
                                    --------------------------------------------
    Total Investment                $
                                    --------------------------------------------

Make check(s) payable to Acorn USA, Acorn International, and/or Acorn Fund.  The
Acorn funds do not accept third party checks.

Dividend/Capital Gains Payment Options
- --------------------------------------------------------------------------------

Please choose how you want to receive your income dividends and capital gains.  
If no option is checked, all dividends and capital gains will be reinvested 
automatically. (Check one box.)

[_] Reinvest dividends and capital gains to help keep my account growing.

[_] Pay dividends and capital gains in cash.

[_] Pay dividends in cash; reinvest capital gains.


Duplicate Statements
- --------------------------------------------------------------------------------
[_] Please also send statments on my account to:


- --------------------------------------------------------------------------------
Name


- --------------------------------------------------------------------------------
Street or P.O. Box


- --------------------------------------------------------------------------------


- --------------------------------------------------------------------------------
City                              State                                 Zip Code



How Did You Hear About Us?
- --------------------------------------------------------------------------------

[_] press mention (specify)                    [_] advertising (specify)

    -----------------------                        --------------------

[_] I am a current  Acorn                      [_] Ralph Wanger's book:
    shareholder                                    A Zebra in Lion Country

[_] referred by friend/advisor                 [_] Other


                                                             (More on the back.)
<PAGE>
 
Automatic Investment Plan
- --------------------------------------------------------------------------------
To keep building your investments, you can easily add to your fund accounts
by joining the automatic investment plan:

[_]  Automatic Investment Plan: to add to your Acorn account automatically

[_]  Acorn USA                 $
                               ------------------------------   
[_]  monthly               [_] quarterly (check only one box)

[_]  Acorn International       $
                               ------------------------------                
[_]  monthly               [_] quarterly (check only one box)

[_]  Acorn Fund                $
                           [_] ------------------------------   
[_]  monthly                   quarterly (check only one box)

The minimum automatic investment is $100; the maximum is $50,000. Your automatic
investment will be drawn from your bank account on or about the 15th of the
month; quarterly investments are made in January, April, July and October.
Attach a voided check from the bank account you will be using.

Bank Transfer Options
- --------------------------------------------------------------------------------
To make transactions fast and easy, choose the Telephone Purchase Plan,
Telephone Redemption by Wire Plan, or both. It takes about 10 days to set up
these plans. Telephone requests for purchases or redemptions must be made by
Closing Time (usually 3:00 p.m. Central time).

[_]  Telephone Purchase Plan: to add to your Acorn Fund account, Acorn
     International account or Acorn USA account by transferring money from your
     bank checking account ($100 minimum, $50,000 maximum per transfer.)

[_]  Telephone Redemptions by Wire: to redeem shares and transfer the money to
     your bank checking account ($1,000 minimum, $50,000 maximum per
     transaction.) 

Attach a voided check from the bank account you will be using.

Telephone Plans
- --------------------------------------------------------------------------------
You automatically have the ability to exchange and redeem shares by telephone
unless you check the boxes below. Proceeds of telephone redemption requests are
paid by check, mailed to the address of record and may not be more than $50,000.
Exchanges must be between identically-registered accounts and requested by
Closing Time (usually 3:00 p.m. Central time). See the prospectus for details.

I do not want
     ---

[_]  telephone exchanges                              [_]  telephone redemptions



Agreement
- --------------------------------------------------------------------------------
By signing this form, I certify that:

I am of legal age, have received and read the prospectus, and agree to its
terms. I understand that each of the account services, including the telephone
exchange plan, may be terminated or modified by Acorn in the future.

If I fail to give the correct social security or taxpayer identification number
or to sign this form, Acorn Fund, Acorn International, or Acorn USA may reject,
restrict, or redeem my investment.

I authorize Acorn Fund, Acorn International, Acorn USA, and their affiliates and
agents to act on any instructions reasonably believed to be genuine for any
service authorized on this form (including telephone transactions). I agree that
they will not be liable for any resulting loss or expense. I certify that I have
read the explanation and agree to the terms and provisions for the services I
have elected as set forth in the current prospectus of Acorn Fund, Acorn
International, and Acorn USA, as amended from time to time.

(If you have elected the Automatic Investment Plan or any Bank Transfer Option)
I authorize Acorn Fund, Acorn International, Acorn USA, and their affiliates and
agents to initiate (1) credit entries (deposits) (if I have elected the
Telephone Redemption Bank Transfer Option), (2) debit entries (withdrawals) (if
I have elected to participate in the Automatic Investment Plan or Telephone
Purchase Bank Transfer Option), and (3) debit or credit entries and adjustments
for any entries made in error to my bank account, for which I have attached a
voided check. This authorization will remain effective until I notify Acorn in
writing or by telephone at 1-800-962-1585 of its termination and until Acorn has
a reasonable time to act on that termination.

Under penalty, I certify that (i) the Social Security or Tax Identification
Number given is correct and (ii) I am NOT currently subject to IRS backup
withholding for failure to report dividend or interest income to the IRS.
(Please cross out "NOT" if you are currently subject to withholding.) The IRS
does not require your consent to any provision of this document, other than the
certifications in this paragraph required to avoid backup withholding.

Signature(s)
- --------------------------------------------------------------------------------


X
- --------------------------------------------------------------------------------
Signature (Sign exactly as name appears in Account Registration)    Date


X
- --------------------------------------------------------------------------------
Signature (Sign exactly as name appears in Account Registration)    Date

Joint accounts require both signatures.
Trust accounts require the signatures of all trustees.
<PAGE>
 
Acorn                                                       FIRST CLASS
- --------------------                                       U.S. POSTAGE
     Family of Funds                                           PAID
                                                            CHICAGO, IL
                                                          PERMIT NO. 1200
WAM Brokerage Services, L.L.C.
P.O. Box 8502
Boston, MA 02266-8502


<PAGE>
 
                                                          ACORN INVESTMENT TRUST
                                                                    STATEMENT OF
                                                                      ADDITIONAL
                                                                     INFORMATION
                                                                  April 30, 1997


                                                          227 West Monroe Street
                                                                      Suite 3000
                                                         Chicago, Illinois 60606
                                                                 1-800-9-ACORN-9
                                                                  1-800-922-6769

ACORN FUND
ACORN INTERNATIONAL
ACORN USA

No-Load Funds

                               TABLE OF CONTENTS
                               -----------------
                                                            Page
                                                            ----
<TABLE>
<CAPTION>
 
 
<S>                                                      <C>
     Information About the Funds............................. 2
     Investment Objectives and Policies...................... 2
     Investment Techniques and Risks......................... 2
     Investment Restrictions.................................16
     Performance Information.................................23
     Investment Adviser......................................24
     Distributor.............................................25
     The Trust...............................................26
     Trustees and Officers...................................26
     Purchasing and Redeeming Shares.........................29
     Additional Tax Information..............................31
     Taxation of Foreign Shareholders........................32
     Portfolio Transactions..................................32
     Custodian...............................................33
     Independent Auditors....................................34
     Appendix - Description of Bond Ratings..................35
</TABLE>

     This Statement of Additional Information ("SAI") is not a prospectus but
provides information that should be read in conjunction with the prospectus of
Acorn Fund, Acorn International and Acorn USA dated April 30, 1997 and any
supplement thereto, which may be obtained from Acorn at no charge by writing or
telephoning Acorn at its address or telephone number shown above.

                                       1
<PAGE>
 
                          Information About the Funds

     Acorn Fund, Acorn International and Acorn USA are series of Acorn
Investment Trust ("Acorn" or the "Trust").  All three funds are currently open
to new investors; however, Acorn reserves the right to close one or more of the
funds to new investors if additional cash flow is deemed detrimental to
management of the funds.

     The 1996 Annual Report of the Acorn funds, a copy of which accompanies this
SAI, contains financial statements, notes thereto, supplementary information
entitled "Financial Highlights," and a report of independent auditors, all of
which (but no other part of the Annual Report) are incorporated herein by
reference.  Additional copies of the Annual Report may be obtained from Acorn at
no charge by writing or telephoning Acorn at its address or telephone number
shown on the cover page of this SAI.

     The discussion below supplements the description in the prospectus of the
funds' investment objectives, policies, and restrictions.


                      Investment Objectives and Policies

     Acorn Fund, Acorn International and Acorn USA invest with the objective of
long-term growth of capital.  Although income is considered in the selection of
securities, the funds are not designed for investors seeking primarily income
rather than capital appreciation.

     The funds use the techniques and invest in the types of securities
described below and in the prospectus.


                        Investment Techniques and Risks

Foreign Securities

     The funds invest in foreign securities, which may entail a greater degree
of risk (including risks relating to exchange rate fluctuations, tax provisions,
or expropriation of assets) than does investment in securities of domestic
issuers.  Under normal market conditions, Acorn International invests at least
75% of its total assets in foreign securities; Acorn Fund's and Acorn USA's
investments in foreign securities are limited to not more than 33% and 10% of
each fund's total assets, respectively.  The funds may invest in securities of
foreign issuers directly or in the form of American Depositary Receipts (ADRs),
European Depositary Receipts (EDRs), or other securities representing underlying
shares of foreign issuers.  Positions in these securities are not necessarily
denominated in the same currency as the common stocks into which they may be
converted.  ADRs are receipts typically issued by an American bank or trust
company evidencing ownership of the underlying securities.  EDRs are European
receipts evidencing a similar arrangement.  Generally ADRs, in registered form,
are designed for use in the U.S. securities markets and EDRs, in bearer form,
are designed for use in European securities markets.  The funds may invest in
both "sponsored" and "unsponsored" ADRs.  In a sponsored ADR, the issuer
typically pays some or all of the expenses of the depository and agrees to
provide its regular shareholder communications to ADR holders.  An unsponsored
ADR is 

                                       2
<PAGE>
 
created independently of the issuer of the underlying security.  The ADR
holders generally pay the expenses of the depository and do not have an
undertaking from the issuer of the underlying security to furnish shareholder
communications.  Therefore, in the case of an unsponsored ADR, a fund is likely
to bear its proportionate share of the expenses of the depository and it may
have greater difficulty in receiving shareholder communications than it would
have with a sponsored ADR.  None of the funds expects to invest 5% or more of
its total assets in unsponsored ADRs.

     The funds' investment performance is affected by the strength or weakness
of the U.S. dollar against the currencies of the foreign markets in which its
securities trade or in which they are denominated.  For example, if the dollar
falls in value relative to the Japanese yen, the dollar value of a yen-
denominated stock held in the portfolio will rise even though the price of the
stock remains unchanged.  Conversely, if the dollar rises in value relative to
the yen, the dollar value of the yen-denominated stock will fall.  (See
discussion of transaction hedging and portfolio hedging under "Currency Exchange
Transactions.")

     Investors should understand and consider carefully the risks involved in
foreign investing.  Investing in foreign securities, positions in which are
generally denominated in foreign currencies, and utilization of forward foreign
currency exchange contracts involve risks and opportunities not typically
associated with investing in U.S. securities.  These considerations include:
fluctuations in exchange rates of foreign currencies; possible imposition of
exchange control regulation or currency restrictions that would prevent cash
from being brought back to the United States; less public information with
respect to issuers of securities; less governmental supervision of stock
exchanges, securities brokers, and issuers of securities; lack of uniform
accounting, auditing, and financial reporting standards; lack of uniform
settlement periods and trading practices; less liquidity and frequently greater
price volatility in foreign markets than in the United States; possible
imposition of foreign taxes; possible investment in securities of companies in
developing as well as developed countries; and sometimes less advantageous
legal, operational, and financial protections applicable to foreign subcustodial
arrangements.  In addition, the costs of investing in foreign securities are
higher than the costs of investing in U.S. securities.

     Although the funds try to invest in companies and governments of countries
having stable political environments, there is the possibility of expropriation
or confiscatory taxation, seizure or nationalization of foreign bank deposits or
other assets, establishment of exchange controls, the adoption of foreign
government restrictions, or other adverse political, social, or diplomatic
developments that could affect investment in these nations.

     The countries in which the funds invest include those listed below.  A fund
may not invest in all the countries listed, and it may invest in other countries
as well, when such investments are consistent with that fund's investment
objective and policies.
                        
                                       3
<PAGE>
 
 Mature Markets   Developing Markets         Emerging Markets
 --------------   ------------------         ----------------
<TABLE>
<CAPTION>
  <S>                <C>                <C>             <C> 
   Australia           Argentina         Bangladesh      Morocco
   Austria             Chile             Botswana        Pakistan
   Belgium             Greece            Brazil          Peru
   Canada              Hong Kong         China           Philippines
   Denmark             Indonesia         Colombia        Poland
   Finland             Israel            Cyprus          Sri Lanka
   France              Korea             Czech Republic  Swaziland
   Germany             Malaysia          Ecuador         Turkey
   Ireland             Mexico            Egypt           Uruguay
   Italy               Portugal          Ghana           Venezuela
   Japan               Singapore         Hungary         Zambia 
   Luxembourg          Taiwan            India           Zimbabwe
   Netherlands         Thailand          Jordan
   New Zealand                           Kenya
   Norway
   South Africa
   Spain
   Sweden
   Switzerland
   United Kingdom
   United States
</TABLE>

     It may not be feasible for the funds currently to invest in all of these
countries due to restricted access to their securities markets or inability to
implement satisfactory custodial arrangements.

Currency Exchange Transactions

     The funds may enter into currency exchange transactions.  A currency
exchange transaction may be conducted either on a spot (i.e., cash) basis at the
spot rate for purchasing or selling currency prevailing in the foreign exchange
market or through a forward currency exchange contract ("forward contract").  A
forward contract is an agreement to purchase or sell a specified currency at a
specified future date (or within a specified time period) and price set at the
time of the contract.  Forward contracts are usually entered into with banks,
foreign exchange dealers or broker-dealers, are not exchange-traded, and are
usually for less than one year, but may be renewed.

     Forward currency transactions may involve currencies of the different
countries in which the funds may invest, and serve as hedges against possible
variations in the exchange rate between these currencies.  The funds' currency
transactions are limited to transaction hedging and portfolio hedging involving
either specific transactions or portfolio positions, except to the extent
described below under "Synthetic Foreign Money Market Positions."  Transaction
hedging is the purchase or sale of a forward contract with respect to specific
payables or receivables of a fund accruing in connection with the purchase or
sale of portfolio securities.  Portfolio hedging is the use of a forward
contract with respect to a portfolio security position denominated or quoted in
a particular currency.  The funds may engage in portfolio hedging with respect
to the currency of a particular country in amounts approximating actual or
anticipated positions in securities 

                                       4
<PAGE>
 
denominated in that currency. When a fund owns or anticipates owning securities
in countries whose currencies are linked, WAM may aggregate such positions as to
the currency hedged.

     If a fund enters into a forward contract hedging an anticipated purchase of
portfolio securities, assets of that fund having a value at least as great as
the fund's commitment under such forward contract will be segregated on the
books of the fund and held by the custodian while the contract is outstanding.

     At the maturity of a forward contract to deliver a particular currency, a
fund may either sell the portfolio security related to such contract and make
delivery of the currency, or it may retain the security and either acquire the
currency on the spot market or terminate its contractual obligation to deliver
the currency by purchasing an offsetting contract with the same currency trader
obligating it to purchase on the same maturity date the same amount of the
currency.

     It is impossible to forecast with absolute precision the market value of
portfolio securities at the expiration of a forward contract.  Accordingly, it
may be necessary for a fund to purchase additional currency on the spot market
(and bear the expense of such purchase) if the market value of the security is
less than the amount of currency that the fund is obligated to deliver and if a
decision is made to sell the security and make delivery of the currency.
Conversely, it may be necessary to sell on the spot market some of the currency
received upon the sale of the portfolio security if its market value exceeds the
amount of currency that fund is obligated to deliver.

     If a fund retains the portfolio security and engages in an offsetting
transaction, that fund will incur a gain or a loss to the extent that there has
been movement in forward contract prices.  If the fund engages in an offsetting
transaction, it may subsequently enter into a new forward contract to sell the
currency.  Should forward prices decline during the period between a fund's
entering into a forward contract for the sale of a currency and the date it
enters into an offsetting contract for the purchase of the currency, the fund
will realize a gain to the extent the price of the currency it has agreed to
sell exceeds the price of the currency it has agreed to purchase.  Should
forward prices increase, a fund will suffer a loss to the extent the price of
the currency it has agreed to purchase exceeds the price of the currency it has
agreed to sell.  A default on the contract would deprive the fund of unrealized
profits or force the fund to cover its commitments for purchase or sale of
currency, if any, at the current market price.

     Hedging against a decline in the value of a currency does not eliminate
fluctuations in the prices of portfolio securities or prevent losses if the
prices of such securities decline.  Such transactions also preclude the
opportunity for gain if the value of the hedged currency should rise.  Moreover,
it may not be possible for a fund to hedge against a devaluation that is so
generally anticipated that the fund is not able to contract to sell the currency
at a price above the devaluation level it anticipates.  The cost to a fund of
engaging in currency exchange transactions varies with such factors as the
currency involved, the length of the contract period, and prevailing market
conditions.  Since currency exchange transactions are usually conducted on a
principal basis, no fees or commissions are involved.

                                       5
<PAGE>
 
     Synthetic Foreign Money Market Positions.  The funds may invest in money
market instruments denominated in foreign currencies.  In addition to, or in
lieu of, such direct investment, the funds may construct a synthetic foreign
money market position by (a) purchasing a money market instrument denominated in
one currency (generally U.S. dollars) and (b) concurrently entering into a
forward contract to deliver a corresponding amount of that currency in exchange
for a different currency on a future date and at a specified rate of exchange.
For example, a synthetic money market position in Japanese yen could be
constructed by purchasing a U.S. dollar money market instrument, and entering
concurrently into a forward contract to deliver a corresponding amount of U.S.
dollars in exchange for Japanese yen on a specified date and at a specified rate
of exchange.  Because of the availability of a variety of highly liquid short-
term U.S. dollar money market instruments, a synthetic money market position
utilizing such U.S. dollar instruments may offer greater liquidity than direct
investment in foreign money market instruments.  The results of a direct
investment in a foreign currency and a concurrent construction of a synthetic
position in such foreign currency, in terms of both income yield and gain or
loss from changes in currency exchange rates, in general should be similar, but
would not be identical because the components of the alternative investments
would not be identical.  Except to the extent a synthetic foreign money market
position consists of a money market instrument denominated in a foreign
currency, the synthetic foreign money market position shall not be deemed a
"foreign security" for purposes of the policies that, under normal conditions,
(a) Acorn Fund will not invest more than 33% of its total assets in foreign
securities; (b) Acorn USA will not invest more than 10% of its total assets in
foreign securities; and (c) Acorn International will invest at least 75% of its
total assets in foreign securities.

Options and Futures

     The funds may purchase and write both call options and put options on
securities and on indexes, and enter into interest rate and index futures
contracts, and may purchase or sell options on such futures contracts ("futures
options") in order to provide additional revenue, or to hedge against changes in
security prices or interest rates.  The funds may also use other types of
options, futures contracts and futures options currently traded or subsequently
developed and traded, provided the board of trustees determines that their use
is consistent with the funds' investment objective.

     Options.  An option on a security (or index) is a contract that gives the
purchaser (holder) of the option, in return for a premium, the right to buy from
(call) or sell to (put) the seller (writer) of the option the security
underlying the option (or the cash value of the index) at a specified exercise
price at any time during the term of the option (normally not exceeding nine
months).  The writer of an option on an individual security or on a foreign
currency has the obligation upon exercise of the option to deliver the
underlying security or foreign currency upon payment of the exercise price or to
pay the exercise price upon delivery of the underlying security or foreign
currency.  Upon exercise, the writer of an option on an index is obligated to
pay the difference between the cash value of the index and the exercise price
multiplied by the specified multiplier for the index option.  (An index is
designed to reflect specified facets of a particular financial or securities
market, a specific group of financial instruments or securities, or certain
economic indicators.)
                                    
                                       6
<PAGE>
 
     The funds will write call options and put options only if they are
"covered."  For example, in the case of a call option on a security, the option
is "covered" if a fund owns the security underlying the call or has an absolute
and immediate right to acquire that security without additional consideration
(or, if additional consideration is required, assets having a value at least
equal to that amount are segregated on the books of a fund) upon conversion or
exchange of other securities held in its portfolio.

     If an option written by a fund expires, that fund realizes a capital gain
equal to the premium received at the time the option was written.  If an option
purchased by a fund expires, that fund realizes a capital loss equal to the
premium paid.

     Prior to the earlier of exercise or expiration, an option may be closed out
by an offsetting purchase or sale of an option of the same series (type,
exchange, underlying security or index, exercise price and expiration).  There
can be no assurance, however, that a closing purchase or sale transaction can be
effected when a fund desires.

     A fund will realize a capital gain from a closing purchase transaction if
the cost of the closing option is less than the premium received from writing
the option, or, if it is more, the fund will realize a capital loss.  If the
premium received from a closing sale transaction is more than the premium paid
to purchase the option, the fund will realize a capital gain or, if it is less,
the fund will realize a capital loss.  The principal factors affecting the
market value of a put or a call option include supply and demand, interest
rates, the current market price of the underlying security or index in relation
to the exercise price of the option, the volatility of the underlying security
or index, and the time remaining until the expiration date.

     A put or call option purchased by a fund is an asset of that fund, valued
initially at the premium paid for the option.  The premium received for an
option written by a fund is recorded as a deferred credit.  The value of an
option purchased or written is marked-to-market daily and is valued at the
closing price on the exchange on which it is traded or, if not traded on an
exchange or no closing price is available, at the mean between the last bid and
asked prices.

     OTC Derivatives.  The funds may buy and sell over-the-counter ("OTC")
derivatives.  Unlike exchange-traded derivatives, which are standardized with
respect to the underlying instrument, expiration date, contract size, and strike
price, the terms of OTC derivatives (derivatives not traded on exchanges)
generally are established through negotiation with the other party to the
contract.  While this type of arrangement allows a fund greater flexibility to
tailor an instrument to its needs, OTC derivatives generally involve greater
credit risk than exchange-traded derivatives, which are guaranteed by the
clearing organization of the exchanges where they are traded.  Each fund will
limit its investments so that no more than 5% of its total assets will be placed
at risk in the use of OTC derivatives.  See "Illiquid Securities" below for more
information on the risks associated with investing in OTC derivatives.

     Risks Associated with Options.  There are several risks associated with
transactions in options.  For example, there are significant differences between
the securities markets, the currency markets, and the options markets that could
result in an imperfect correlation between these markets, causing a given
transaction not to achieve its objectives.  A decision as to
                       
                                       7
<PAGE>
 
whether, when, and how to use options involves the exercise of skill and
judgment, and even a well-conceived transaction may be unsuccessful to some
degree because of market behavior or unexpected events.

     There can be no assurance that a liquid market will exist when a fund seeks
to close out an option position.  If a fund were unable to close out an option
that it had purchased on a security, it would have to exercise the option in
order to realize any profit or the option would expire and become worthless.  If
a fund were unable to close out a covered call option that it had written on a
security, it would not be able to sell the underlying security until the option
expired.  As the writer of a covered call option on a security, a fund foregoes,
during the option's life, the opportunity to profit from increases in the market
value of the security covering the call option above the sum of the premium and
the exercise price of the call.  As the writer of a covered call option on a
foreign currency, a fund foregoes, during the option's life, the opportunity to
profit from currency appreciation.

     If trading were suspended in an option purchased or written by one of the
funds, that fund would not able to close out the option.  If restrictions on
exercise were imposed, the fund might be unable to exercise an option it has
purchased.

     Futures Contracts and Options on Futures Contracts.  The funds may use
interest rate futures contracts and index futures contracts.  An interest rate
or index futures contract provides for the future sale by one party and purchase
by another party of a specified quantity of a financial instrument or the cash
value of an index /1/ at a specified price and time.  A public market exists in
futures contracts covering a number of indexes (including, but not limited to:
the Standard & Poor's 500 Index; the Value Line Composite Index; the Russell
2000 Index; and the New York Stock Exchange Composite Index) as well as
financial instruments (including, but not limited to: U.S. Treasury bonds; U.S.
Treasury notes; Eurodollar certificates of deposit; and foreign currencies).
Other index and financial instrument futures contracts are available and it is
expected that additional futures contracts will be developed and traded.

     The funds may purchase and write call and put futures options.  Futures
options possess many of the same characteristics as options on securities and
indexes (discussed above).  A futures option gives the holder the right, in
return for the premium paid, to assume a long position (call) or short position
(put) in a futures contract at a specified exercise price at any time during the
period of the option.  Upon exercise of a call option, the holder acquires a
long position in the futures contract and the writer is assigned the opposite
short position.  In the case of a put option, the opposite is true.


/1/  A futures contract on an index is an agreement pursuant to which two
parties agree to take or make delivery of an amount of cash equal to the
difference between the value of the index at the close of the last trading day
of the contract and the price at which the index contract was originally
written.  Although the value of a securities index is a function of the value of
certain specified securities, no physical delivery of those securities is made.
                   
                                       8
<PAGE>
 
     To the extent required by regulatory authorities having jurisdiction over
the funds, the funds will limit their use of futures contracts and futures
options to hedging transactions. For example, the funds might use futures
contracts to hedge against fluctuations in the general level of stock prices,
anticipated changes in interest rates, or currency fluctuations that might
adversely affect either the value of a fund's securities or the price of the
securities that a fund intends to purchase. The funds' hedging may include sales
of futures contracts as an offset against the effect of expected declines in
stock prices or currency exchange rates or increases in interest rates and
purchases of futures contracts as an offset against the effect of expected
increases in stock prices or currency exchange rates or declines in interest
rates. Although other techniques could be used to reduce the funds' exposure to
stock price, interest rate, and currency fluctuations, the funds may be able to
hedge their exposure more effectively and perhaps at a lower cost by using
futures contracts and futures options.

     The success of any hedging technique depends on WAM correctly predicting
changes in the level and direction of stock prices, interest rates, currency
exchange rates, and other factors. Should those predictions be incorrect, a
fund's return might have been better had hedging not been attempted; however, in
the absence of the ability to hedge, WAM might have taken portfolio actions in
anticipation of the same market movements with similar investment results but,
presumably, at greater transaction costs.

     When a purchase or sale of a futures contract is made by a fund, that fund
is required to deposit with its custodian (or broker, if legally permitted) a
specified amount of cash or U.S. government securities or other securities
acceptable to the broker ("initial margin"). The margin required for a futures
contract is generally set by the exchange on which the contract is traded;
however, the margin requirement may be modified during the term of the contract,
and the fund's broker may require margin deposits in excess of the minimum
required by the exchange. The initial margin is in the nature of a performance
bond or good faith deposit on the futures contract, which is returned to the
fund upon termination of the contract, assuming all contractual obligations have
been satisfied. The funds expect to earn interest income on their initial margin
deposits. A futures contract held by a fund is valued daily at the official
settlement price of the exchange on which it is traded. Each day the fund pays
or receives cash, called "variation margin," equal to the daily change in value
of the futures contract. This process is known as "marking-to-market." Variation
margin paid or received by a fund does not represent a borrowing or loan by the
fund but is instead settlement between that fund and the broker of the amount
one would owe the other if the futures contract had expired at the close of the
previous day. In computing daily net asset value, the funds will mark-to-market
their open futures positions.

     The funds are also required to deposit and maintain margin with respect to
put and call options on futures contracts they write. Such margin deposits will
vary depending on the nature of the underlying futures contract (and the related
initial margin requirements), the current market value of the option, and other
futures positions held by the funds.

     Although some futures contracts call for making or taking delivery of the
underlying securities, usually these obligations are closed out prior to
delivery by offsetting purchases or


                                       9

<PAGE>
 
sales of matching futures contracts (same exchange, underlying security or
index, and delivery month). If an offsetting purchase price is less than the
original sale price, the funds realize a capital gain, or if it is more, the
funds realize a capital loss. Conversely, if an offsetting sale price is more
than the original purchase price, the fund engaging in the transaction realizes
a capital gain, or if it is less, the fund realizes a capital loss. The
transaction costs must also be included in these calculations.

     Risks Associated with Futures.  There are several risks associated with the
use of futures contracts and futures options as hedging techniques. A purchase
or sale of a futures contract may result in losses in excess of the amount
invested in the futures contract. There can be no guarantee that there will be a
correlation between price movements in the hedging vehicle and in the portfolio
securities being hedged. In addition, there are significant differences between
the securities and futures markets that could result in an imperfect correlation
between the markets, causing a given hedge not to achieve its objectives. The
degree of imperfection of correlation depends on circumstances such as:
variations in speculative market demand for futures, futures options, and the
related securities, including technical influences in futures and futures
options trading and differences between the funds' investments being hedged and
the securities underlying the standard contracts available for trading. For
example, in the case of index futures contracts, the composition of the index,
including the issuers and the weighting of each issue, may differ from the
composition of a fund's portfolio, and, in the case of interest rate futures
contracts, the interest rate levels, maturities, and creditworthiness of the
issues underlying the futures contract may differ from the financial instruments
held in a fund's portfolio. A decision as to whether, when, and how to hedge
involves the exercise of skill and judgment, and even a well-conceived hedge may
be unsuccessful to some degree because of market behavior or unexpected stock
price or interest rate trends.

     Futures exchanges may limit the amount of fluctuation permitted in certain
futures contract prices during a single trading day. The daily limit establishes
the maximum amount that the price of a futures contract may vary either up or
down from the previous day's settlement price at the end of the current trading
session. Once the daily limit has been reached in a futures contract subject to
the limit, no more trades may be made on that day at a price beyond that limit.
The daily limit governs only price movements during a particular trading day and
therefore does not limit potential losses because the limit may work to prevent
the liquidation of unfavorable positions. For example, futures prices have
occasionally moved to the daily limit for several consecutive trading days with
little or no trading, thereby preventing prompt liquidation of positions and
subjecting some holders of futures contracts to substantial losses. Stock index
futures contracts are not normally subject to such daily price change
limitations.

     There can be no assurance that a liquid market will exist at a time when a
fund seeks to close out a futures or futures option position. The fund would be
exposed to possible loss on the position during the interval of inability to
close, and would continue to be required to meet margin requirements until the
position is closed. In addition, many of the contracts discussed above are
relatively new instruments without a significant trading history. As a result,
there can be no assurance that an active secondary market will develop or
continue to exist.


                                       10

<PAGE>
 
     Limitations on Options and Futures.  A fund will not enter into a futures
contract or purchase an option thereon if, immediately thereafter, the initial
margin deposits for futures contracts held by that fund plus premiums paid by it
for open futures option positions, less the amount by which any such positions
are "in-the-money," /2/ would exceed 5% of the fund's total assets.

     When purchasing a futures contract or writing a put option on a futures
contract, a fund must maintain with its custodian (or broker, if legally
permitted) cash or cash equivalents (including any margin) equal to the market
value of such contract. When writing a call option on a futures contract, a fund
similarly will maintain with its custodian cash or cash equivalents (including
any margin) equal to the amount by which such option is in-the-money until the
option expires or is closed out by the fund.

     A fund may not maintain open short positions in futures contracts, call
options written on futures contracts, or call options written on indexes if, in
the aggregate, the market value of all such open positions exceeds the current
value of the securities in its portfolio, plus or minus unrealized gains and
losses on the open positions, adjusted for the historical relative volatility of
the relationship between the portfolio and the positions. For this purpose, to
the extent a fund has written call options on specific securities in its
portfolio, the value of those securities will be deducted from the current
market value of the securities portfolio.

     In order to comply with Commodity Futures Trading Commission Regulation 4.5
and thereby avoid being deemed a "commodity pool operator," the "underlying
commodity value" of each long position in a commodity contract in which a fund
invests will not at any time exceed the sum of:

     (1)  The value of short-term U.S. debt obligations or other U.S. dollar
          denominated high-quality short-term money market instruments and cash
          set aside in an identifiable manner, plus any funds deposited as
          margin on the contract;

     (2)  Unrealized appreciation on the contract held by the broker; and

     (3)  Cash proceeds from existing investments due in not more than 30 days.

     "Underlying commodity value" means the size of the contract multiplied by
the daily settlement price of the contract.

     No fund will purchase puts, calls, straddles, spreads, or any combination
thereof if by reason of such purchase more than 10% of that fund's total assets
would be invested in such securities.



/2/  A call option is "in-the-money" if the value of the futures contract that
     is the subject of the option exceeds the exercise price. A put option is
     "in-the-money" if the exercise price exceeds the value of the futures
     contract that is the subject of the option.


                                       11

<PAGE>
 
     Swap Agreements.  A swap agreement is generally individually negotiated and
structured to include exposure to a variety of different types of investments or
market factors. Depending on its structure, a swap agreement may increase or
decrease a fund's exposure to changes in the value of an index of securities in
which the fund might invest, the value of a particular security or group of
securities, or foreign currency values. Swap agreements can take many different
forms and are known by a variety of names. A fund may enter into any form of
swap agreement if WAM determines it is consistent with that fund's investment
objective and policies, but each fund will limit its use of swap agreements so
that no more than 5% of its total assets will be placed at risk.

     A swap agreement tends to shift a fund's investment exposure from one type
of investment to another. For example, if a fund agrees to exchange payments in
dollars at a fixed rate for payments in a foreign currency the amount of which
is determined by movements of a foreign securities index, the swap agreement
would tend to increase that fund's exposure to foreign stock market movements
and foreign currencies. Depending on how it is used, a swap agreement may
increase or decrease the overall volatility of a fund's investments and its net
asset value.

     The performance of a swap agreement is determined by the change in the
specific currency, market index, security, or other factors that determine the
amounts of payments due to and from a fund. If a swap agreement calls for
payments by a fund, that fund must be prepared to make such payments when due.
If the counterparty's creditworthiness declines, the value of a swap agreement
would be likely to decline, potentially resulting in a loss. The fund expects to
be able to eliminate its exposure under any swap agreement either by assignment
or by other disposition, or by entering into an offsetting swap agreement with
the same party or a similarly creditworthy party.

     A fund will segregate its assets to cover its current obligations under a
swap agreement. If a fund enters into a swap agreement on a net basis, it will
segregate assets with a daily value at least equal to the excess, if any, of
that fund's accumulated obligations under the swap agreement over the
accumulated amount the fund is entitled to receive under the agreement. If a
fund enters into a swap agreement on other than a net basis, it will segregate
assets with a value equal to the full amount of that fund's accumulated
obligations under the agreement.


Illiquid Securities

     The funds may not invest in illiquid securities, including restricted
securities and OTC derivatives, if as a result they would comprise more than 10%
of the value of the net assets of Acorn Fund, or more than 15% of the value of
the net assets of each of Acorn International and Acorn USA.

     Restricted securities may be sold only in privately negotiated transactions
or in a public offering with respect to which a registration statement is in
effect under the Securities Act of 1933 (the "1933 Act"). Where registration is
required, a fund may be obligated to pay all or part of the registration
expenses and a considerable period may elapse between the time of the


                                       12

<PAGE>
 
decision to sell and the time the fund may be permitted to sell a security under
an effective registration statement. If, during such a period, adverse market
conditions were to develop, the fund might obtain a less favorable price than
prevailed when it decided to sell. Restricted securities will be priced at fair
value as determined in good faith by the board of trustees. If, through the
appreciation of illiquid securities or the depreciation of liquid securities,
Acorn Fund should be in a position where more than 10% of the value of its net
assets are invested in illiquid assets, including restricted securities and OTC
derivatives (or more than 15% of the value of the net assets of each of Acorn
International and Acorn USA), that fund will take appropriate steps to protect
liquidity.

     Notwithstanding the above, a fund may purchase securities that have been
privately placed but that are eligible for purchase and sale under Rule 144A
under the 1933 Act. That rule permits certain qualified institutional buyers,
such as the funds, to trade in privately placed securities that have not been
registered for sale under the 1933 Act. WAM, under the supervision of the board
of trustees, will consider whether securities purchased under Rule 144A are
illiquid and thus subject to a fund's restriction of investing no more than 10%
(for Acorn Fund) or 15% (for Acorn International and Acorn USA) of its assets in
illiquid securities. A determination of whether a Rule 144A security is liquid
or not is a question of fact. In making this determination WAM will consider the
trading markets for the specific security taking into account the unregistered
nature of a Rule 144A security. In addition, WAM could consider the (1)
frequency of trades and quotes, (2) number of dealers and potential purchasers,
(3) dealer undertakings to make a market, and (4) nature of the security and of
market place trades (e.g., the time needed to dispose of the security, the
method of soliciting offers and the mechanics of transfer). The liquidity of
Rule 144A securities would be monitored and if, as a result of changed
conditions, it is determined that a Rule 144A security is no longer liquid, the
funds' holdings of illiquid securities would be reviewed to determine what, if
any, steps are required to assure that a fund does not invest more than 10% (for
Acorn Fund) or 15% (for Acorn International and Acorn USA) of its assets in
illiquid securities. Investing in Rule 144A securities could have the effect of
increasing the amount of a fund's assets invested in illiquid securities if
qualified institutional buyers are unwilling to purchase such securities.


Debt Securities

     The funds may invest in debt securities, including lower-rated securities
(i.e., securities rated BB or lower by Standard & Poor's Corporation ("S&P") or
Ba or lower by Moody's Investor Services, Inc. ("Moody's"), commonly called
"junk bonds"), and securities that are not rated. There are no restrictions as
to the ratings of debt securities acquired by the funds or the portion of a
fund's assets that may be invested in debt securities in a particular ratings
category, except that Acorn International may not invest more than 20% of its
assets in securities rated below investment grade or considered by the Adviser
to be of comparable credit quality. Neither Acorn Fund nor Acorn International
expects to invest more than 5% of its net assets in such securities during the
current fiscal year. Acorn USA does not intend to invest more than 20% of its
total assets in debt securities nor more than 5% of its total assets in
securities rated at or lower than the lowest investment grade.


                                       13

<PAGE>
 
     Securities rated BBB or Baa are considered to be medium grade and to have
speculative characteristics. Lower-rated debt securities are predominantly
speculative with respect to the issuer's capacity to pay interest and repay
principal. Investment in medium- or lower-quality debt securities involves
greater investment risk, including the possibility of issuer default or
bankruptcy. An economic downturn could severely disrupt the market for such
securities and adversely affect the value of such securities. In addition, 
lower-quality bonds are less sensitive to interest rate changes than higher-
quality instruments and generally are more sensitive to adverse economic changes
or individual corporate developments. During a period of adverse economic
changes, including a period of rising interest rates, the junk bond market may
be severely disrupted, and issuers of such bonds may experience difficulty in
servicing their principal and interest payment obligations.

     Medium- and lower-quality debt securities may be less marketable than
higher-quality debt securities because the market for them is less broad. The
market for unrated debt securities is even narrower. During periods of thin
trading in these markets, the spread between bid and asked prices is likely to
increase significantly, and a fund may have greater difficulty selling its
portfolio securities. See "Net Asset Value." The market value of these
securities and their liquidity may be affected by adverse publicity and investor
perceptions.

     A more complete description of the characteristics of bonds in each ratings
category is included in the appendix to this SAI.


Repurchase Agreements

     Repurchase agreements are transactions in which a fund purchases a security
from a bank or recognized securities dealer and simultaneously commits to resell
that security to the bank or dealer at an agreed-upon price, date, and market
rate of interest unrelated to the coupon rate or maturity of the purchased
security. Although repurchase agreements carry certain risks not associated with
direct investments in securities, a fund will enter into repurchase agreements
only with banks and dealers believed by WAM to present minimum credit risks in
accordance with guidelines approved by the board of trustees. WAM will review
and monitor the creditworthiness of such institutions, and will consider the
capitalization of the institution, WAM's prior dealings with the institution,
any rating of the institution's senior long-term debt by independent rating
agencies, and other relevant factors.

     A fund will invest only in repurchase agreements collateralized at all
times in an amount at least equal to the repurchase price plus accrued interest.
To the extent that the proceeds from any sale of such collateral upon a default
in the obligation to repurchase were less than the repurchase price, the fund
would suffer a loss. If the financial institution which is party to the
repurchase agreement petitions for bankruptcy or otherwise becomes subject to
bankruptcy or other liquidation proceedings there may be restrictions on a
fund's ability to sell the collateral and the fund could suffer a loss. However,
with respect to financial institutions whose bankruptcy or liquidation
proceedings are subject to the U.S. Bankruptcy Code, each fund intends to comply
with provisions under such Code that would allow it immediately to resell such
collateral.


                                       14

<PAGE>
 
     At present, Acorn USA is the only fund that invests in repurchase
agreements.  Acorn Fund and Acorn International have no present intention of
investing in repurchase agreements.

When-Issued and Delayed Delivery Securities; Reverse Repurchase Agreements
                       
     The funds may purchase securities on a when-issued or delayed delivery
basis.  Although the payment and interest terms of these securities are
established at the time the fund enters into the commitment, the securities may
be delivered and paid for a month or more after the date of purchase, when their
value may have changed.  A fund makes such commitments only with the intention
of actually acquiring the securities, but may sell the securities before the
settlement date if WAM deems it advisable for investment reasons.  A fund may
utilize spot and forward foreign currency exchange transactions to reduce the
risk inherent in fluctuations in the exchange rate between one currency and
another when securities are purchased or sold on a when-issued or delayed
delivery basis.

     A fund may enter into reverse repurchase agreements with banks and
securities dealers.  A reverse repurchase agreement is a repurchase agreement in
which the fund is the seller of, rather than the investor in, securities and
agrees to repurchase them at an agreed-upon time and price.  Use of a reverse
repurchase agreement may be preferable to a regular sale and later repurchase of
securities because it avoids certain market risks and transaction costs.

     At the time a fund enters into a binding obligation to purchase securities
on a when-issued basis or enters into a reverse repurchase agreement, assets of
the fund having a value at least as great as the purchase price of the
securities to be purchased will be segregated on the books of the fund and held
by the custodian throughout the period of the obligation.  The use of these
investment strategies, as well as any borrowing by a fund, may increase net
asset value fluctuation.

     The funds have no present intention of investing in reverse repurchase
agreements.

Temporary Strategies

     The funds have the flexibility to respond promptly to changes in market and
economic conditions.  In the interest of preserving shareholders' capital, WAM
may employ a temporary defensive investment strategy if it determines such a
strategy to be warranted.  Pursuant to such a defensive strategy, a fund
temporarily may hold cash (U.S. dollars, foreign currencies, multinational
currency units) and/or invest up to 100% of its assets in high quality debt
securities or money market instruments of U.S. issuers (or, in the case of Acorn
Fund and Acorn International, those of foreign issuers), and most or all of the
fund's investments may be made in the United States and denominated in U.S.
dollars.  It is impossible to predict whether, when, or for how long a fund
might employ defensive strategies.

     In addition, pending investment of proceeds from new sales of fund shares
or to meet ordinary daily cash needs, a fund temporarily may hold cash (U.S.
dollars, foreign currencies, or multinational currency units) and may invest any
portion of its assets in money market instruments.

                                      15
<PAGE>
 
Portfolio Turnover

     Although the funds do not purchase securities with a view to rapid
turnover, there are no limitations on the length of time that portfolio
securities must be held. Portfolio turnover can occur for a number of reasons
such as general conditions in the securities markets, more favorable investment
opportunities in other securities, or other factors relating to the desirability
of holding or changing a portfolio investment. The funds' portfolio turnover
rates have been low (in 1996, 33% for Acorn Fund, 34% for Acorn International,
and 20% (annualized) for Acorn USA). A high rate of portfolio turnover, if it
should occur, would result in increased transaction expenses which must be borne
by each fund. High portfolio turnover may also result in the realization of
capital gains or losses and, to the extent net short-term capital gains are
realized, any distributions resulting from such gains will be considered
ordinary income for federal income tax purposes.


                            Investment Restrictions

Acorn Fund

     In pursuing its investment objective Acorn Fund will not:

     1.  Invest more than 5% of its assets (valued at time of investment) in
     securities of any one issuer, except in government obligations;

     2.  Acquire securities of any one issuer which at the time of investment
     (a) represent more than 10% of the voting securities of issuer or (b) have
     a value greater than 10% of the outstanding securities of the issuer;

     3.  Invest more than 25% of its assets (valued at time of investment) in
     securities of companies in any one industry;

     4.  Invest more than 5% of its assets (valued at time of investment) in
     securities of issuers with less than three years' operation (including
     predecessors);

     5.  Purchase or retain securities of a company if all of the trustees and
     officers of the Trust and of its investment adviser who individually own
     beneficially more than 1/2% of the securities of the company collectively
     own beneficially more than 5% of such securities;

     6.  Borrow money except (a) from banks for temporary or emergency purposes
     at fixed rates of interest in amounts not exceeding 10% of the value of the
     fund's assets at the time of borrowing, and (b) in connection with
     transactions in options and in securities index futures [the fund will not
     purchase additional securities when its borrowings, less amounts receivable
     on sales of portfolio securities, exceed 5% of total assets];

                                      16
<PAGE>
 
     7.   Pledge, mortgage or hypothecate its assets, except for temporary or
     emergency purposes and then to an extent not greater than 15% of its assets
     at cost, and except in connection with transactions in options and in
     securities index futures;

     8.   Underwrite the distribution of securities of other issuers; however
     the fund may acquire "restricted" securities which, in the event of a
     resale, might be required to be registered under the Securities Act of 1933
     on the ground that the fund could be regarded as an underwriter as defined
     by that act with respect to such resale; but the fund will limit its total
     investment in restricted securities and in other securities for which there
     is no ready market to not more than 10% of its total assets at the time of
     acquisition;

     9.   Purchase and sell real estate or interests in real estate, although it
     may invest in marketable securities of enterprises which invest in real
     estate or interests in real estate;

     10.  Purchase and sell commodities or commodity contracts, except that it
     may enter into (a) futures and options on futures and (b) forward
     contracts;

     11.  Make margin purchases of securities, except for use of such short-term
     credits as are needed for clearance of transactions and except in
     connection with transactions in options, futures and options on futures;

     12.  Sell securities short or maintain a short position, except short sales
     against-the-box;

     13.  Participate in a joint or on a joint or several basis in any trading
     account in securities;

     14.  Invest in companies for the purpose of management or the exercise of
     control;

     15.  Issue any senior security except to the extent permitted under the
     Investment Company Act of 1940.

     Restrictions 1 through 15 above (except the portions in brackets) are
"fundamental," which means that they cannot be changed without the approval of
the lesser of (i) 67% of Acorn Fund's shares present at a meeting if more than
50% of the shares outstanding are present or (ii) more than 50% of Acorn Fund's
outstanding shares.  It is also a fundamental policy of Acorn Fund to make loans
to the extent that investment in debt securities may be considered to constitute
the making of loans (subject to the 10% limitation stated in restriction 8
above).

     In addition, Acorn Fund is subject to a number of restrictions that may be
changed by the board of trustees without shareholder approval.  Under those non-
fundamental restrictions, Acorn Fund will not:

     a.   Invest in oil, gas or other mineral leases or exploration or 
     development programs, although it may invest in marketable securities of 
     enterprises engaged in oil, gas or mineral exploration;

                                       17
<PAGE>
 
     b.  Invest more than 5% of its net assets (valued at time of investment) in
     warrants, valued at the lower of cost or market, including not more than 2%
     of its net assets in warrants not listed on the New York or American stock
     exchanges; provided that warrants acquired in units or attached to
     securities shall be deemed to be without value for purposes of this
     restriction;

     c.  Acquire securities of other registered investment companies except in
     compliance with the Investment Company Act of 1940 and applicable state
     law;
                                                
     d.  Purchase a put or call option if the aggregate premiums paid for all
     put and call options exceed 20% of its net assets (less the amount by which
     any such positions are in-the-money), excluding put and call options
     purchased as closing transactions; nor
                           
     e.  Invest more than 33% of its total assets (valued at time of investment)
     in securities of foreign issuers.



Acorn International 

     In pursuing its investment objective Acorn International will not:

     1.  With respect to 75% of the value of the fund's total assets, invest
     more than 5% of its total assets (valued at time of investment) in
     securities of a single issuer, except securities issued or guaranteed by
     the government of the U.S., or any of its agencies or instrumentalities;

     2.  Acquire securities of any one issuer that at the time of investment (a)
     represent more than 10% of the voting securities of the issuer or (b) have
     a value greater than 10% of the value of the outstanding securities of the
     issuer;

     3.  Invest more than 25% of its assets (valued at time of investment) in 
     securities of companies in any one industry;

     4.  Make loans, but this restriction shall not prevent the fund from (a) 
     buying a part of an issue of bonds, debentures, or other obligations that
     are publicly distributed, or from investing up to an aggregate of 15% of
     its total assets (taken at market value at the time of each purchase) in
     parts of issues of bonds, debentures or other obligations of a type
     privately placed with financial institutions, (b) investing in repurchase
     agreements, or (c) lending portfolio securities, provided that it may not
     lend securities if, as a result, the aggregate value of all securities
     loaned would exceed 33% of its total assets (taken at market value at the
     time of such loan);

     5.  Borrow money except (a) from banks for temporary or emergency purposes
     in amounts not exceeding 10% of the value of the fund's total assets at the
     time of borrowing, and (b) in connection with transactions in options,
     futures and options on

                                      18
<PAGE>
 
     futures. [The fund will not purchase additional securities when its
     borrowings, less amounts receivable on sales of portfolio securities,
     exceed 5% of total assets.];

     6.  Underwrite the distribution of securities of other issuers; however the
     fund may acquire "restricted" securities which, in the event of a resale,
     might be required to be registered under the Securities Act of 1993 on the
     ground that the fund could be regarded as an underwriter as defined by that
     act with respect to such resale; but the fund will limit its total
     investment in restricted securities and in other securities for which there
     is no ready market, including repurchase agreements maturing in more than
     seven days, to not more than 15% of its total assets at the time of
     acquisition;

     7.  Purchase and sell real estate or interests in real estate, although it
     may invest in marketable securities of enterprises that invest in real
     estate or interests in real estate;

     8.  Purchase and sell commodities or commodity contracts, except that it
     may enter into (a) futures and options on futures and (b) forward
     contracts;

     9.  Make margin purchases of securities, except for use of such short-term
     credits as are needed for clearance of transactions and except in
     connection with transactions in options, futures and options on futures;

     10. Sell securities short or maintain a short position, except short sales 
     against-the-box.

     11.  Issue any senior security except to the extent permitted under the 
     Investment Company Act of 1940.

     Restrictions 1 through 11 above (except the portions in brackets) are 
"fundamental," which means that they cannot be changed without the approval of 
the lesser of (i) 67% of Acorn International's shares present at a meeting if 
more than 50% of the shares outstanding are present of (ii) more than 50% of the
shares outstanding are present or (ii) more than 50% of Acorn International's 
outstanding shares.

     In addition, Acorn International is subject to a number of restrictions 
that may be changed by the board of trustees without shareholder approval. Under
those non-fundamental restrictions, Acorn International will not:

     a.  Invest in companies for the purpose of management or the exercise of 
     control;

     b.  Invest in oil, gas or other mineral leases or exploration or
     development programs, although it may invest in marketable securities of
     enterprises engaged in oil, gas or mineral exploration;

     c.  Invest more than 10% of its net assets (valued at time of investment)
     in warrants, valued at the lower of cost or market; provided that warrants
     acquired in units or attached to securities shall be deemed to be without
     value for purposes of this restriction;

                                      19
<PAGE>
 
     d. Invest more than 5% of its total assets (valued at time of investment)
in securities of issuers with less than three years' operation (including
predecessors);

     e. Acquire securities of other registered investment companies except in
compliance with the Investment Company Act of 1940 and applicable state law;

     f. Purchase or retain securities of a company if all of the trustees,
directors and officers of the Trust and of its investment adviser who
individually own beneficially more than 1/2% of the securities of the company
collectively own beneficially more than 5% of such securities;

     g. Pledge, mortgage or hypothecate its assets, except as may be necessary
in connection with permitted borrowings or in connection with short sales,
options, futures and options on futures;

     h. Purchase a put or call option if the aggregate premiums paid for all put
and call options exceed 20% of its net assets (less the amount by which any such
positions are in-the-money), excluding put and call options purchased as closed
transactions.

     Notwithstanding the foregoing investment restrictions, Acorn International
may purchase securities pursuant to the exercise of subscription rights,
provided that such purchase will not result in the fund's ceasing to be a
diversified investment company.  Japanese and European corporations frequently
issue additional capital stock by means of subscription rights offerings to
existing shareholders at a price substantially below the market price of the
shares.  The failure to exercise such rights would result in Acorn
International's interest in the issuing company being diluted.  The market for
such rights is not well developed in all cases and, accordingly, Acorn
International may not always realize full value on the sale of rights.  The
exception applies in cases where the limits set forth in the investment
restrictions would otherwise be exceeded by exercising rights or would have
already been exceeded as a result of fluctuations in the market value of Acorn
International's portfolio securities with the result that the fund would be
forced either to sell securities at a time when it might not otherwise have done
so, or to forego exercising its rights.
    
Acorn USA

     In pursuing its investment objective Acorn USA will not:

     1. With respect to 75% of the value of the Fund's total assets, invest more
than 5% of its total assets (valued at time of investment) in securities of a
single issuer, except securities issued or guaranteed by the government of the
U.S., or any of its agencies or instrumentalities;

     2. Acquire securities of any one issuer which at the time of investment (a)
represent more than 10% of the voting securities of the issuer or (b) have a
value greater than 10% of the value of the outstanding securities of the issuer;

                                       20
<PAGE>
 
     3. Invest more than 25% of its assets (valued at time of investment) in
securities of companies in any one industry, except that restriction does not
apply to investments in U.S. government securities;

     4. Make loans, but this restriction shall not prevent the Fund from (a)
buying a part of an issue of bonds, debentures, or other obligations that are
publicly distributed, or from investing up to an aggregate of 15% of its total
assets (taken at market value at the time of each purchase) in parts of issues
of bonds, debentures or other obligations of a type privately placed with
financial institutions, (b) investing in repurchase agreements, or (c) lending
portfolio securities, provided that it may not lend securities if, as a result,
the aggregate value of all securities loaned would exceed 33% of its total
assets (taken at market value at the time of such loan);

     5. Borrow money except (a) from banks for temporary or emergency purposes
in amounts not exceeding 33% of the value of the Fund's total assets at the time
of borrowing, and (b) in connection with transactions in options, futures and
options on futures;

     6. Underwrite the distribution of securities of other issuers; however, the
Fund may acquire "restricted" securities which, in the event of a resale, might
be required to be registered under the Securities Act of 1933 on the ground that
the Fund could be regarded as an underwriter as defined by that act with respect
to such resale;

     7. Purchase and sell real estate or interests in real estate, although it
may invest in marketable securities of enterprises which invest in real estate
or interests in real estate;

     8. Purchase and sell commodities or commodity contracts, except that it may
enter into (a) futures and options on futures and (b) foreign currency
contracts;

     9. Make margin purchases of securities, except for use of such short-term
credits as are needed for clearance of transactions and except in connection
with transactions in options, futures and options on futures;

    10. Issue any senior security except to the extent permitted under the
Investment Company Act of 1940.

     Restrictions 1 through 10 above are "fundamental," which means that they
cannot be changed without the approval of the lesser of (i) 67% of Acorn USA's
shares present at a meeting if more than 50% of the shares outstanding are
present or (ii) more than 50% of Acorn USA's outstanding shares.

     In addition, Acorn USA is subject to a number of restrictions that may be
changed by the board of trustees without shareholder approval. Under those non-
fundamental restrictions, Acorn USA will not:

     a. Invest in companies for the purpose of management or the exercise of
control;

                                      21
<PAGE>
 
     b.   Invest in oil, gas or other mineral leases or exploration or
development programs, although it may invest in marketable securities of
enterprises engaged in oil, gas or mineral exploration;

     c.   Invest more than 2% of its net assets (valued at the time of
investment) in warrants not listed on the New York or American Stock exchanges,
nor more than 5% of its net assets (valued at the time of investment) in all
warrants, in each case valued at the lower of cost or market; provided that
warrants acquired in units or attached to securities shall be deemed to be
without value for purposes of this restriction;

     d.   Invest more than 5% of its total assets (valued at time of investment)
in securities of issuers (other than issuers of federal agency obligations or
securities issued or guaranteed by any foreign country or asset-backed
securities) that, together with any predecessors or unconditional guarantors,
have been in continuous operation for less than three years ("unseasoned
issuers") or (b) more than 15% of its total assets (valued at the time of
investment) in restricted securities and securities of unseasoned issuers;

     e.   Acquire securities of other registered investment companies except in
compliance with the Investment Company Act of 1940 and applicable state law;/3/

     f.   Invest more than 15% of its net assets (valued at time of investment)
in illiquid securities, including repurchase agreements maturing in more than
seven days;

     g.   Purchase or retain securities of a company if all of the trustees,
directors and officers of the Trust and of its investment adviser who
individually own beneficially more than 1/2% of the securities of the company
collectively own beneficially more than 5% of such securities;

     h.   Pledge, mortgage or hypothecate its assets, except as may be necessary
in connection with permitted borrowings or in connection with short sales,
options, futures and options on futures;

     i.   Purchase a put or call option if the aggregate premiums paid for all
put and call options exceed 20% of its net assets (less the amount by which any
such positions are in-the-money), excluding put and call options purchased as
closing transactions;

     j.   Make short sales of securities unless the Fund owns at least an equal
amount of such securities, or owns securities that are convertible or
exchangeable, without payment of further consideration, into at least an equal
amount of such securities;

     k.   Invest more than 10% of its total assets (valued at the time of
investment) in securities of non-U.S. issuers, including securities represented
by American Depository Receipts.

                                      22
<PAGE>
 
Notwithstanding the foregoing investment restrictions, Acorn USA may purchase
securities pursuant to the exercise of subscription rights, provided that such
purchase will not result in the Fund's ceasing to be a diversified investment
company.

                            Performance Information

     From time to time the funds may quote total return figures. "Total Return"
for a period is the percentage change in value during the period of an
investment in shares of a fund, including the value of shares acquired through
reinvestment of all dividends and capital gains distributions.  "Average Annual
Total Return" is the average annual compounded rate of change in value
represented by the Total Return for the period.

     Average Annual Total Return is computed as follows:

          ERV = P(1+T)/n/

     Where: P = the amount of an assumed initial investment in shares of a fund
            T = average annual total return
            n = number of years from initial investment to the end of the period
            ERV = ending redeemable value of shares held at the end of the 
                  period


     For example, as of December 31, 1996 the Total Return and Average Total
Return on a $1,000 investment in the funds for the following periods were:
    
<TABLE>
<CAPTION>
     ACORN FUND
     ----------
                                                          Average Annual
                                         Total Return      Total Return
                                         ------------     --------------
     <S>                                 <C>              <C>

     1 year............................     22.6%               22.6%
     5 years...........................    125.2%               17.6
     10 years..........................    345.5%               16.1
     Life of Fund (inception 6/10/70)..  5,995.7%               16.7

     ACORN INTERNATIONAL
     -------------------
                                                          Average Annual
                                         Total Return      Total Return
                                         ------------     --------------

     1 year............................     20.7%               20.7%
     3 years...........................     26.4%                8.1
     Life of Fund (inception 9/23/92)..    101.3%               17.8

     ACORN USA
     ---------
                                                          Average Annual
                                         Total Return     Total Return
                                         ------------     --------------
     Life of Fund (inception 9/4/96)...     16.5%              16.5%
</TABLE>      

                                       23
<PAGE>
 
     The funds impose no sales charges and pay no distribution expenses.  Income
taxes are not taken into account.  Performance figures quoted by the funds are
not necessarily indicative of future results.  Each fund's performance is a
function of conditions in the securities markets, portfolio management, and
operating expenses.  Although information about past performance is useful in
reviewing a fund's performance and in providing some basis for comparison with
other investment alternatives, it should not be used for comparison with other
investments using different reinvestment assumptions or time periods.

     In advertising and sales literature, each fund's performance may be
compared with those of market indexes and other mutual funds.  In addition to
the performance information described above, a fund might use comparative
performance as computed in a ranking or rating determined by Lipper Analytical
Services, Inc., an independent service that monitors the performance of over
1,000 mutual funds, Morningstar, Inc., or another service.

     The funds may note their mention or recognition in newsletters, newspapers,
magazines, or other media.  The funds may similarly note mention or recognition
of WAM, or appearances of principals of WAM, in the media.

                               Investment Adviser

     The funds' investment adviser, Wanger Asset Management, L.P. ("WAM"),
furnishes continuing investment supervision to the funds and is responsible for
overall management of the funds' business affairs.   It furnishes office space,
equipment, and personnel to the funds; it assumes substantially all expenses for
bookkeeping, and assumes the expenses of printing and distributing the funds'
prospectus and reports to prospective investors.

     For its services to Acorn Fund WAM receives a quarterly fee (paid in three
monthly installments) at the annual rate of .75% of the net asset value of the
fund up to $100 million, .50% of the net asset value in excess of $100 million
and up to $1.5 billion, and .40% of the net asset value in excess of $1.5
billion, as determined as of the beginning of each calendar quarter.  The
investment advisory fees of the fund for 1996, 1995, and 1994, were $12,437,000,
$10,429,000 and $9,750,000, respectively.

     For its services to Acorn International, WAM receives a fee paid monthly at
the annual rate of 1.25% of the net asset value of the fund up to $100 million,
1% of the net asset value in excess of $100 million and up to $500 million, and
 .80% of the net asset value in excess of $500 million, as determined as of the
beginning of each calendar quarter, reduced by any amount necessary to cause the
fund's expenses to be within the limitation described below.  The investment
advisory fees of Acorn International for 1996, 1995 and 1994 were $13,255,000,
$11,667,000 and $11,561,000, respectively.

     For its services to Acorn USA, WAM receives a fee (calculated daily and
paid monthly) at the annual rate of 1.00% of the net asset value of the fund up
to $200 million and .95% of the net asset value in excess of $200 million, as
determined as of the beginning of each calendar quarter.  From its inception on
September 4, 1996 to December 31, 1996, Acorn USA paid investment advisory fees
of $101,000.

                                       24
<PAGE>
 
     The funds pay the cost of custodial, stock transfer, dividend disbursing,
audit, and legal services, and membership in trade organizations.  They also pay
other expenses such as the cost of maintaining the registration of their shares
under federal law, complying with state securities laws, proxy solicitations,
printing and distributing notices and copies of the prospectus and shareholder
reports furnished to existing shareholders, taxes, insurance premiums, and the
fees of trustees not affiliated with WAM.

     The investment advisory agreement provides that the total annual expenses
of each fund, exclusive of taxes, interest, and extraordinary litigation
expenses, but including fees paid to WAM, shall not exceed the limits prescribed
by any state in which that fund's shares are being offered for sale.  Acorn
believes that currently the most restrictive limits are 2.5% of the first $30
million of the average net asset value, 2% of the next $70 million, and 1.5% of
the average net asset value in excess of $100 million.  Brokers' commissions and
other charges relating to the purchase and sale of securities are not regarded
as expenses for this purpose.  Moreover, for purposes of calculating the
expenses subject to this limitation, the excess custodian costs attributable to
investments in foreign securities compared to the custodian costs which would
have been incurred had the investments been in domestic securities are excluded.
For the purpose of determining whether the fund is entitled to any reduction in
advisory fee or expense reimbursement, the fund's expenses are calculated
monthly and any reduction in fee or reimbursement is made monthly.  Each fund's
operating expenses have been well below those limitations.

     WAM advanced all of Acorn International's organizational expenses, which
are being amortized and reimbursed to WAM through September, 1997.  WAM also
advanced all of Acorn USA's organizational expenses, which are being amortized
and reimbursed to WAM through September 2001.

     WAM is a limited partnership managed by its general partner, Wanger Asset
Management, Ltd., which is controlled by Ralph Wanger.  WAM commenced operations
in 1992.  Ralph Wanger, Charles P. McQuaid, Terence M. Hogan, Leah J. Zell,
Marcel P. Houtzager and Robert A. Mohn, who are officers of the Trust, are
principals of WAM.  WAM has approximately $5.6 billion under management.

                                  Distributor

     Shares of each fund are distributed by WAM Brokerage Services, L.L.C. ("WAM
BD") under a Distribution Agreement as described in the prospectus dated April
30, 1997, which is incorporated herein by reference.  The Distribution Agreement
continues in effect from year to year, provided such continuance is approved
annually (i) by a majority of the trustees or by a majority of the outstanding
voting securities of the Trust, and (ii) by a majority of the trustees who are
not parties to the Agreement or interested persons of any such party.  The Trust
has agreed to pay all expenses in connection with registration of its shares
with the Securities and Exchange Commission and any auditing and filing fees
required in compliance with various state securities laws.  WAM bears all sales
and promotional expenses, including the cost of prospectuses and other materials
used for sales and promotional purposes by WAM BD.

                                       25
<PAGE>
 
     As agent, WAM BD offers shares of each fund to investors in states where
the shares are qualified for sale, at net asset value without sales commissions
or other sales loads to the investor.  In addition, no sales commission or "12b-
1" payment is paid by the funds.  WAM BD offers the funds' shares only on a best
efforts basis.

                                   The Trust

     The Declaration of Trust may be amended by a vote of either the Trust's
shareholders or its trustees.  The Trust may issue an unlimited number of
shares, in one or more series as the board of trustees may authorize.  Any such
series of shares may be further divided, without shareholder approval, into two
or more classes of shares having such preferences or special or relative rights
or privileges as the trustees may determine.  The shares of the funds are not
currently divided into classes.  Acorn Fund, Acorn International and Acorn USA
are the only series of the Trust currently being offered.  The board of trustees
may authorize the issuance of additional series if deemed advisable, each with
its own investment objective, policies, and restrictions.  All shares issued
will be fully paid and non-assessable and will have no preemptive or conversion
rights.

     On any matter submitted to a vote of shareholders, shares are voted in the
aggregate and not by individual series except that shares are voted by
individual series when required by the Investment Company Act of 1940 or other
applicable law, or when the board of trustees determines that the matter affects
only the interests of one series, in which case shareholders of the unaffected
series are not entitled to vote on such matters.  All shares of the Trust are
voted together in the election of trustees.

                             Trustees and Officers

     The trustees and officers of the Trust and their ages and principal
business activities during the past five years are:

Irving B. Harris, trustee and chairman
     Two North LaSalle Street, Chicago, Illinois 60602; age 86; chairman of the
     executive committee and director, Pittway Corporation (multi-product
     manufacturer and publisher); chairman, William Harris Investors, Inc.
     (investment adviser); chairman, The Harris Foundation (charitable
     foundation); director, Teva Pharmaceutical Industries, Inc. (pharmaceutical
     manufacturer)

Ralph Wanger, trustee and president*
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 62;
     trustee and president, Wanger Advisors Trust; principal, Wanger Asset
     Management, L.P. since July 1992; prior thereto, principal, Harris
     Associates L.P.

James H. Lorie, trustee and vice chairman
     1101 East 58th Street, Chicago, Illinois 60637; age 74; retired; Eli B. and
     Harriet B. Williams Professor of Business Administration Emeritus,
     University of Chicago Graduate School of Business; director, Ardco, Inc.
     (refrigeration equipment

                                       26
<PAGE>
 
     manufacturer); director, Thornburg Mortgage Asset Corp. (REIT) and Santa Fe
     Natural Tabacco

Leo A. Guthart, trustee
     165 Eileen Way, Syosset, New York 11791; age 58; vice chairman, Pittway
     Corporation (multi-product manufacturer and publisher); chief executive
     officer, Pittway Corporation's Security Group of Companies which include
     ADEMCO (manufacturer of alarm equipment), ADI (distributor of security
     equipment), Fire Burglary Instruments (supplier of security control
     panels), First Alert Professional (alarm dealers), Cylink Corporation
     (supplier of encryption equipment), and Alarm Net (cellular radio service);
     director, AptarGroup, Inc. (producer of dispensing valves, pumps and
     closures); director, Cylink Corporation; chairman of the board of trustees,
     Hofstra University; chairman, Tech Transfer Island Corp. (private
     investment partnership); director, Long Island Research Institute
    
Jerome Kahn, Jr., trustee
     Two North LaSalle Street, Suite 400, Chicago, Illinois 60602; age 62; vice
     president, William Harris Investors, Inc. (investment adviser); director,
     Pittway Corporation (multi-product manufacturer and publisher)     

David C. Kleinman, trustee
     1101 East 58th Street, Chicago, Illinois 60637; age 60; senior lecturer in
     business administration, University of Chicago Graduate School of Business;
     business consultant; director, Irex Corporation (insulation contractor)

Charles P. McQuaid, trustee and senior vice president*
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 43;
     trustee and senior vice president, Wanger Advisors Trust; principal, Wanger
     Asset Management, L.P. since July 1992; prior thereto, principal, Harris
     Associates L.P.
    
Roger S. Meier, trustee
     1211 S. W. Fifth Avenue, Portland, Oregon 97204; age 70; president, AMCO,
     Inc. (investment and real estate management); director, Fred Meyer, Inc.
     (retail chain); director, Red Lion Inns Limited Partnership (hotel chain);
     director, Key Bank of Oregon (banking); chairman of Investment Council and
     member of Committee of Legacy Systems (hospital); executive director and
     chairman of investment committee, Portland Art Museum    

Adolph Meyer, Jr., trustee
     1511 West Webster Avenue, Chicago, Illinois 60614; age 72; president, Gulco
     Corp. (leather manufacturer)

Malcolm N. Smith, trustee (resigned during 1996)
     309 Maple Avenue, Highland Park, Illinois 60035; age 75; president, Newmac,
     Inc. (importers of Sheffield cutlery); prior thereto, president, Macromatic
     Division, Milwaukee Electronics Corporation (electronic timing devices
     manufacturer)

Terence M. Hogan, vice president
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 34; vice
     president, 

                                       27
<PAGE>
 
Leah J. Zell, vice president
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 47; vice
     president, Wanger Advisors Trust; principal, analyst, and portfolio
     manager, Wanger Asset Management, L.P., since July 1992; prior thereto,
     analyst, Harris Associates L.P.
    
Marcel P. Houtzager, vice president
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 36;
     principal and investment analyst, Wanger Asset Management, L.P. since April
     1992 

Robert A. Mohn, vice president
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 35;
     principal, analyst and portfolio manager, Wanger Asset Management, L.P.
     since August 1992    

Merrillyn J. Kosier, vice president and secretary
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 36; vice
     president and secretary, Wanger Advisors Trust; director of marketing and
     shareholder services, Wanger Asset Management, L.P., since September 1993;
     prior thereto, vice president of marketing, Kemper Financial Services, Inc.

Bruce H. Lauer, vice president and treasurer
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60606; age 39; vice
     president and treasurer, Wanger Advisors Trust; chief administrative
     officer, Wanger Asset Management, L.P. since April 1995; prior thereto,
     first vice president, investment accounting, Kemper Financial Services,
     Inc.

Kenneth A. Kalina, assistant treasurer
     227 West Monroe Street, Suite 3000, Chicago, Illinois 60603; age 37;
     assistant treasurer, Wanger Advisors Trust; Fund controller, Wanger Asset
     Management, L.P., since September 1995; prior thereto, treasurer of the
     Stein Roe Mutual Funds

     *Messrs. McQuaid and Wanger are trustees who are interested persons of
Acorn as defined in the Investment Company Act of 1940, and of WAM.  Messrs.
Harris, Lorie, and Wanger are members, and Mr. McQuaid is an alternate member,
of the executive committee, which has authority during intervals between
meetings of the board of trustees to exercise the powers of the board, with
certain exceptions.
    
     At March 31, 1997 the trustees and officers as a group had the power to 
vote or dispose of 3,595,385 shares (1.88% of the outstanding shares) of Acorn 
Fund; 1,233,214 shares (1.32% of the outstanding shares) of Acorn International;
and 1,008,242 shares (13.32% of the outstanding shares) of Acorn USA.  Of these 
shares, the trustees and officers disclaimed beneficial ownership in the 
following numbers of shares; 2,413,102 shares of Acorn Fund (1.26% of the 
outstanding shares); 999,997 shares of Acorn International (1.07% of the 
outstanding shares); and 433,001 shares of Acorn USA (5.72% of the outstanding 
shares). The Illinois Deferred Compensation Plan held 16,331,111 shares of Acorn
Fund (8.55% of the outstanding shares).  Charles Schwab & Co., Inc. held 
13,317,126 shares of Acorn International (14.23% of the outstanding shares) as 
holder of record, but not beneficially.  National Financial Service held 940,443
shares of Acorn USA (12.4% of the outstanding shares) as holder of record, but 
not beneficially.  During 1996 the funds paid fees aggregating $216,000 to board
members who were not affiliated with WAM.     
         

                                      28
<PAGE>
 

     The following table sets forth the total compensation paid by the Trust 
during the fiscal year ended December 31, 1996 to each of the trustees of the 
trust. The trust has no retirement or pension plan. The officers and trustees 
affiliated with WAM serve without any compensation from the Trust.


<TABLE>
<CAPTION>

                                       Aggregate      Aggregate         Aggregate           Total
                                      Compensation  Compensation       Compensation      Compensation
Name of Trustee                        from Acorn    from Acorn         from Acorn           from
                                          Fund      International          USA           Fund Complex
- -----------------------------------------------------------------------------------------------------

<S>                                   <C>           <C>                <C>               <C>
Irving B. Harris                        $43,197        $35,595              $208         $81,000

Leo A. Guthart                            9,965          8,480                55          18,500

Jerome Kahn, Jr.                         10,965          9,480                55          20,500

David C. Kleinman                        11,280          9,660                60          21,000

James H. Lorie                            9,465          7,980                55          17,500

Charles P. McQuaid                            0              0                 0               0

Roger S. Meier                           10,215          8,730                55          19,000

Adolph Meyer, Jr.                         9,650          8,300                50          18,000

Malcolm N. Smith /4/                     10,965          9,480                55          20,500

Ralph Wanger                                  0              0                 0               0
- -----------------------------------------------------------------------------------------------------
</TABLE>

                        Purchasing and Redeeming Shares

     Purchases and redemptions are discussed in the funds' prospectus under the
headings "How to Buy Shares," "How to Sell Shares," and "Transaction Services."
All of that information is incorporated herein by reference.

     For purposes of computing the net asset value of a share of either fund, a
security traded on a securities exchange, or in an over-the-counter market in
which transaction prices are reported, is valued at the last sales price at the
time of valuation.  A security for which there is no reported sale on the
valuation date is valued at the mean of the latest bid and ask quotations or, if
there is no ask quotation, at the most recent bid quotation.  Securities for
which quotations are not available and any other assets are valued at a fair
value as determined in good faith by the 

/4/ At December 31, 1996, Mr. Smith had resigned his position as a trustee.

                                       29
<PAGE>
 
board of trustees. Money market instruments having a maturity of 60 days or less
from the valuation date are valued on an amortized cost basis. All assets and
liabilities initially expressed in foreign currencies are converted into U.S.
dollars at the mean of the bid and offer prices of such currencies against U.S.
dollars quoted by any major bank or dealer. If such quotations are not
available, the rate of exchange will be determined in accordance with policies
established in good faith by the board of trustees.

     The funds' net asset values are determined only on days on which the New
York Stock Exchange ("NYSE") is open for trading.  The NYSE is regularly closed
on Saturdays and Sundays and on New Year's Day, the third Monday in February,
Good Friday, the last Monday in May, Independence Day, Labor Day, Thanksgiving,
and Christmas.  If one of these holidays falls on a Saturday or Sunday, the NYSE
will be closed on the preceding Friday or the following Monday, respectively.

     Trading in the portfolio securities of the funds may take place in various
foreign markets on certain days (such as Saturday) when the funds are not open
for business and do not calculate their net asset values.  Conversely, trading
in the funds' portfolio securities may not occur on days when the funds are
open.  Therefore, the calculation of net asset value does not take place
contemporaneously with the determinations of the prices of many of the funds'
portfolio securities and the value of the funds' portfolios may be significantly
affected on days when shares of the funds may not be purchased or redeemed.

     Computation of net asset value (and the sale and redemption of fund shares)
may be suspended or postponed during any period when (a) trading on the NYSE is
restricted, as determined by the Securities and Exchange Commission, or that
exchange is closed for other than customary weekend and holiday closings, (b)
the Commission has by order permitted such suspension, or (c) an emergency, as
determined by the Commission, exists making disposal of portfolio securities or
valuation of the net assets of the funds not reasonably practicable.

     Acorn has elected to be governed by Rule 18f-1 under the Investment Company
Act of 1940 pursuant to which it is obligated to redeem shares solely in cash up
to the lesser of $250,000 or 1% of the net asset value of a fund during any 90-
day period for any one shareholder.  Redemptions in excess of the above amounts
will normally be paid in cash, but may be paid wholly or partly by a
distribution in kind of securities.  If a redemption is made in kind, the
redeeming shareholder would bear any transaction costs incurred in selling the
securities received.

     Due to the relatively high cost of maintaining smaller accounts, Acorn
reserves the right to redeem shares in any account for their then-current value
(which will be promptly paid to the investor) if at any time the shares in the
account do not have a value of at least $1,000.  An investor will be notified
that the value of his account is less than that minimum and allowed at least 30
days to bring the value of the account up to at least $1,000 before the
redemption is processed.  The Agreement and Declaration of Trust also authorizes
Acorn to redeem shares under certain other circumstances as may be specified by
the board of trustees.

                                      30
<PAGE>
 
     In connection with the Switch Plan, WAM acts as a shareholder servicing
agent for the Reich & Tang Money Funds ("Money Funds").  For its services it
receives a fee at the rate of 0.35% of the average annual net assets of each
account in a Money Fund established through the Switch Plan, pursuant to a 12b-1
plan adopted by the Money Funds.

                          Additional Tax Information

     Each fund intends to continue to qualify to be taxed as a regulated
investment company under Subchapter M of the Internal Revenue Code (the "Code")
so as to be relieved of federal income tax on its capital gains and net
investment income currently distributed to its shareholders.

     At the time of your purchase, a fund's net asset value may reflect
undistributed income, capital gains, or net unrealized appreciation of
securities held by that fund.  A subsequent distribution to you of such amounts,
although constituting a return of your investment, would be taxable either as a
dividend or capital gain distribution.

     Foreign currency gains and losses, including the portion of gain or loss on
the sale of debt securities attributable to foreign exchange rate fluctuations,
are taxable as ordinary income.  If the net effect of these transactions is a
gain, the income dividend paid by a fund will be increased; if the result is a
loss, the income dividend paid by a fund will be decreased.

     Dividends paid by Acorn International are not eligible for the dividends-
received deduction for corporate shareholders, if as expected, none of that
fund's income consists of dividends paid by United States corporations.  A
portion of the dividends paid by Acorn Fund and Acorn USA is expected to be
eligible for the dividends-received deduction.  Capital gain distributions paid
from the funds are never eligible for this deduction.

     Income received by the funds from sources within various foreign countries
will be subject to foreign income taxes withheld at the source.  Under the Code,
if more than 50% of the value of a fund's total assets at the close of its
taxable year comprises securities issued by foreign corporations, that fund may
file an election with the Internal Revenue Service to "pass through" to its
shareholders the amount of foreign income taxes paid by that fund.  Pursuant to
this election, shareholders will be required to: (i) include in gross income,
even though not actually received, their respective pro rata share of foreign
taxes paid by the fund; (ii) treat their pro rata share of foreign taxes as paid
by them; and (iii) either deduct their pro rata share of foreign taxes in
computing their taxable income, or use it as a foreign tax credit against U.S.
income taxes (but not both).  No deduction for foreign taxes may be claimed by a
shareholder who does not itemize deductions.

     Acorn International intends to meet the requirements of the Code to "pass
through" to its shareholders foreign income taxes paid, but there can be no
assurance that it will be able to do so.  Each shareholder will be notified
within 60 days after the close of each taxable year of Acorn International, if
the foreign taxes paid by the fund will "pass through" for that year, and, if
so, the amount of each shareholder's pro rata share (by country) of (i) the
foreign taxes paid, and (ii) Acorn International's gross income from foreign
sources.  Of course, shareholders who 


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<PAGE>
 
are not liable for federal income taxes, such as retirement plans qualified
under Section 401 of the Code, will not be affected by any such "pass through"
of foreign tax credits. Acorn Fund and Acorn USA do not expect to be able to
"pass through" foreign tax credits.

                        Taxation of Foreign Shareholders

     The Code provides that dividends from net income, which are deemed to
include for this purpose each shareholder's pro rata share of foreign taxes paid
by Acorn International (see discussion of "pass through" of the foreign tax
credit to U.S. shareholders), will be subject to U.S. tax.  For shareholders who
are not engaged in a business in the U.S., this tax would be imposed at the rate
of 30% upon the gross amount of the dividend in the absence of a Tax Treaty
providing for a reduced rate or exemption from U.S. taxation.  Distributions of
net long-term capital gains are not subject to tax unless the foreign
shareholder is a nonresident alien individual who was physically present in the
U.S. during the tax year for more than 182 days.

                             Portfolio Transactions

     Portfolio transactions of the funds are placed with those securities
brokers and dealers that WAM believes will provide the best value in transaction
and research services for each fund, either in a particular transaction or over
a period of time.  Although some transactions involve only brokerage services,
many involve research services as well.

     In valuing brokerage services, WAM makes a judgment as to which brokers are
capable of providing the most favorable net price (not necessarily the lowest
commission) and the best execution in a particular transaction.  Best execution
connotes not only general competence and reliability of a broker, but specific
expertise and effort of a broker in overcoming the anticipated difficulties in
fulfilling the requirements of particular transactions, because the problems of
execution and the required skills and effort vary greatly among transactions.

     In valuing research services, WAM makes a judgment of the usefulness of
research and other information provided to WAM by a broker in managing each
fund's investment portfolio.  In some cases, the information, e.g., data or
recommendations concerning particular securities, relates to the specific
transaction placed with the broker, but for the greater part the research
consists of a wide variety of information concerning companies, industries,
investment strategy, and economic, financial, and political conditions and
prospects, useful to WAM in advising that fund.

     The reasonableness of brokerage commissions paid by the funds in relation
to transaction and research services received is evaluated by WAM's staff on an
ongoing basis.  The general level of brokerage charges and other aspects of each
fund's portfolio transactions are reviewed periodically by the board of trustees
and its committee on portfolio transactions.

     WAM is the principal source of information and advice to the funds, and is
responsible for making and initiating the execution of investment decisions by
the funds.  However, the board of trustees recognizes that it is important for
WAM, in performing its responsibilities to the funds, to continue to receive and
evaluate the broad spectrum of economic and financial 


                                      32
<PAGE>
 
information that many securities brokers have customarily furnished in
connection with brokerage transactions, and that in compensating brokers for
their services, it is in the interest of the funds to take into account the
value of the information received for use in advising the funds. The extent, if
any, to which the obtaining of such information may reduce WAM's expenses in
providing management services to the funds is not determinable. In addition, the
board of trustees understands that other clients of WAM might benefit from the
information obtained for the funds, in the same manner that the funds might
benefit from information obtained by WAM in performing services to others.

     Transactions of the funds in the over-the-counter market and the third
market are executed with primary market makers acting as principal except where
it is believed that better prices and execution may be obtained otherwise.
    
     Brokerage commissions incurred by Acorn Fund for 1996, 1995, and 1994
aggregated approximately $3,440,000, $2,565,000, and $1,870,000, respectively,
not including the gross underwriting spread on securities purchased in
underwritten public offerings. During 1996 Acorn Fund paid brokerage commissions
aggregating approximately $2,435,000 in connection with portfolio transactions
involving purchases and sales aggregating approximately $822 million to brokers
who furnished investment research services to the fund.      
    
     Brokerage commissions incurred by Acorn International for 1996, 1995, and
1994 aggregated approximately $3,929,000, $3,113,000, and $3,775,000,
respectively, not including the gross underwriting spread on securities
purchased in underwritten public offerings. In 1996 Acorn International paid
brokerage commissions aggregating approximately $3,614,000 in connection with
portfolio transactions involving purchases and sales aggregating approximately
$910 million to brokers who furnished investment research services to the fund.
     
     Brokerage commissions incurred by Acorn USA  in 1996 totalled $88,900,
not including the gross underwriting spread on securities purchased in
underwritten public offerings.  In 1996 Acorn USA paid brokerage commissions
aggregating approximately $47,400 in connection with portfolio transactions
involving purchases and sales aggregating approximately $15 million to brokers
who furnished investment research services to the fund.      

     Although investment decisions for the funds are made independently from
those for other investment advisory clients of WAM, it may develop that the same
investment decision is made for one or both of the funds and one or more other
advisory clients.  If one or both of the funds and other clients purchase or
sell the same class of securities on the same day, the transactions will be
allocated as to amount and price in a manner considered equitable to each.

                                   Custodian

     State Street Bank and Trust Company, P.O. Box 8502, Boston Massachusetts
02266-8502, is the custodian for the funds.  It is responsible for holding all
securities and cash of the funds, receiving and paying for securities purchased,
delivering against payment securities sold, receiving and collecting income from
investments, making all payments covering expenses of the funds, and performing
other administrative duties, all as directed by authorized persons of the 


                                      33
<PAGE>
 
funds. The custodian does not exercise any supervisory function in such matters
as purchase and sale of portfolio securities, payment of dividends, or payment
of expenses of the funds. The funds have authorized the custodian to deposit
certain portfolio securities of the funds in central depository systems as
permitted under federal law. The funds may invest in obligations of the
custodian and may purchase or sell securities from or to the custodian.

                              Independent Auditors

     Ernst & Young LLP, Sears Tower, 233 South Wacker Drive, Chicago, Illinois
60606 audits and reports on the funds' annual financial statements, reviews
certain regulatory reports and the funds' tax returns, and performs other
professional accounting, auditing, tax, and advisory services when engaged to do
so by the funds.


                                      34
<PAGE>
 
                     Appendix - Description of Bond Ratings

     A rating of a rating service represents the service's opinion as to the
credit quality of the security being rated.  However, the ratings are general
and are not absolute standards of quality or guarantees as to the
creditworthiness of an issuer. Consequently, WAM believes that the quality of
debt securities in which the funds invest should be continuously reviewed.  A
rating is not a recommendation to purchase, sell or hold a security, because it
does not take into account market value or suitability for a particular
investor.  When a security has received a rating from more than one service,
each rating should be evaluated independently.  Ratings are based on current
information furnished by the issuer or obtained by the ratings services from
other sources which they consider reliable.  Ratings may be changed, suspended
or withdrawn as a result of changes in or unavailability of such information, or
for other reasons.

     The following is a description of the characteristics of ratings used by
Moody's Investors Service, Inc. ("Moody's") and Standard & Poor's Corporation
("S&P").

Moody's Ratings

     Aaa--Bonds 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.  Although 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 bonds.

     Aa--Bonds rated Aa are judged to be 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 bonds or fluctuation of protective elements may be
of greater amplitude or there may be other elements present which make the long
term risk appear somewhat larger than in Aaa bonds.

     A--Bonds 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.

     Baa--Bonds 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.

     Ba--Bonds rated Ba are judged to have speculative elements; their future
cannot be considered as well assured.  Often the protection of interest and
principal payments may be very moderate and thereby not well safeguarded during
both good and bad times over the future.  Uncertainty of position characterizes
bonds in this class.


                                      35
<PAGE>
 
     B--Bonds rated B generally lack characteristics of the desirable
investment.  Assurance of interest and principal payments or of maintenance of
other terms of the contract over any long period of time may be small.

     Caa--Bonds rated Caa are of poor standing.  Such bonds may be in default or
there may be present elements of danger with respect to principal or interest.

     Ca--Bonds rated Ca represent obligations which are speculative in a high
degree.  Such bonds are often in default or have other marked shortcomings.

S&P Ratings
     AAA--Bonds rated AAA have the highest rating.  Capacity to pay principal
and interest is extremely strong.

     AA--Bonds rated AA have a very strong capacity to pay principal and
interest and differ from AAA bonds only in small degree.

     A--Bonds rated A have a strong capacity to pay principal and interest,
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
principal and interest.  Whereas they normally exhibit protection parameters,
adverse economic conditions or changing circumstances are more likely to lead to
a weakened capacity to pay principal and interest for bonds in this capacity
than for bonds in higher rated categories.

     BB--B--CCC--CC--Bonds rated BB, B, CCC and CC are regarded, on balance, as
predominantly speculative with respect to the issuer's capacity to pay interest
and repay principal in accordance with the terms of the obligation.  BB
indicates the lowest degree of speculation among such bonds and CC the highest
degree of speculation.  Although such bonds will likely have some quality and
protective characteristics, these are outweighed by large uncertainties or major
risk exposures to adverse conditions.


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