GATEWAY TRUST
485BPOS, 2000-05-01
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<PAGE>   1
        As filed with the Securities and Exchange Commission on November 2, 1998
                                 Securities Act Of 1933 Registration No. 2-59895
                       Investment Company Act of 1940 Registration No. 811-02773

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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933                  [ ]
                      Pre-Effective Amendment No. _____                  [ ]

                      Post-Effective Amendment No. 35                    [X]


                                       and

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940          [ ]

                                Amendment No. 33                         [X]


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                                THE GATEWAY TRUST
                        400 TechneCenter Drive, Suite 220
                               Milford, Ohio 45150
                         Telephone Number (513) 248-2700

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      Agent for Service:                       Copy to:
      WALTER G. SALL                           Donald S. Mendelsohn, Esq..
      400 TechneCenter Drive, Suite 220        Brown, Cummins & Brown Co. L.P.A.
      Milford, Ohio 45150                      441 Vine Street
                                               Cincinnati, Ohio 45202

It is proposed that this filing will become effective (check the appropriate
box)

[ ] immediately upon filing pursuant to paragraph (b)

[X] on May 1, 2000 pursuant to paragraph (b)

[ ] 60 days after filing pursuant to paragraph (a)(1)
[ ] on (date) pursuant to paragraph (a)(1)
[ ] 75 days after filing pursuant to paragraph (a)(2)
[ ] on (date) pursuant to paragraph (a)(2) of Rule 485

If appropriate, check the following box:

[ ] this post-effective amendment designates a new effective date for a
previously filed post-effective amendment.

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<PAGE>   2

FRONT COVER


Gateway Fund


PROSPECTUS May 1, 2000



As with all mutual funds, the Securities and Exchange Commission has not
determined that the information in this prospectus is accurate or complete, nor
has it approved or disapproved the Fund's shares. It is a criminal offense to
state otherwise.


The Gateway Trust



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<TABLE>
<CAPTION>

                                TABLE OF CONTENTS
<S>                                                                                 <C>
Gateway Fund Investment Objective and Principal Strategies............................3
Principal Risks.......................................................................3
Past Performance......................................................................3
Expenses..............................................................................5
   Annual Fund Operating Expenses.....................................................5
   Example............................................................................5
   Management Fees....................................................................5
   Distribution (12b-1) Fees..........................................................5
   Other Expenses.....................................................................6
More Information about Principal Investment Strategies and Risks......................6
   Principal Investment Strategies....................................................6
   Risks..............................................................................7
About the Investment Adviser..........................................................7
   Portfolio Manager Profile..........................................................7
Other Information.....................................................................7
   How Fund Shares Are Priced.........................................................7
   Dividends and Distributions........................................................8
   Tax Issues.........................................................................8
Financial Highlights..................................................................9
Investing Through a Financial Professional...........................................10
Investing Directly...................................................................10
   Opening Your Account..............................................................10
   Additional Investments............................................................10
How To Redeem Your Shares............................................................11
Additional Information about Purchasing and Redeeming Shares.........................12
</TABLE>



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<PAGE>   4

GATEWAY FUND INVESTMENT OBJECTIVE AND PRINCIPAL STRATEGIES
The investment objective of the Gateway Fund is to capture the majority of the
higher returns associated with equity market investments, while exposing
investors to significantly less risk than other equity investments.
Historically, investments in equities have produced higher rates of return than
fixed income investments. While providing higher returns, equity investments
tend toward greater fluctuations in value over time, thus being significantly
more volatile than fixed income investments. The Fund undertakes active measures
to reduce equity volatility while investing almost all of its assets in
equities.


The Fund is designed for you if you are a conservative investor whose investment
objective is to earn consistently higher rates of return than fixed income
investments over the long term. The Fund owns the 500 common stocks included in
the S&P 500 Index, and sells index call options on its indexed portfolio.
Selling index call options reduces the Fund's volatility, provides a steady cash
flow, and is the Fund's primary source of return. The Fund also buys index put
options that can protect the Fund from a significant market decline over a short
period of time. The value of a put option generally increases as stock prices
decrease. The combination of the indexed stock portfolio, the steady cash flow
from the sale of index call options, and the downside protection from index put
options is designed to provide the Fund with fairly consistent returns over a
wide range of fixed income and equity market environments.






The Fund not only strives for consistent returns, but also returns in excess of
those available from other investments comparable in volatility. Historically,
two types of investments have had volatility comparable to the Fund -
intermediate-term fixed income investments (approximately five-year maturities)
and hybrid investments containing a blend of short-term fixed income and equity
investments. With its core investment in equities, the Fund is significantly
less vulnerable to fluctuations in value caused by interest rate volatility, a
risk factor present in both fixed income and hybrid investments. The objective
of the risk management strategy using index options is to limit the volatility
inherent in equities while sacrificing less of the higher equity returns than
hybrid investments. Thus, the Fund seeks to provide an efficient trade-off
between risk and reward where risk is characterized by volatility or
fluctuations in value over time.


PRINCIPAL RISKS

The Fund's stock portfolio is subject to market risk. Stock prices may decline
over short or even extended periods of time. The Fund's option strategies may
not fully protect it against declines in the value of its stock portfolio. The
Fund could experience a loss in both the stock and option portions of its
portfolio.

When it sells index call options, the Fund receives cash but limits its
opportunity to profit from an increase in the market value of its stock
portfolio. When the Fund purchases index put options, it risks the loss of the
cash paid for the options. Under certain circumstances the Fund may not own any
put options, resulting in increased risk during a market decline.



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<PAGE>   5

The value of your investment in the Fund may go up and down. You could lose
money investing in the Fund. Furthermore, because the Fund has a long-term
investment objective, it is not appropriate for short-term investments.


PAST PERFORMANCE
The bar chart and table below show the variability of the Fund's returns, which
is one indicator of the risks of investing in the Fund. As with all mutual
funds, historical results do not necessarily indicate how the Fund will perform
in the future. The bar chart shows the Fund's annual total returns for each of
the last ten years and how returns can fluctuate from year to year. All return
figures on this page assume the reinvestment of dividends and distributions.
Also shown are the best and worst quarterly returns for the Fund over the same
time period.

(Insert Bar Chart)

(Plot Points for Bar Chart)
Gateway Fund

Annual Total Returns as of December 31,
1990            10.26%
1991            17.79%
1992             5.14%
1993             7.40%
1994             5.57%
1995            11.04%
1996            10.53%
1997            12.35%
1998            12.26%
1999            12.97%



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BEST QUARTER - FOURTH QUARTER 1990                         8.95%
WORST QUARTER - THIRD QUARTER 1990                         4.62%

The following table compares the Fund's performance over time to that of the S&P
500 Index, the Lehman Government/Corporate Bond Index, the Salomon Broad
Investment-Grade Medium-Term (1-10) Index, and the Russell 2000 Index. The S&P
500 and Russell 2000 indexes are popular indicators of the performance of the
large and small capitalization sectors, respectively, of the U. S. stock market.
These indexes were chosen for comparison because they reflect the broad spectrum
of U. S. equity markets. The Lehman Government/Corporate Bond Index and the
Salomon Broad Investment-Grade Medium-Term (1-10) Index both reflect the
performance of the U. S. bond market and were chosen for comparison because
their historical risk characteristics are similar to those of the Fund. The
Salomon Broad Investment-Grade Medium-Term (1-10) Index will replace the Lehman
Government/Corporate Bond Index in future comparative performance information
for the Fund because historical information for the Salomon index is included in
the performance database software available to the Fund, and historical
information for the Lehman index is not.




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                          AVERAGE ANNUAL TOTAL RETURNS
                             AS OF DECEMBER 31, 1999

                                              ---------------------------------
                                                 1 YEAR    5 YEARS  10 YEARS
                                              ---------------------------------

Gateway Fund                                      12.97%   11.82%    10.47%
Salomon Broad Investment-Grade Medium-Term         1.00     7.42      7.51
(1-10) Index
S&P 500 Index                                     21.01    28.49     18.17
Lehman Gov't./Corp Bond Index                     -1.76     7.69      7.70
Russell 2000 Index                                21.26    16.69     13.40




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<PAGE>   7


EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that are deducted from Fund assets)


Management Fees                              0.61%
Distribution (12b-1) Fees                    0.31
Other Expenses                               0.06
                                             ----
Total Annual Fund Operating Expenses         0.98%



EXAMPLE
This Example helps you compare the cost of investing in the Fund with the cost
of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods
indicated and then redeem all of your shares at the end of those periods. The
Example also assumes that your investment has a 5% return each year and that the
Fund's operating expenses remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:


     1 Year          3 Years        5 Years        10 Years
- ---------------------------------------------------------------
      $100            $312            $542          $1,201


MANAGEMENT FEES

The Fund paid the Adviser a fee of 0.61% of its average net assets for the 1999
fiscal year. This fee reflects the terms of the Management Agreement under which
the Adviser is paid 0.925% of the average value of the daily net assets of the
Fund minus the amount of the Fund's expenses incurred pursuant to its
Distribution Plan. Also under the Management Agreement, the Adviser receives no
separate fee for its transfer agency, fund accounting, and other services to the
Fund, and the Adviser pays the Fund's expenses of reporting to shareholders.


DISTRIBUTION (12B-1) FEES

The Fund has adopted a plan under Rule 12b-1 of the Investment Company Act that
allows it to pay for the sale and distribution of its shares. The Trustees of
The Gateway Trust review and approve expenses under the plan. In any year,
distribution expenses cannot exceed 0.50% of the average daily net asset value
of the Fund. For 1999, expenses under the plan were 0.31% of the average daily
net asset value of the Fund. The Management Fees paid to the Adviser are reduced
dollar for dollar by the Fund's distribution expenses, so the distribution
expenses do not increase the cost of your investment in the Fund.


OTHER EXPENSES
The Fund pays all of its normal operating expenses, including: custodial fees,
registration of Fund shares with federal and state securities agencies, and the
Fund's share of general expenses of The Gateway Trust (the "Trust"). The Fund
also reimburses the Adviser for compliance expenses. The Adviser pays certain
expenses of the Fund including: printing and distributing all Fund prospectuses
and reports to current shareholders,



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<PAGE>   8

printing and transmitting registration statements and reports to governmental
agencies, and printing and mailing costs.

MORE INFORMATION ABOUT PRINCIPAL INVESTMENT STRATEGIES AND RISKS

PRINCIPAL INVESTMENT STRATEGIES

PURCHASING STOCKS

The Fund invests in the 500 stocks included in the S&P 500 Index. Each stock is
held in approximately the same proportion as in the S&P 500. For example, if a
stock represents 2% of the value of the S&P 500, the Fund invests approximately
2% of its assets in the stock. The Adviser monitors the composition of the S&P
500 and makes adjustments to the Fund's portfolio as needed.

"Standard & Poor's(R)", "S&P(R)", "S&P 500(R)", and "Standard & Poor's 500" and
"500" are trademarks of The McGraw-Hill Companies, Inc. and have been licensed
for use by The Gateway Trust. The Fund is not sponsored, endorsed, sold, or
promoted by Standard & Poor's and Standard and Poor's makes no representation
regarding the advisability of investing in the Fund.

Please see the Fund's Statement of Additional Information for more information.


SELLING INDEX CALL OPTIONS

The Fund continuously sells index call options on the full value of its indexed
stock portfolio. As the seller of the index call option, the Fund receives cash
(the "premium") from the purchaser. The purchaser of an index call option has
the right to any appreciation in the value of the index over a fixed price (the
"exercise price") on a certain date in the future (the "expiration date"). If
the purchaser does not exercise the option, the Fund retains the premium. If the
purchaser exercises the option, the Fund pays the purchaser the difference
between the price of the index and the exercise price of the option. The
premium, the exercise price, and the market value of the index determine the
gain or loss realized by the Fund as the seller of the index call option. The
Fund can also repurchase the call option prior to the expiration date, ending
its obligation. In this case, the cost of repurchasing the option will determine
the gain or loss realized by the Fund.


PURCHASING INDEX PUT OPTIONS
The Fund buys index put options in an attempt to protect the Fund from a
significant market decline in a short period of time. The value of an index put
option generally increases as stock prices decrease. The Fund may not spend more
than 5% of its assets to purchase index put options.


OTHER INVESTMENTS
The Fund may hold cash for temporary defensive purposes, or under normal
circumstances for purposes of liquidity. Cash is normally invested in repurchase
agreements. In a repurchase agreement, the Fund buys securities and the seller
agrees at the time of sale to repurchase the securities at an agreed-upon date,
price, and interest rate. The Fund may not invest more than 5% of its assets in
repurchase agreements with a maturity longer than seven days. For temporary
defensive purposes, the Fund may hold up to 100% of its assets in cash. To the
extent that it is invested in cash for temporary defensive purposes, the Fund
would not achieve its investment objective.





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<PAGE>   9

RISKS


SELLING INDEX CALL OPTIONS
Selling call options reduces the risk of owning stocks, but it limits the
opportunity to profit from an increase in the market value of stocks in exchange
for up-front cash at the time of selling the call option.


PURCHASING INDEX PUT OPTIONS
The Fund risks losing all or part of the cash paid for purchasing index put
options.

CLOSING OPTION TRANSACTIONS
Unusual market conditions or the lack of a ready market for any particular
option at a specific time may reduce the effectiveness of the Fund's option
strategies.


ABOUT THE INVESTMENT ADVISER

Gateway Investment Advisers, L.P. (the "Adviser") has acted as the investment
adviser for the Gateway Fund since December 15, 1995. It is located at 400
TechneCenter Drive, Milford, Ohio 45150. The predecessor to the Adviser was
Gateway Investment Advisers, Inc. which provided the same services to the Fund
prior to December 15, 1995. As of December 31, 1999, the Adviser had
approximately $1.45 billion in assets under management, including approximately
$1 billion in assets invested in all of The Gateway Trust's mutual fund series.
The Adviser provides the Fund with investment research and advice, as well as
administration, accounting, transfer agency, and shareholder services. The fees
paid to the Adviser are shown in the expense table on page 7.

PORTFOLIO MANAGER PROFILE
J. Patrick Rogers, CFA
Portfolio Manager from 1997
Co-Portfolio Manager from 1994
MBA Xavier University 1994
BBA University of Notre Dame 1986
Age 36


J. Patrick Rogers, CFA, joined Gateway Investment Advisers, Inc., general
partner of Gateway Investment Advisers, L.P., in 1989 and has been its president
and a member of its board of directors since 1995. He is the portfolio manager
for the Gateway Fund as well as the Gateway Small Cap Index Fund and the
Cincinnati Fund(R). In addition, he is the president and a trustee of The
Gateway Trust.




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<PAGE>   10

OTHER INFORMATION

HOW FUND SHARES ARE PRICED
Your price for Fund shares is the Fund's net asset value per share (NAV), which
is ordinarily determined as of the close of the New York Stock Exchange (the
"NYSE"), normally 4:00 P.M. Eastern Time, on each day the NYSE is open. The NYSE
is not open on weekends, national holidays, or Good Friday. Your order will be
priced at the next NAV calculated after your request has been received in good
order as described below.


The Fund normally values stocks at market value and options at the average of
the closing bid and asked quotations. Under normal circumstances, closing option
quotations are considered to reflect the option contract values as of the stock
market close and will be used to value the option contracts. Securities for
which market quotations are not readily available, securities in which trading
has been suspended during the day, and all other assets are valued at fair
value. Furthermore, if the Adviser determines that closing options quotations do
not reflect option contract values as of the close of the NYSE, options are
valued at fair value. Fair value is determined in good faith under procedures
adopted by the Board of Trustees.



DIVIDENDS AND DISTRIBUTIONS
The Fund normally declares dividends and distributions of net capital gains at
the end of December. The capital gains distribution has varied considerably from
year to year. Unless otherwise instructed, dividends and capital gains are
reinvested in the Fund.


TAX ISSUES
The Fund distributes substantially all of its income and realized capital gains
and these distributions may be taxable to you. In addition, gains on any sale of
Fund shares including exchanges into other funds may be taxable to you.


If you buy Fund shares just before a distribution is declared, you will pay the
full price for the shares and then receive a portion of the price back as a
taxable distribution. The distribution paid to you would generally be included
in your gross income for tax purposes, whether or not you reinvested it. For
this reason, you should carefully consider the tax consequences of buying shares
of the Fund in late December.




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<PAGE>   11

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the Fund's
performance for the past five years. Certain information reflects results for a
single Fund share. The total returns in the table represent the rate an investor
would have earned (or lost) on an investment in the Fund, assuming reinvestment
of all dividends and distributions. This information has been audited by Arthur
Andersen LLP whose report, along with the Fund's financial statements, is
included in the Fund's annual report which is available on request.


<TABLE>
<CAPTION>


                                                                                YEAR ENDED DECEMBER 31,
                                                     -----------------------------------------------------------------------------
                                                         1999            1998            1997             1996          1995 (1)
                                                     -----------------------------------------------------------------------------
<S>                                                 <C>           <C>              <C>              <C>            <C>
  Net asset value, beginning of year                 $     21.02    $     18.85      $    18.48      $     16.91     $    15.48
  Net investment income                                     0.07           0.12            0.18             0.21           0.24
  Net gain on investments                                   2.65           2.18            2.09             1.56           1.46
                                                     -----------    -----------      ----------      -----------     ----------
    Total from investment operations                        2.72           2.30            2.27             1.77           1.70
                                                     -----------    -----------      ----------      -----------     ----------

  Dividends from net investment income                     (0.07)         (0.12)          (0.18)           (0.20)         (0.24)
  Distributions from net realized gain                        --          (0.01)          (1.72)              --             --
  Distributions in excess of net realized gain
                                                              --             --              --               --          (0.03)
                                                     -----------    -----------      ----------      -----------     ----------
      Total distributions                                  (0.07)         (0.13)          (1.90)           (0.20)         (0.27)
                                                     -----------    -----------      ----------      -----------     ----------
  Net asset value, end of year                       $     23.67    $     21.02      $    18.85      $     18.48     $    16.91
                                                     ===========    ===========      ==========      ===========     ==========

  TOTAL RETURN                                             12.97%         12.26%          12.35%           10.53%         11.04%

  Net assets, end of year (thousands)                $   922,128    $   464,200      $  255,458      $   194,363     $  176,220
  Ratio of expenses to average net assets                   0.98%          0.99%           1.07%            1.14%          1.19%
  Ratio of net investment income to
      average net assets                                    0.37%          0.66%           0.90%            1.18%          1.51%
  Portfolio turnover rate                                     11%            12%             82%              17%             5%
</TABLE>

(1)  On December 15, 1995, Gateway Investment Advisers, L.P. succeeded Gateway
     Investment Advisers, Inc. as investment adviser to the Fund.





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<PAGE>   12

INVESTING THROUGH A FINANCIAL PROFESSIONAL


You may purchase or sell Fund shares through a financial professional,
broker/dealer, bank or other financial institution, or an organization that
provides recordkeeping and consulting services to employee benefit plans (a
"Financial Institution"). A Financial Institution may charge you a fee for this
service and may require different minimum initial and subsequent investments
than if you invest in the Fund directly. Financial Institutions may also impose
other charges or restrictions different from those that apply to shareholders
who invest in the Fund directly. A Financial Institution, rather than its
customer, may be the shareholder of record of your shares. The Fund is not
responsible for the failure of any Financial Institution to carry out its
obligations to its customers. Certain Financial Institutions may receive
compensation from The Gateway Trust or its affiliates and they may receive
compensation from the Trust for shareholder recordkeeping and other services.
You should ask about any fees related to your investment in the Fund that are
not described in this Prospectus.



INVESTING DIRECTLY

Customer service representatives are available to assist you Monday through
Friday, from 8:30 A.M. to 5:30 P.M. Eastern Time, toll-free at (800) 354-6339.


OPENING YOUR ACCOUNT
The Gateway Fund is available for purchase by individuals in both taxable and
IRA accounts, as well as by corporations, trusts, and pension plans. After your
initial purchase and any subsequent transaction, you will receive a confirmation
statement showing the resulting value of your account.

OPENING A REGULAR (NON-IRA) ACCOUNT
To open a regular account in the Fund, please complete and sign a New Account
Application that accompanies this Prospectus. The minimum investment is $1,000.

OPENING AN IRA ACCOUNT
To open an IRA account, please complete and sign an IRA Account Application. The
minimum investment for an IRA is $500. If you have not received an IRA Account
Application and an IRA Agreement and Disclosure Statement, please call customer
service at (800) 354-6339. To transfer an existing IRA to the Gateway Fund, you
need to complete an IRA Transfer Form in addition to an IRA Account Application.
To transfer or roll over funds from an employer-sponsored plan such as a 401(k),
please call customer service at (800) 354-6339. You will find more detailed
information about transfers to and distributions from IRAs in the IRA Agreement
and Disclosure Statement.

BY MAIL
Please mail your Application (and IRA forms if needed), and a check for your
initial investment, payable to The Gateway Trust, to: The Gateway Trust,
Shareholder Services, P. O. Box 5211, Cincinnati, OH 45201-5211.

BY TELEPHONE
To open your account by telephone, you must wire your initial investment to The
Gateway Trust. If you buy shares through a wire transfer, Gateway will not
charge you for the wire. Your financial institution may charge you for this
service. Please call customer service at (800) 354-6339 for further
instructions.



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<PAGE>   13

ADDITIONAL INVESTMENTS
You may add to your Gateway Fund investment at any time. The minimum amount of
an additional investment is $100.

BY MAIL
Please mail an Additional Investment Form with your check. Additional Investment
Forms and business reply envelopes are included with most mailings you receive
from the Fund. All checks should be payable to The Gateway Trust.

BY TELEPHONE
To invest by telephone, you will need to wire your investment to the Fund.
Please call customer service at (800) 354-6339 for further information or to
place a purchase order. If money is wired without a purchase order, it will be
returned uninvested.

BY AUTOMATIC INVESTMENT PROGRAM
Our Automatic Investment Program is a convenient way to make regularly scheduled
investments in the Gateway Fund. When you use the program, funds are
electronically transferred from your bank account to Gateway and additional
shares are then purchased for your account. This service is available on a
monthly or quarterly basis with a minimum of $100 per transfer. Your financial
institution may charge you for transfers from your bank account to a Gateway
fund through the Automatic Investment Program. Please call customer service at
(800) 354-6339 for further instructions.

BY EXCHANGE FROM ANOTHER GATEWAY FUND
You may purchase shares by exchanging from another Gateway mutual fund. Please
call customer service at (800) 354-6339 for further instructions.


The Trust does not charge any fee for exchanges between Gateway funds.
Generally, an exchange between funds is a taxable event. State securities laws
may restrict your ability to make exchanges. The Trust reserves the right to
terminate, upon written notice, the exchange privilege for any shareholder who
makes an excessive number of exchanges between funds. The Trust also reserves
the right to terminate or modify the exchange privilege or to refuse an exchange
if the exchange would adversely affect any Gateway fund involved in the
exchange.



HOW TO REDEEM YOUR SHARES
You may redeem your Gateway Fund shares by choosing one of the following
options. The proceeds will be mailed or wired. Normally the proceeds will be
sent on the next business day. Payments to shareholders who have purchased
shares by check will not be made until the purchase check has cleared, which
could take up to fifteen days from the date of purchase. For information about
redeeming shares from an IRA, please call customer service at (800) 354-6339.

BY MAIL
You may send a written request to redeem shares to: The Gateway Trust,
Shareholder Services, P. O. Box 5211, Cincinnati, OH 45201-5211.

Your written request should specify the number of Fund shares or the dollar
amount to be redeemed. All owners must sign the request exactly as their names
appear on the account. In certain cases, other supporting legal documents may be
required. A check for the proceeds will be mailed to the address of record for
your account.



                                       12
<PAGE>   14

A signature guarantee is not usually required. However, a signature guarantee
may be required under certain circumstances. A signature guarantee is always
required if proceeds are to be paid to persons other than the record owner(s) of
the shares, or if the proceeds are to be sent to any address other than the
address of record for the account. An acceptable signature guarantee may be
obtained from banks, brokers, and certain other financial institutions. Notary
publics cannot guarantee your signature.

BY TELEPHONE
Unless you have declined telephone exchange and/or redemption privileges, you
may redeem your shares by calling customer service. Telephone redemptions are
not available for IRA accounts. If you redeem your shares by telephone, the
redemption proceeds can only be paid:
- -    by check to the owner(s) of the shares shown on Gateway's records and
     mailed to the address shown on Gateway's records for your account; or
- -    by wire if you completed the wire transfer instructions in your original
     New Account Application or you have sent separate wire transfer
     instructions. All owners must sign the request to establish wire transfer
     instructions exactly as their names appear on the account and the
     signatures must be guaranteed. If you redeem shares through a wire
     transfer, the Trust's custodian will assess a wire charge of $10. Your
     financial institution may also charge you for receiving a wire transfer of
     redemption proceeds.
The Gateway Trust will not be liable for any damages resulting from following
instructions received by telephone that it reasonably believes to be genuine.
The Trust will employ reasonable procedures to confirm that telephone
instructions are genuine.

SYSTEMATIC WITHDRAWAL PROGRAM
If the value of your account is at least $5,000, you can arrange for systematic
quarterly or monthly withdrawals in the amount of $100 or more. Please call
customer service at (800) 354-6339 to make arrangements to use this program.

ADDITIONAL INFORMATION ABOUT PURCHASING AND REDEEMING SHARES

- -    The Gateway Trust reserves the right to reject any investment at any time.

- -    The Trust also reserves the right to redeem your shares under certain
     circumstances. You will receive written notice at least 60 days prior to
     the redemption of your shares by the Trust.

- -    The Trust may redeem your shares when the aggregate value of your account
     falls below $800 (other than as a result of market action) unless you
     purchase additional shares to increase the value of your account to at
     least $1,000 before the end of the 60-day period.

- -    The Trust will redeem your shares if you do not provide a valid U. S.
     social security number or taxpayer identification number or other requested
     documents before the end of the 60-day period.

- -    Trustees of The Gateway Trust can terminate any series of the Trust upon
     written notification to the shareholders of the applicable series.

- -    The Trust also reserves the right to make a "redemption in kind" - payment
     in portfolio securities rather than cash - if the amount you are redeeming
     is large enough to affect Fund operations.

- -    The right of redemption may be suspended in certain circumstances, such as
     the closing of the New York Stock Exchange for a period other than
     weekends, national holidays, or Good Friday.



                                       13
<PAGE>   15

BACK COVER PAGE OF PROSPECTUS

GATEWAY FUND

More information on the Gateway Fund, including a Statement of Additional
Information (SAI), Annual Report, and Semi-Annual Report, is available without
charge upon request.

The Statement of Additional Information provides more details about the Gateway
Fund and its policies. A current SAI is on file with the Securities and Exchange
Commission (SEC) and is incorporated by reference (i.e. it is legally considered
a part of this prospectus).


The Annual and Semi-Annual Reports include the Gateway Fund's financial
statements, list portfolio holdings, and contain a letter from the Fund's
portfolio manager discussing recent market conditions, economic trends, and Fund
strategies that significantly affected the Fund's performance during the last
fiscal year.


INFORMATION IS AVAILABLE:

By Telephone: (800) 354-6339

By Mail: The Gateway Trust
                          Shareholder Services
                          P. O. Box 5211
                          Cincinnati, OH  45201-5211


By E-mail:        [email protected]

On the Internet:  www.gatewayfund.com

Information about the Fund (including the SAI) can be reviewed and copied by
visiting the SEC's Public Reference Room in Washington, D.C. Information on the
operation of the Public Reference Room may be obtained by calling the SEC at
(202) 942-8090. Reports and other information about the Fund are available on
the EDGAR Database on the SEC's Internet site at http://www.sec.gov or by
sending your request and a duplicating fee to the SEC's Public Reference
Section, Washington, D.C. 20549-0102 or at the following e-mail address:
[email protected].


The Gateway Fund is a series of The Gateway Trust, SEC file number: 811-02773.



                                       14
<PAGE>   16

FRONT COVER


Gateway Small Cap Index Fund


PROSPECTUS May 1, 2000



As with all mutual funds, the Securities and Exchange Commission has not
determined that the information in this prospectus is accurate or complete, nor
has it approved or disapproved the Fund's shares. It is a criminal offense to
state otherwise.


The Gateway Trust




<PAGE>   17

                                TABLE OF CONTENTS
<TABLE>
<CAPTION>


<S>                                                                                        <C>
Gateway Small Cap Index Fund Investment Objective and Principal Strategies...................3
Principal Risks..............................................................................3
Past Performance.............................................................................4
Expenses.....................................................................................5
   Annual Fund Operating Expenses............................................................5
   Management Fees...........................................................................5
   Other Expenses............................................................................5
More Information about Principal Investment Strategies and Risks.............................6
   Principal Investment Strategies...........................................................6
   Risks.....................................................................................6
About the Investment Adviser.................................................................7
   Portfolio Manager Profile.................................................................7
Other Information............................................................................8
   How Fund Shares Are Priced................................................................8
   Dividends and Distributions...............................................................8
   Tax Issues................................................................................8
Financial Highlights.........................................................................9
Investing Through a Financial Professional..................................................10
Investing Directly..........................................................................10
   Opening Your Account.....................................................................10
   Additional Investments...................................................................12
How To Redeem Your Shares...................................................................13
Additional Information About Purchasing and Redeeming Shares................................14
</TABLE>





                                       2
<PAGE>   18


GATEWAY SMALL CAP INDEX FUND INVESTMENT OBJECTIVE AND PRINCIPAL STRATEGIES

The investment objective of the Gateway Small Cap Index Fund is long-term growth
of capital. The Fund invests in the 250 stocks included in the Wilshire Small
Cap Index. At times, the Fund may purchase index put options to reduce the risk
of principal loss or it may buy index call options to increase the potential for
gain. The Wilshire Small Cap Index consists of the common stock of 250 companies
with a median market capitalization of approximately $895 million, selected by
Wilshire Associates to reflect the general characteristics and performance
profile of small companies.


The Adviser monitors the composition of the equity portion of the Fund's
portfolio on a daily basis, and adjusts it as necessary in order to maintain a
correlation of 95% or greater with the Wilshire Small Cap Index. The Fund's
overall portfolio composition may deviate from that of the Wilshire Small Cap
Index to the extent that it may invest up to 5% of its total assets in index
call or index put options, and may also hold cash for purposes of liquidity.
Owing to its ability to hold index put and call options and cash, the Fund's
performance may deviate significantly from that of the Wilshire Small Cap Index.

The Fund is designed for you if you are an aggressive investor whose investment
objective is long-term growth of capital.

PRINCIPAL RISKS
The Fund's stock portfolio is subject to market risk. Stock prices may decline
over short or even extended periods of time. The equity portion of the Fund's
portfolio consists entirely of small capitalization stocks. Investments in
companies with smaller capitalization are generally more volatile and less
liquid than investments in companies with larger capitalization.

When the Fund purchases index put or call options, it risks the loss of the cash
paid for the options. The Fund's use of option strategies may not increase its
returns or fully protect it against declines in the value of its stock
portfolio. Furthermore, the use of option strategies may cause the Fund's
performance to fail to track the results of the underlying Wilshire Small Cap
Index.

The value of your investment in the Fund may go up and down. You could lose
money investing in the Fund. Furthermore, because the Fund has a long-term
investment objective, it is not appropriate for short-term investments.




                                       3
<PAGE>   19


PAST PERFORMANCE

The bar chart and table below show the variability of the Fund's returns, which
is one indicator of the risks of investing in the Fund. As with all mutual
funds, historical results do not necessarily indicate how the Fund will perform
in the future. The bar chart shows the Fund's annual total returns for each of
the last six years and how returns can fluctuate from year to year. All return
figures on this page assume the reinvestment of dividends and distributions.
Also shown are the best and worst quarterly returns for the Fund over the same
time period.


(Insert Bar Chart)

(Plot Points for Bar Chart)
Gateway Small Cap Index Fund
Annual Total Returns as of December 31,
1994            -5.99%
1995            21.81%
1996            17.04%
1997            20.64%
1998            -3.40%
1999            29.13%


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

BEST QUARTER - 4TH QUARTER 1999                            21.34%
WORST QUARTER - 3RD QUARTER 1998                          -21.91%


The following table compares the Fund's performance over time to that of the
Wilshire Small Cap Index and the Russell 2000 Index. The Wilshire Small Cap and
Russell 2000 indexes were chosen for comparison as representative of the small
capitalization sector of the U. S. stock market. The Fund's portfolio is based
on the Wilshire Small Cap Index.
<TABLE>
<CAPTION>


                                                             AVERAGE ANNUAL TOTAL RETURNS
                                                               AS OF DECEMBER 31, 1999
                                              -----------------------------------------------------------
                                                     1 YEAR              5 YEARS        SINCE INCEPTION
                                                                                          ON 6/16/93
                                              ---------------------- ----------------- ------------------
<S>                                                  <C>                  <C>               <C>
Gateway Small Cap Index Fund                         29.13%               16.49%            12.40%
Wilshire Small Cap Index                             37.40%               21.26%            17.47%
Russell 2000 Index                                   21.26%               16.69%            12.73%


</TABLE>



                                       4
<PAGE>   20


EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that are deducted from Fund assets)


Management Fees                             0.90%
Distribution (12b-1) Fees                   N/A
Other Expenses                              1.14
Total Annual Fund Operating Expenses *      2.04%

* Actual expense ratio for 1999 was 1.47%, net of fee waivers of 0.57%. A fee
waiver sufficient to limit the actual expense ratio to 1.50% is expected to
continue at least through 2000.


EXAMPLE
This Example helps you compare the cost of investing in the Fund with the cost
of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods
indicated and then redeem all of your shares at the end of those periods. The
Example also assumes that your investment has a 5% return each year and that the
Fund's operating expenses remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

     1 Year          3 Years        5 Years        10 Years
- ---------------------------------------------------------------
      $207            $640           $1,098         $2,369



MANAGEMENT FEES

The Adviser is paid a fee for managing the Fund's investment portfolio. For the
1999 fiscal year, the Fund paid the Adviser a net fee of 0.33% (after fee
waivers of 0.57%) of its average net assets.


OTHER EXPENSES
The Fund pays all of its normal operating expenses, including: custodial fees,
registration of Fund shares with federal and state securities agencies, and the
Fund's share of general expenses of The Gateway Trust (the "Trust"). Also
included in this category are fees paid to the Adviser for its transfer agency,
fund accounting, and other services to the Fund. The Fund also reimburses the
Adviser for compliance expenses.



                                       5
<PAGE>   21


MORE INFORMATION ABOUT PRINCIPAL INVESTMENT STRATEGIES AND RISKS

PRINCIPAL INVESTMENT STRATEGIES

PURCHASING STOCKS
The Gateway Small Cap Index Fund invests in the 250 stocks included in the
Wilshire Small Cap Index. Each stock is held in approximately the same
proportion as in the Wilshire Small Cap Index. For example, if a stock
represents 1% of the value of the Wilshire Small Cap Index, the Fund invests
approximately 1% of its assets in the stock. The Adviser monitors the
composition of the Wilshire Small Cap Index and makes adjustments to the Fund's
portfolio as needed. The Fund is not affiliated with or sponsored by Wilshire
Associates.

PURCHASING INDEX PUT OPTIONS
The Fund occasionally buys index put options in an attempt to protect the Fund
from a significant market decline in a short period of time. The value of an
index put option generally increases as stock prices decrease. The Fund may not
spend more than 5% of its assets to purchase index put options.

PURCHASING INDEX CALL OPTIONS
The Fund occasionally buys index call options in an attempt to increase the
Fund's participation in short-term upward market movements. The value of an
index call option generally increases as stock prices increase. The Fund may not
spend more than 5% of its assets to purchase index call options.

OTHER INVESTMENTS
Under normal circumstances, the Fund may hold cash for purposes of liquidity.
Cash is normally invested in repurchase agreements. In a repurchase agreement,
the Fund buys securities and the seller agrees at the time of sale to repurchase
the securities at an agreed-upon date, price, and interest rate. The Fund may
not invest more than 5% of its assets in repurchase agreements with a maturity
longer than seven days.

RISKS

PURCHASING STOCKS
Historically, stocks produce greater returns than other investment alternatives;
however returns on stocks also tend to be more volatile. The Fund's option
strategies may not fully protect it against declines in the value of its stock
portfolio. The Fund could experience a loss in both the stock and option
portions of its portfolio.

PURCHASING INDEX OPTIONS
The Fund risks losing all or part of the cash paid for purchasing index options.







                                       6
<PAGE>   22


ABOUT THE INVESTMENT ADVISER

Gateway Investment Advisers, L.P. (the "Adviser") has acted as the investment
adviser for the Gateway Small Cap Index Fund since December 15, 1995. It is
located at 400 TechneCenter Drive, Milford, Ohio 45150. The predecessor to the
Adviser was Gateway Investment Advisers, Inc. which provided the same services
to the Fund prior to December 15, 1995. As of December 31, 1999, the Adviser had
approximately $1.45 billion in assets under management, including approximately
$1 billion in assets invested in all of The Gateway Trust's mutual fund series.
The Adviser provides the Fund with investment research and advice, as well as
administration, accounting, transfer agency, and shareholder services. The fees
paid to the Adviser are shown in the expense table on page 5.

PORTFOLIO MANAGER PROFILE
J. Patrick Rogers, CFA
Portfolio Manager from 1997
Co-Portfolio Manager from 1994
MBA Xavier University 1994
BBA University of Notre Dame 1986
Age 36


J. Patrick Rogers, CFA, joined Gateway Investment Advisers, Inc., general
partner of Gateway Investment Advisers, L.P., in 1989 and has been its president
and a member of its board of directors since 1995. He is the portfolio manager
for the Gateway Small Cap Index Fund as well as the Gateway Fund and the
Cincinnati Fund(R). In addition, he is the president and a trustee of The
Gateway Trust.



                                       7
<PAGE>   23


OTHER INFORMATION

HOW FUND SHARES ARE PRICED
Your price for Fund shares is the Fund's net asset value per share (NAV), which
is ordinarily determined as of the close of the New York Stock Exchange (the
"NYSE"), normally 4:00 P.M. Eastern Time, on each day the NYSE is open. The NYSE
is not open on weekends, national holidays, or Good Friday. Your order will be
priced at the next NAV calculated after your request has been received in good
order as described below.


The Fund normally values stocks at market value and options at the average of
the closing bid and asked quotations. Under normal circumstances, closing option
quotations are considered to reflect the option contract values as of the stock
market close and will be used to value the option contracts. Securities for
which market quotations are not readily available, securities in which trading
has been suspended during the day, and all other assets are valued at fair
value. Furthermore, if the Adviser determines that closing options quotations do
not reflect option contract values as of the close of the NYSE, options are
valued at fair value. Fair value is determined in good faith under procedures
adopted by the Board of Trustees.


DIVIDENDS AND DISTRIBUTIONS
The Fund normally declares dividends and distributions of net capital gains at
the end of December. The capital gains distribution has varied considerably from
year to year. Unless otherwise instructed, dividends and capital gains are
reinvested in the Fund.

TAX ISSUES
The Fund distributes substantially all of its income and realized capital gains
and these distributions may be taxable to you. In addition, gains on any sale of
Fund shares including exchanges into other funds may be taxable to you.


If you buy Fund shares just before a distribution is declared, you will pay the
full price for the shares and then receive a portion of the price back as a
taxable distribution. The distribution paid to you would generally be included
in your gross income for tax purposes, whether or not you reinvested it. For
this reason, you should carefully consider the tax consequences of buying shares
of the Fund in late December.





                                       8
<PAGE>   24

FINANCIAL HIGHLIGHTS
The financial highlights table is intended to help you understand the Fund's
performance for the past five years. Certain information reflects results for a
single Fund share. The total returns in the table represent the rate an investor
would have earned (or lost) on an investment in the Fund, assuming reinvestment
of all dividends and distributions. This information has been audited by Arthur
Andersen LLP whose report, along with the Fund's financial statements, is
included in the Fund's annual report which is available on request.


<TABLE>
<CAPTION>


                                                                      YEAR ENDED DECEMBER 31,
                                                  -----------------------------------------------------------------

                                                      1999          1998          1997        1996      1995 (1)
                                                  -----------------------------------------------------------------
<S>                                               <C>             <C>          <C>          <C>          <C>
Net asset value, beginning of year                $      11.53    $    13.48   $    12.06   $    11.05   $     9.63
                                                  ------------    ----------   ----------   ----------   ----------
Net investment income (loss)                             (0.05)        (0.05)       (0.02)        0.01         0.03

Net gain (loss) on investments                            3.39         (0.41)        2.51         1.87         2.07
                                                  ------------    ----------   ----------   ----------   ----------

  Total from investment operations                        3.34         (0.46)        2.49         1.88         2.10
                                                  ------------    ----------   ----------   ----------   ----------


Dividends from net investment income                        --            --           --        (0.01)       (0.01)
Distributions from net realized gain                     (1.21)        (1.45)       (1.07)       (0.86)       (0.67)
Distributions in excess of net realized gain                --         (0.04)          --           --           --
                                                  ------------    ----------   ----------   ----------   ----------

  Total distributions                                    (1.21)        (1.49)       (1.07)       (0.87)       (0.68)
                                                  ------------    ----------   ----------   ----------   ----------

Net asset value, end of year                      $      13.66    $    11.53   $    13.48   $    12.06   $    11.05
                                                  ============    ==========   ==========   ==========   ==========

TOTAL RETURN                                             29.13%        (3.40%)      20.64%        17.4%       21.81%

Net assets, end of year (thousands)               $     18,047    $   14,128   $   15,811   $   10,921   $    9,418
Ratio of expenses to average net assets                   1.47%(2)      1.50%        1.50%        1.50%        1.68%
Ratio of net investment income (loss)
   to average net assets                                 (0.43%)(2)    (0.42%)      (0.19%)       0.03%        0.09%
Portfolio turnover rate                                     64%           30%          32%          20%          20%
</TABLE>

(1)  On December 15, 1995, Gateway Investment Advisers, L.P. succeeded Gateway
     Investment Advisers, Inc. as investment adviser to the Fund.

(2)  The ratio of expenses to average net assets would have increased and the
     ratio of net investment income to average net assets would have decreased
     by 0.03% in 1999 had the Adviser not voluntarily waived fees. The 1999
     voluntary fee waiver is not expected to recur.





                                       9
<PAGE>   25


INVESTING THROUGH A FINANCIAL PROFESSIONAL

You may purchase or sell Fund shares through a financial professional,
broker/dealer, bank or other financial institution, or an organization that
provides recordkeeping and consulting services to employee benefit plans (a
"Financial Institution"). A Financial Institution may charge you a fee for this
service and may require different minimum initial and subsequent investments
than if you invest in the Fund directly. Financial Institutions may also impose
other charges or restrictions different from those that apply to shareholders
who invest in the Fund directly. A Financial Institution, rather than its
customer, may be the shareholder of record of your shares. The Fund is not
responsible for the failure of any Financial Institution to carry out its
obligations to its customers. Certain Financial Institutions may receive
compensation from The Gateway Trust or its affiliates and they may receive
compensation from the Trust for shareholder recordkeeping and other services.
You should ask about any fees related to your investment in the Fund that are
not described in this Prospectus.



INVESTING DIRECTLY

Customer service representatives are available to assist you Monday through
Friday, from 8:30 A.M. to 5:30 P.M. Eastern Time, toll-free at (800) 354-6339.


OPENING YOUR ACCOUNT
The Gateway Small Cap Index Fund is available for purchase by individuals in
both taxable and IRA accounts, as well as by corporations, trusts, and pension
plans. After your initial purchase and any subsequent transaction, you will
receive a confirmation statement showing the resulting value of your account.

OPENING A REGULAR (NON-IRA) ACCOUNT
To open a regular account in the Fund, please complete and sign a New Account
Application that accompanies this Prospectus. The minimum investment is $1,000.

OPENING AN IRA ACCOUNT
To open an IRA account, please complete and sign an IRA Account Application. The
minimum investment for an IRA is $500. If you have not received an IRA Account
Application and an IRA Agreement and Disclosure Statement, please call customer
service at (800) 354-6339. To transfer an existing IRA to the Gateway Small Cap
Index Fund, you need to complete an IRA Transfer Form in addition to an IRA
Account Application. To transfer or roll over funds from an employer-sponsored
plan such as a 401(k), please call customer service at (800) 354-6339. You will
find more detailed information about transfers to and distributions from IRAs in
the IRA Agreement and Disclosure Statement.

BY MAIL
Please mail your Application (and IRA forms if needed), and a check for your
initial investment, payable to The Gateway Trust, to:
         The Gateway Trust
         Shareholder Services
         P.O. Box 5211
         Cincinnati, OH 45201-5211




                                       10
<PAGE>   26

BY TELEPHONE
To open your account by telephone, you must wire your initial investment to The
Gateway Trust. If you buy shares through a wire transfer, Gateway will not
charge you for the wire. Your financial institution may charge you for this
service. Please call customer service at (800) 354-6339 for further
instructions.




                                       11
<PAGE>   27

ADDITIONAL INVESTMENTS
You may add to your Gateway Small Cap Index Fund investment at any time. The
minimum amount of an additional investment is $100.

BY MAIL
Please mail an Additional Investment Form with your check. Additional Investment
Forms and business reply envelopes are included with most mailings you receive
from the Fund. All checks should be payable to The Gateway Trust.

BY TELEPHONE
To invest by telephone, you will need to wire your investment to the Fund.
Please call customer service at (800) 354-6339 for further information or to
place a purchase order. If money is wired without a purchase order, it will be
returned uninvested.

BY AUTOMATIC INVESTMENT PROGRAM
Our Automatic Investment Program is a convenient way to make regularly scheduled
investments in the Gateway Small Cap Index Fund. When you use the program, funds
are electronically transferred from your bank account to Gateway and additional
shares are then purchased for your account. This service is available on a
monthly or quarterly basis with a minimum of $100 per transfer. Your financial
institution may charge you for transfers from your bank account to a Gateway
fund through the Automatic Investment Program. Please call customer service at
(800) 354-6339 for further instructions.

BY EXCHANGE FROM ANOTHER GATEWAY FUND
You may purchase shares by exchanging from another Gateway mutual fund. Please
call customer service at (800) 354-6339 for further instructions.

The Trust does not charge any fee for exchanges between Gateway funds.
Generally, an exchange between funds is a taxable event. State securities laws
may restrict your ability to make exchanges. The Trust reserves the right to
terminate, upon written notice, the exchange privilege for any shareholder who
makes an excessive number of exchanges between funds. The Trust also reserves
the right to terminate or modify the exchange privilege or to refuse an exchange
if the exchange would adversely affect any Gateway fund involved in the
exchange.




                                       12
<PAGE>   28


HOW TO REDEEM YOUR SHARES
You may redeem your Gateway Small Cap Index Fund shares by choosing one of the
following options. The proceeds will be mailed or wired. Normally the proceeds
will be sent on the next business day. Payments to shareholders who have
purchased shares by check will not be made until the purchase check has cleared,
which could take up to fifteen days from the date of purchase. For information
about redeeming shares from an IRA, please call customer service at (800)
354-6339.

BY MAIL
You may send a written request to redeem shares to:
         The Gateway Trust
         Shareholder Services
         P.O. Box 5211
         Cincinnati, OH 45201-5211
Your written request should specify the number of Fund shares or the dollar
amount to be redeemed. All owners must sign the request exactly as their names
appear on the account. In certain cases, other supporting legal documents may be
required. A check for the proceeds will be mailed to the address of record for
your account.

A signature guarantee is not usually required. However, a signature guarantee
may be required under certain circumstances. A signature guarantee is always
required if proceeds are to be paid to persons other than the record owner(s) of
the shares, or if the proceeds are to be sent to any address other than the
address of record for the account. An acceptable signature guarantee may be
obtained from banks, brokers, and certain other financial institutions. Notary
publics cannot guarantee your signature.

BY TELEPHONE
Unless you have declined telephone exchange and/or redemption privileges, you
may redeem your shares by calling customer service. Telephone redemptions are
not available for IRA accounts. If you redeem your shares by telephone, the
redemption proceeds can only be paid:
- -    by check to the owner(s) of the shares shown on Gateway's records and
     mailed to the address shown on Gateway's records for your account; or
- -    by wire if you completed the wire transfer instructions in your original
     New Account Application or you have sent separate wire transfer
     instructions. All owners must sign the request to establish wire transfer
     instructions exactly as their names appear on the account and the
     signatures must be guaranteed. If you redeem shares through a wire
     transfer, the Trust's custodian will assess a wire charge of $10. Your
     financial institution may also charge you for receiving a wire transfer of
     redemption proceeds.
The Gateway Trust will not be liable for any damages resulting from following
instructions received by telephone that it reasonably believes to be genuine.
The Trust will employ reasonable procedures to confirm that telephone
instructions are genuine.

SYSTEMATIC WITHDRAWAL PROGRAM
If the value of your account is at least $5,000, you can arrange for systematic
quarterly or monthly withdrawals in the amount of $100 or more. Please call
customer service at (800) 354-6339 to make arrangements to use this program.




                                       13
<PAGE>   29


ADDITIONAL INFORMATION ABOUT PURCHASING AND REDEEMING SHARES

- - The Gateway Trust reserves the right to reject any investment at any time.
- - The Trust also reserves the right to redeem your shares under certain
  circumstances. You will receive written notice at least 60 days prior to
  the redemption of your shares by the Trust.
- - The Trust may redeem your shares when the aggregate value of your
  account falls below $800 (other than as a result of market action)
  unless you purchase additional shares to increase the value of your
  account to at least $1,000 before the end of the 60-day period.
- - The Trust will redeem your shares if you do not provide a valid U. S.
  social security number or taxpayer identification number or other
  requested documents before the end of the 60-day period.
- - Trustees of The Gateway Trust can terminate any series of the Trust
  upon written notification to the shareholders of the applicable series.
- - The Trust also reserves the right to make a "redemption in kind" - payment
  in portfolio securities rather than cash - if the amount you are redeeming
  is large enough to affect Fund operations.
- - The right of redemption may be suspended in certain circumstances, such as
  the closing of the New York Stock Exchange for a period other than
  weekends, national holidays, or Good Friday.



                                       14
<PAGE>   30


BACK COVER PAGE OF PROSPECTUS

GATEWAY SMALL CAP INDEX FUND

More information on the Gateway Small Cap Index Fund, including a Statement of
Additional Information (SAI), Annual Report, and Semi-Annual Report, is
available without charge upon request.

The Statement of Additional Information provides more details about the Gateway
Small Cap Index Fund and its policies. A current SAI is on file with the
Securities and Exchange Commission (SEC) and is incorporated by reference (i.e.
it is legally considered a part of this prospectus).


The Annual and Semi-Annual Reports include the Gateway Small Cap Index Fund's
financial statements, list portfolio holdings, and contain a letter from the
Fund's portfolio manager discussing recent market conditions, economic trends,
and Fund strategies that significantly affected the Fund's performance during
the last fiscal year.


INFORMATION IS AVAILABLE:

By Telephone: (800) 354-6339

By Mail: The Gateway Trust
                          Shareholder Services
                          P. O. Box 5211
                          Cincinnati, OH  45201-5211


By E-mail:  [email protected]


Information about the Fund (including the SAI) can be reviewed and copied by
visiting the SEC's Public Reference Room in Washington, D.C. Information on the
operation of the Public Reference Room may be obtained by calling the SEC at
(202) 942-8090. Reports and other information about the Fund are available on
the EDGAR Database on the SEC's Internet site at http//www.sec.gov or by sending
your request and a duplicating fee to the SEC's Public Reference Section,
Washington, D.C. 20549-0102 or at the following e-mail address:
[email protected].


The Gateway Small Cap Index Fund is a series of The Gateway Trust, SEC file
number: 811-02773.



                                       15
<PAGE>   31

[The Prospectus dated May 1, 1999 for the Cincinnati Fund is incorporated
herein by reference to Registrant's Post-Effective Amendment No. 34 (Investment
Company Act No. 32) to Registration Statement No. 2-59895 with the Securities
and Exchange Commission on April 30, 1999.]




                               CINCINNATI FUND(R)


                          SUPPLEMENT DATED MAY 1, 2000
                                       TO
                          PROSPECTUS DATED MAY 1, 1999

===============================================================================


The following material supplements the Prospectus dated May 1, 1999, for the
Cincinnati Fund(R) (the "Fund"), and particularly all information contained
under "Past Performance" on page 4 of the Prospectus, "Expenses" on page 5 of
the Prospectus, "Financial Highlights" on page 10 of the Prospectus, and the
second paragraph under How Fund Shares Are Priced under "Other Information" on
page 9 of the Prospectus. The Fund is a series of The Gateway Trust.


Performance and expense information for the Fund is updated as follows:

PAST PERFORMANCE

The bar chart and table below show the variability of the Fund's returns, which
is one indicator of the risks of investing in the Fund. As with all mutual
funds, historical results do not necessarily indicate how the Fund will perform
in the future. The bar chart shows the Fund's annual total returns for each of
the last five years and how returns can fluctuate from year to year. All return
figures on this page assume the reinvestment of dividends and distributions.
Also shown are the best and worst quarterly returns for the Fund over the same
time period.

(Insert Bar Chart)
(Plot Points for Bar Chart)
Cincinnati Fund(R)
Annual Total Returns as of December 31,
1995            35.31%
1996            19.98%
1997            28.98%
1998            11.89%
1999            -4.13%

- --------------------------------------------------------------------------------
BEST QUARTER                 FOURTH QUARTER 1998                    19.92%
WORST QUARTER                THIRD QUARTER 1998                    -13.86%


The following table compares the Fund's performance over time to that of the S&P
500 Index and the Russell 2000 Index. The S&P 500 and Russell 2000 indexes are
popular indicators of the performance of the large and small capitalization
sectors, respectively, of the U. S. stock market. These indexes were chosen for
comparison because they reflect the broad spectrum of U. S. equity markets.



<PAGE>   32



<TABLE>
<CAPTION>

                                                   AVERAGE ANNUAL TOTAL RETURNS
                                                     AS OF DECEMBER 31, 1999
                                       1 YEAR                5 YEAR           SINCE INCEPTION ON
                                                                                   11/7/94
                                --------------------- --------------------- -----------------------
<S>                                    <C>                   <C>                    <C>
Cincinnati Fund(R)                    -4.13%                 17.57%                 16.81%
S&P 500 Index                         21.01%                 28.49%                 27.53%
Russell 2000 Index                    21.26%                 16.69%                 13.79%
</TABLE>





EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Fund.

ANNUAL FUND OPERATING EXPENSES
(expenses that are deducted from Fund assets)

Management Fees                             0.50%
Distribution (12b-1) Fees                   N/A
Other Expenses                              0.78%
                                            -----
Total Annual Fund Operating Expenses        1.28%
                                            =====

EXAMPLE
This Example helps you compare the cost of investing in the Fund with the cost
of investing in other mutual funds.

The Example assumes that you invest $10,000 in the Fund for the time periods
indicated and then redeem all of your shares at the end of those periods. The
Example also assumes that your investment has a 5% return each year and that the
Fund's operating expenses remain the same. Although your actual costs may be
higher or lower, based on these assumptions your costs would be:

     1 Year          3 Years        5 Years        10 Years
- ---------------------------------------------------------------
      $130            $406            $702          $1,545

MANAGEMENT FEES
The Adviser is paid a fee for managing the Fund's investment portfolio. For the
1999 fiscal year, the Fund paid the Adviser a fee of 0.50% of its average net
assets.


OTHER EXPENSES
The Fund pays all of its normal operating expenses, including: custodial fees,
registration of Fund shares with federal and state securities agencies, and the
Fund's share of general expenses



<PAGE>   33


of The Gateway Trust (the "Trust"). Also included in this category are fees paid
to the Adviser for its transfer agency, fund accounting, and other services to
the Fund. The Fund also reimburses the Adviser for compliance expenses.


OTHER INFORMATION

HOW FUND SHARES ARE PRICED

Effective May 1, 2000, the Fund normally values stocks at market value instead
of the average of the closing bid and asked quotations. All other pricing
policies are unchanged.



<PAGE>   34






FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the Fund's
performance for the past five years. Certain information reflects results for a
single Fund share. The total returns in the table represent the rate an investor
would have earned (or lost) on an investment in the Fund, assuming reinvestment
of all dividends and distributions. This information has been audited by Arthur
Andersen LLP whose report, along with the Fund's financial statements, is
included in the Fund's annual report, which is available on request. Updated
performance information as well as a change in the Fund's pricing policy is
outlined in this supplement as well.








<TABLE>
<CAPTION>
                                                             Year Ended December 31,
                                           1999         1998          1997          1996         1995 (1)
                                           ----         ----          ----          ----         --------

<S>                                       <C>          <C>            <C>          <C>          <C>
Net asset value, beginning of year         $20.84       $18.98         $15.40       $13.12       $   9.91
                                          -------      -------        -------      -------       --------

Net investment income                        0.12         0.06           0.07         0.02           0.04
Net gain (loss) on investments              (0.98)        2.20           4.39         2.60           3.46
                                         --------     ---------      ---------    ---------      --------

   Total from investment operations         (0.86)        2.26           4.46         2.62           3.50
                                         --------     ---------      ---------    ---------      --------

Dividends from net investment income        (0.12)       (0.06)         (0.07)       (0.02)         (0.07)
Distributions from net realized gain        (0.02)       (0.34)         (0.81)       (0.32)         (0.22)
                                         --------     --------       --------     --------       --------

   Total distributions                      (0.14)       (0.40)         (0.88)       (0.34)         (0.29)
                                         --------     --------       --------     --------       --------

Net asset value, end of year               $19.84       $20.84         $18.98       $15.40         $13.12
                                           =======      =======        =======      =======        ======

TOTAL RETURN                                (4.13%)      11.89%         28.98%       19.98%         35.31%

Net assets, end of year (millions)        $19,880      $26,544        $17,527       $8,984         $5,877

Ratio of expenses to average net             1.28%        1.37%          1.69%        2.00%          1.98%
assets (2)

Ratio of net investment income
   to average net assets (2)                 0.49%        0.30%          0.50%        0.13%          0.46%

Portfolio turnover rate                        22%           8%            17%          10%             9%
</TABLE>


(1)  On December 15, 1995, Gateway Investment Advisers, L.P. succeeded Gateway
     Investment Advisers, Inc. as


<PAGE>   35

     investment adviser to the Fund.

(2)  The ratio of expenses to average net assets would have increased and the
     ratio of net investment income to average net assets would have decreased
     by 0.01% in 1997 and 0.02% in 1995 had the Adviser not voluntarily waived
     fees or reimbursed expenses.









Information about the Fund (including the SAI) can be reviewed and copied by
visiting the SEC's Public Reference Room in Washington, D.C. Information on the
operation of the Public Reference Room may be obtained by calling the SEC at
(202) 942-8090. Reports and other information about the Fund are available on
the EDGAR Database on the SEC's Internet site at http//www.sec.gov or by sending
your request and a duplicating fee to the SEC's Public Reference Section,
Washington, D.C. 20549-0102 or at the following e-mail address:
[email protected].


<PAGE>   36

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

                                THE GATEWAY TRUST

                                  Gateway Fund
                                       and
                          Gateway Small Cap Index Fund

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




                       STATEMENT OF ADDITIONAL INFORMATION
                                DATED MAY 1, 2000




         This Statement is not a prospectus but should be read in conjunction
with the current prospectuses of The Gateway Trust for the Gateway Fund and the
Gateway Small Cap Index Fund dated May 1, 2000, and any supplement thereto. A
copy of these prospectuses may be obtained from the Trust by written or
telephone request directed to the Trust at the address or the telephone number
shown below.

         The financial statements and independent auditors' report required to
be included in this SAI are incorporated herein by this reference to the annual
and semi-annual reports of the Funds for the fiscal year ended December 31,
1999, and year-to-date ended June 30, 1999, respectively.

         The prospectuses of the Gateway Fund and the Gateway Small Cap Index
Fund dated May 1, 2000, are also incorporated herein by reference.






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

                                 P. O. BOX 5211
                           CINCINNATI, OHIO 45201-5211
                                 (800) 354-6339

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


<PAGE>   37


                                TABLE OF CONTENTS
                                -----------------

<TABLE>


<S>                                                                                                         <C>
INTRODUCTION.................................................................................................3
     General Information About The Gateway Trust.............................................................3
INVESTMENT OBJECTIVES AND PRACTICES..........................................................................3
     Gateway Fund............................................................................................3
     Gateway Small Cap Index Fund............................................................................4
OPTION TRANSACTIONS..........................................................................................4
     Selling Covered Call Options............................................................................4
     Selling Covered Put Options.............................................................................5
     Purchase Of Put And Call Options........................................................................5
     Options On Securities Indexes...........................................................................5
     Covered Index Call Options Sold By The Gateway Fund.....................................................6
INVESTMENT PRACTICES, RISKS, AND RESTRICTIONS................................................................6
     Other Investment Practices..............................................................................6
     Certain Risks...........................................................................................7
     Investment Restrictions.................................................................................7
PERFORMANCE AND RISK INFORMATION............................................................................10
     Performance Information................................................................................10
         Total Return Calculations..........................................................................11
         Historical Results.................................................................................11
     Risk Information.......................................................................................12
         Comparative Indexes................................................................................12
         Standard Deviation.................................................................................12
         Beta...............................................................................................14
     Rankings And Comparative Performance Information.......................................................14
     Portfolio Holdings.....................................................................................14
SHAREHOLDER SERVICES........................................................................................14
     Open Account...........................................................................................14
     Automatic Investment Program...........................................................................15
     IRAs...................................................................................................15
     Systematic Withdrawal Program..........................................................................16
ADDITIONAL PURCHASE AND REDEMPTION INFORMATION..............................................................16
INVESTMENT ADVISORY AND OTHER SERVICES......................................................................17
     Gateway Investment Advisers, L.P.......................................................................17
     Gateway Fund Management Agreement......................................................................18
     Gateway Small Cap Index Fund Investment Advisory Contract..............................................19
     Distribution Plan For The Gateway Fund.................................................................21
     Custodian..............................................................................................21
     Shareholder Servicing, Transfer, Dividend Disbursing, And Financial Servicing Agent....................21
BROKERAGE...................................................................................................22
</TABLE>





                                       1
<PAGE>   38


<TABLE>

<S>                                                                                                        <C>
CODE OF ETHICS..............................................................................................24
ADDITIONAL TAX MATTERS......................................................................................24
     Federal Tax Matters....................................................................................24
     State And Local Tax Aspects............................................................................25
TRUSTEES AND OFFICERS OF THE TRUST..........................................................................25
     Shareholder Meetings And Voting........................................................................27
INDEPENDENT PUBLIC ACCOUNTANTS AND FINANCIAL STATEMENTS.....................................................27
PRINCIPAL HOLDERS OF FUND SHARES............................................................................27
     Gateway Fund...........................................................................................27
     Small Cap Index Fund...................................................................................28
     Shares Held By Adviser.................................................................................29
</TABLE>




                                       2
<PAGE>   39


                                  INTRODUCTION
                                  ------------

GENERAL INFORMATION ABOUT THE GATEWAY TRUST

         The Gateway Trust (the "Trust") is an Ohio business trust which is
authorized to establish and operate one or more separate series of mutual funds
(herein referred to as "Funds" or individually as a "Fund"). Each Fund has its
own investment policies, restrictions, practices, assets, and liabilities. Each
Fund is represented by a separate series of shares of beneficial interest in the
Trust ("Shares"). The Trust's operation is governed by Chapter 1746 of the Ohio
Revised Code, by the Second Amended Agreement and Declaration of Trust dated as
of December 29, 1992, as amended, and by the Trust's bylaws, as amended.

         At present, there are three series of the Trust:

- -------------------------------------------------------------
      NAME OF FUND                     DATE ORGANIZED
- -------------------------------------------------------------

Gateway Fund                           1977

Gateway Small Cap Index Fund           April 1993

Cincinnati Fund                        November 1994
- ------------------------------------ ------------------------

         The Gateway Fund was known as the Gateway Index Plus Fund until April
30, 1998; as Gateway Option Index Fund until March 1990; as Gateway Option
Income Fund until February 1988; and as Gateway Option Income Fund, Inc. until
May 1986. Gateway Option Income Fund, Inc., the predecessor to the Trust, was
organized in 1977 as a Maryland corporation. It was reorganized to become the
Trust effective as of May 2, 1986, with the Gateway Option Income Fund as its
sole initial fund. As a result of the transaction, shareholders of the
corporation on May 2, 1986, became shareholders of the Option Income Fund.

         The Gateway Fund and the Gateway Small Cap Index Fund are offered in
two separate prospectuses. The Cincinnati Fund(R) is offered in a separate
prospectus and has a separate Statement of Additional Information. Gateway
Investment Advisers, L.P. (the "Adviser") acts as the Funds' investment adviser.

                       INVESTMENT OBJECTIVES AND PRACTICES
                       -----------------------------------

GATEWAY FUND

         The investment objective of the Gateway Fund is to capture the majority
of the higher returns associated with equity market investments, while exposing
investors to significantly less risk than other equity investments. Descriptions
of the Fund's current investment practices and strategies and certain risk
factors applicable to the Fund are set forth under the caption "INVESTMENT
OBJECTIVE AND PRINCIPAL STRATEGIES" in the Fund's prospectus.


         The Gateway Fund invests in a portfolio of common stocks which
parallels the composition of the Standard & Poor's 500 Stock Index (the "500
Index"). The Fund sells index call options on the S&P 100 Index, the S&P 500
Index and other stock indexes, and, when appropriate, the Fund enters into
closing purchase transactions with respect to such options. The Fund also
purchases put options on securities indexes.





                                       3
<PAGE>   40

         In addition, the Fund has authority to, and when deemed appropriate
may, invest in the stocks of other securities indexes, sell put options on
securities indexes, and purchase call options on securities indexes; however,
the Fund does not intend to enter into these types of transactions in the coming
year.

         The Gateway Fund is a diversified, open-end management investment
company.

GATEWAY SMALL CAP INDEX FUND

         The investment objective of the Small Cap Index Fund is to achieve
long-term growth of capital. Descriptions of the Fund's current investment
practices and strategies and certain risk factors applicable to the Fund are set
forth under the caption "INVESTMENT OBJECTIVE AND PRINCIPAL STATEGIES" in the
Fund's prospectus.

         The Small Cap Index Fund primarily invests in a portfolio of common
stocks which parallels the composition of the Wilshire Small Cap Index (the "250
Index"). Because the 250 Index is comprised of 250 equity securities and the
Fund purchases such securities in round lots, the portfolio does not correlate
perfectly with the 250 Index. The Adviser monitors the composition of the equity
portion of the Fund's portfolio on a daily basis, and adjusts it as necessary in
order to maintain a correlation of 95% or greater with the 250 Index. The Fund's
overall portfolio composition may deviate from that of the 250 Index to the
extent that it can invest up to 5% of its total assets in index call or index
put options, and may also hold cash primarily for purposes of liquidity. Owing
to its ability to hold index put and call options and cash, the Fund's
performance may deviate significantly from that of the 250 Index. The median
market capitalization of the 250 companies is approximately $658 million.

         The Small Cap Index Fund may also purchase put and call options on
securities indexes such as the S&P 500 Index, the 250 Index, the Russell 2000
Index, and comparable small capitalization securities indexes. The Small Cap
Index Fund limits its aggregate investment in premiums on put and call options
to an amount not exceeding 5% of the Fund's net assets. Options on the 250 Index
are a relatively new investment vehicle and the secondary market for any
particular option on this index at a specific time may be limited.

         The Small Cap Index Fund is a diversified, open-end management
investment company.

                               OPTION TRANSACTIONS
                               -------------------

         This section contains a brief general description of various types of
options, certain option trading strategies, and some of the risks of option
trading. It is included to help a shareholder understand the investment
practices of the Funds. It is easier to understand index options if you
understand options on individual stocks. For this reason, the first three parts
of this section discuss individual stock options.

SELLING COVERED CALL OPTIONS

         A covered call option is an option sold on a security owned by the
seller of the option. If the option is exercised by the purchaser during the
option period, the seller is required to deliver the underlying security against
payment of the exercise price. The seller's obligation terminates upon
expiration of the option period or when the seller executes a closing purchase
transaction with respect to such option.

         The seller of a covered call option gives up, in return for the
premium, the opportunity to profit from an increase in the value of the
underlying security above the exercise price. At the same time, the seller
retains the risk of loss from a decline in the value of the underlying security
during the option period. Although the seller may terminate its obligation by
executing a closing purchase transaction, the cost of effecting such a
transaction may be greater than the premium received upon its sale, resulting in
a loss to the seller. If such an option expires unexercised, the seller realizes
a gain equal to the premium received. Such a gain may be offset or exceeded by a
decline in the market value of the underlying security during the option period.
If an option is exercised, the exercise price, the premium received, and the
market value of the underlying security determine the gain or loss realized by
the seller.



                                       4
<PAGE>   41


         The Gateway Fund is the only Trust fund authorized to sell covered call
options. A more complete description of the details and risks involved in
selling covered call options is set forth below under the caption "COVERED INDEX
CALL OPTIONS SOLD BY THE GATEWAY FUND."

SELLING COVERED PUT OPTIONS

         The seller of a covered put option has the obligation to buy, and the
purchaser the right to sell, the underlying security at the exercise price
during the option period. To cover a put option, a seller usually deposits U. S.
government securities (or other high-grade debt obligations) in a segregated
account at the seller's custodian. The value of the deposited securities is
equal to or greater than the exercise price of the underlying security. The
value of the deposited securities is marked to market daily and, if necessary,
additional assets are placed in the segregated account to maintain a value equal
to or greater than the exercise price. The seller maintains the segregated
account so long as it is obligated as the seller. The obligation of the seller
is terminated when the purchaser exercises the put option, when the option
expires, or when a closing purchase transaction is effected by the seller.

         The seller's gain on the sale of a put option is limited to the premium
received plus interest earned on its segregated account. The seller's potential
loss on a put option is determined by taking into consideration the exercise
price of the option, the market price of the underlying security when the put is
exercised, the premium received, and the interest earned on its segregated
account. Although a seller risks a substantial loss if the price of the stock on
which it has sold a put option drops suddenly, the seller can protect itself
against serious loss by entering into a closing purchase transaction. The degree
of loss will depend upon the seller's ability to detect the movement in the
stock's price and to execute a closing transaction at the appropriate time.

         The Gateway Fund is the only Trust fund authorized to sell covered put
options. To comply with state securities requirements, the Fund will not sell
any covered put option if, as a result, the Fund would have to invest more than
50% of its total assets (taken at current value) to meet its obligation upon the
exercise of put options.

PURCHASE OF PUT AND CALL OPTIONS

         Put options can be employed to protect against declines in the market
value of portfolio securities or to attempt to retain unrealized gains in the
value of portfolio securities. Put options might also be purchased to facilitate
the sale of portfolio securities. Call options can be purchased as a temporary
substitute for the purchase of individual stocks, which then could be purchased
in orderly fashion. Upon the purchase of the stocks, the purchaser would
normally terminate the call position.

         The purchase of both put and call options involves the risk of loss of
all or part of the premium paid. If the price of the underlying stock does not
rise (in the case of a call) or drop (in the case of a put) by an amount at
least equal to the premium paid for the option contract, the purchaser will
experience a loss on the option contract equal to the deficiency.

OPTIONS ON SECURITIES INDEXES

         The Gateway Fund and the Small Cap Index Fund each are authorized to
purchase index put and call options. Each fund limits its aggregate investment
in premiums on put and call options to an amount not exceeding 5% of its net
assets. An option on a securities index is generally similar to an option on an
individual stock, but an option on a securities index is settled only in cash.
The exercising holder of an index option, instead of receiving a security,
receives the difference between the closing price of the securities index and
the exercise price of the index option times a specified multiple ($100 in the
case of the S&P 100 Stock Index). The seller of index options may realize a gain
or loss according to movement in the level of securities prices in that index
and in the securities markets generally.



                                       5
<PAGE>   42

COVERED INDEX CALL OPTIONS SOLD BY THE GATEWAY FUND

         The Gateway Fund sells index call options. Frequently the Fund executes
a closing purchase transaction with respect to the option it has sold and sells
another option (with either a different exercise price or expiration date or
both). The Fund's objective in entering into such closing transactions is to
increase option premium income, to limit losses, or to protect anticipated gains
in underlying stocks. The cost of a closing transaction, while reducing the
premium income realized from the sale of the option, should be offset, at least
in part, by appreciation in the value of the underlying index, and by the
opportunity to realize additional premium income from selling a new option.

         When the Fund sells an index call option, it does not deliver the
underlying stocks or cash to the broker through whom the transaction is
effected. In the case of an exchange-traded option, the Fund establishes an
escrow account. The Trust's Custodian (or a securities depository acting for the
Custodian) acts as the Trust's escrow agent. The escrow agent enters into
documents known as escrow receipts with respect to the stocks included in the
Fund (or escrow receipts with respect to other acceptable securities). The
escrow agent releases the stocks from the escrow account when the call option
expires or the Fund enters into a closing purchase transaction. Until such
release, the underlying stocks cannot be sold by the Fund. The Fund may enter
into similar collateral arrangements with the counterparty when it sells
over-the-counter index call options.

         When the Fund sells an index call option, it is also required to
"cover" the option pursuant to requirements enunciated by the staff of the
Securities and Exchange Commission ("the SEC"). The staff has indicated that a
mutual fund may "cover" an index call option by (1) owning and holding for the
term of the option a portfolio of stocks substantially replicating the movement
of the index underlying the call option; (2) purchasing an American-style call
option on the same index with an exercise price no greater than the exercise
price of the written option; or (3) establishing and maintaining for the term of
the option a segregated account consisting of cash, U. S. government securities,
or other high-grade debt securities, equal in value to the aggregate contract
price of the call option (the current index value times the specific multiple).
The Fund generally "covers" the index options it has sold by owning and holding
stocks substantially replicating the movement of the applicable index. As an
alternative method of "covering" the option, the Fund may purchase an
appropriate offsetting option.

         The purchaser of an index call option sold by the Fund may exercise the
option at a price fixed as of the closing level of the index on the date of
exercise. Unless the Fund has liquid assets sufficient to satisfy the exercise
of the index call option, the Fund would be required to liquidate portfolio
securities to satisfy the exercise. The market value of such securities may
decline between the time the option is exercised and the time the Fund is able
to sell the securities. If the Fund fails to anticipate an exercise, it may have
to borrow from a bank (in amounts not exceeding 5% of the Fund's total assets)
pending settlement of the sale of the portfolio securities and thereby incur
interest charges. If trading is interrupted on the index, the Fund would not be
able to close out its option positions.

                  INVESTMENT PRACTICES, RISKS, AND RESTRICTIONS
                  ---------------------------------------------

OTHER INVESTMENT PRACTICES

         Each fund may hold cash for purposes of liquidity. Each fund generally
will hold cash reserves for the purpose of paying expenses and share redemptions
and may hold cash received from the sale of its shares which has not yet been
invested.

         With respect to the Gateway Fund only, the Adviser may determine from
time to time that, for temporary defensive purposes, the Fund should reduce (and
in periods of unusual market conditions reduce substantially or liquidate
entirely) its investment in common stock. For temporary defensive purposes, the
Gateway Fund may hold up to 100% of its assets in cash.

         Cash is normally invested in repurchase agreements. Cash may also be
invested in securities of the U. S. government or any of its agencies, bankers'
acceptances, commercial paper, or certificates of deposit (collectively "cash
instruments"). Commercial paper investments will be limited to investment grade
issues rated A-1 or A-2 by Standard & Poor's or Prime-1 or Prime-2 by Moody's
Investors Service, Inc. Certificates of deposit investments will be limited to
obligations of domestic banks with assets of $1 billion or more.

         Repurchase agreements are instruments under which a fund buys
securities suitable for investment under its



                                       6
<PAGE>   43

policies and obtains the concurrent agreement of the seller (usually a bank) to
repurchase such securities at an agreed-upon date, price, and interest rate.
Investments in repurchase agreements are subject to the risk that the selling
bank may default in its repurchase obligation. However, not more than 5% of any
fund's total assets may be invested in repurchase agreements which have a
maturity longer than seven days.

CERTAIN RISKS

         The success of each fund's option strategy depends upon the ability of
the Adviser to identify an appropriate index in which to invest and the
Adviser's ability to enter into transactions involving index options at
appropriate times in the stock market cycle. In pursuing this course, the
Adviser is subject to the risks of change in general economic conditions,
adverse developments in specific industries, and factors affecting the
performance of individual stocks.


         The Gateway Fund is not sponsored, endorsed, sold or promoted by
Standard & Poor's, a division of The McGraw-Hill Companies, Inc. ("S&P"). S&P
makes no representation or warranty, express or implied, to the shareholders of
the Fund or any member of the public regarding the advisability of investing in
securities generally or in the Fund particularly or the ability of the S&P 500
Index to track general stock market performance. S&P's only relationship to the
Gateway Trust is the licensing of certain trademarks and trade names of S&P and
of the S&P 500 Index which is determined, composed and calculated by S&P without
regard to the Trust or the Fund. S&P has no obligation to take the needs of the
Fund or its shareholders into consideration in determining, composing or
calculating the S&P 500 Index. S&P is not responsible for and has not
participated in the determination of the prices and amount of the Fund or the
timing of the issuance or sale of the Fund or in the determination or
calculation of the equation by which the Fund is to be converted into cash. S&P
has no obligation or liability in connection with the administration, marketing
or trading of the Fund.

         S&P DOES NOT GUARANTEE THE ACCURACY AND/OR THE COMPLETEMESS OF THE S&P
500 INDEX OR ANY DATA INCLUDED THEREIN AND S&P SHALL HAVE NO LIABILITY FOR ANY
ERRORS, OMISSIONS, OR INTERRUPTIONS THEREIN. S&P MAKES NO WARRANTY, EXPRESS OR
IMPLIED, AS TO RESULTS TO BE OBTAINED BY THE GATEWAY TRUST, SHAREHOLDERS OF THE
FUND, OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE S&P 500 INDEX OR ANY
DATA INCLUDED THERIN. S&P MAKES NO EXPRESS OR IMPLIED WARRANTIES, AND EXPRESSLY
DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
OR USE WITH RESPECT TO THE S&P 500 INDEX OR ANY DATA INCLUDED THERIN. WITHOUT
LIMITING ANY OF THE FOREGOING, IN NO EVENT SHALL S&P HAVE ANY LIABILITY FOR ANY
SPECIAL, PUNITIVE, INDIRECT, OR CONSEQUENTIAL DAMAGES (INCLUDING LOST PROFITS),
EVEN IF NOTIFIED OF THE POSSIBILITY OF SUCH DAMAGES.


         Wilshire Associates, Inc. ("Wilshire") obtains information for
inclusion in or for use in the calculation of the Wilshire Small Cap Index from
sources which Wilshire considers reliable. WILSHIRE HAS ADVISED THE TRUST THAT
IT MAKES NO WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY THE
TRUST OR OWNERS OF THE SMALL CAP INDEX FUND, OR ANY OTHER PERSON OR ENTITY FROM
THE USE OF THE WILSHIRE SMALL CAP INDEX OR ANY DATA INCLUDED THEREIN. WILSHIRE
MAKES NO EXPRESS OR IMPLIED WARRANTIES, AND HEREBY EXPRESSLY DISCLAIMS ALL SUCH
WARRANTIES, OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, FOR USE WITH
RESPECT TO THE WILSHIRE SMALL CAP INDEX OR ANY DATA INCLUDED THEREIN.

INVESTMENT RESTRICTIONS

         The investment objectives and investment restrictions applicable to
each fund are designated as fundamental policies of the fund. The Trust has
adopted other fundamental policies with respect to each of the funds.
Fundamental policies may not be changed without vote of shareholders of that
fund. Under these policies, the Gateway Fund and the Small Cap Index Fund each
are subject to the following restrictions:




                                       7
<PAGE>   44

         1.     A fund may not purchase any security if, as a result, the fund
                (or the funds in the Trust together) would then hold more than
                10% of any class of securities of an issuer (taking all common
                stock issues of an issuer as a single class, all preferred stock
                issues as a single class, and all debt issues as a single
                class), or more than 10% of the outstanding voting securities of
                an issuer.

         2.     A fund may not purchase any security if, as a result, the fund
                would then have more than 5% of its total assets (taken at
                current value) invested in securities of companies (including
                predecessors) less than three years old and in equity securities
                for which market quotations are not readily available.

         3.     A fund may not purchase securities on margin (but a fund may
                obtain such short-term credits as may be necessary for the
                clearance of purchase and sales of securities).

         4.     A fund may not make short sales of securities or maintain a
                short position (a) unless, at all times when a short position is
                open, the fund owns an equal amount of such securities or
                securities convertible into or exchangeable (without payment of
                any further consideration) for securities of the same issue as,
                and equal in amount to, the securities sold short, and (b)
                unless not more than 10% of such fund's net assets (taken at
                current value) are held as collateral for such sales at any one
                time.

                It is the present intention of management to make such sales
                only for the purpose of deferring realization of gain or loss
                for federal income tax purposes. It is the present intention of
                management that short sales of securities subject to outstanding
                options will not be made.

         5.     A fund may not borrow money except as a temporary measure for
                extraordinary or emergency purposes and then only from banks and
                only in amounts not in excess of 5% of the fund's total assets
                (except to meet redemption requests as discussed below), taken
                at the lower of cost or market.

                In order to meet redemption requests without immediately selling
                any portfolio securities, a fund may borrow an amount up to 25%
                of the value of its total assets including the amount borrowed.
                If, due to market fluctuations or other reasons, the value of
                such fund's assets falls below 400% of its borrowing, the fund
                will reduce its borrowing which may result in the fund being
                required to sell securities at a time when it may otherwise be
                disadvantageous to do so. This borrowing is not for investment
                leverage but solely to facilitate management of the portfolio by
                enabling the fund to meet redemption requests where the
                liquidation of portfolio securities is deemed to be inconvenient
                or disadvantageous. However, the fund might be deemed to be
                engaged in leveraging in that any such borrowing will enable the
                fund to continue to earn money on investments which otherwise
                may have been sold in order to meet redemption requests.

         6.     A fund may not pledge more than 10% of its total assets, taken
                at market value. The deposit in escrow of underlying securities
                in connection with the writing of call options is not deemed to
                be a pledge.

         7.     A fund may not purchase or retain securities of any company if,
                to the knowledge of the Trust, officers and trustees of the
                Trust or of the Adviser who individually own more than 1/2 of 1%
                of the securities of that company together own beneficially more
                than 5% of such securities.

         8.     A fund may not buy or sell commodities or commodities futures or
                options contracts, or real estate or interests in real estate,
                although it may purchase and sell (a) securities which are
                secured by real estate, and (b) securities of companies which
                invest or deal in real estate.

         9.     A fund may not act as underwriter except to the extent that, in
                connection with the disposition of portfolio securities, it may
                be deemed to be an underwriter under certain



                                       8
<PAGE>   45

                provisions of the federal securities laws.

         10.    A fund may not make investments for the purpose of exercising
                control or management.

         11.    A fund may not participate on a joint or joint and several basis
                in any trading account in securities.

         12.    A fund may not purchase any security restricted as to
                disposition under the federal securities laws.

         13.    A fund may not invest in securities of other investment
                companies, except as part of a merger, consolidation, or other
                acquisition.

         14.    A fund may not invest in interests in oil, gas, or other mineral
                exploration or development programs, although it may invest in
                the common stocks of companies which invest in or sponsor such
                programs.



                                       9
<PAGE>   46


         15.    A fund may not make loans, except through the purchase of bonds,
                debentures, commercial paper, corporate notes, and similar
                evidences of indebtedness of a type commonly sold privately to
                financial institutions (subject to the limitation in paragraph
                12 above), and except through repurchase agreements.

                No more than 5% of any fund's assets will be invested in
                repurchase agreements which have a maturity longer than seven
                days. In addition, the fund will not enter into repurchase
                agreements with a securities dealer if such transactions
                constitute the purchase of an interest in such dealer under the
                Investment Company Act of 1940. The purchase of a portion of an
                issue of such securities distributed publicly, whether or not
                such purchase is made on the original issuance, is not
                considered the making of a loan.

         16.    A fund may not purchase any security (other than U. S.
                government obligations) if, as a result thereof, less than 75%
                of the value of the fund's total assets is represented by cash
                and cash items (including receivables), government securities,
                and other securities which, for purposes of this calculation,
                are limited in respect of any one issuer to an amount not
                greater in value than 5% of the value of the fund's total assets
                and to not more than 10% of the outstanding voting securities of
                such issuer. All of the funds in the Trust taken as a group also
                must satisfy this 10% test.

         17.    A fund may not concentrate the investments of the fund in a
                single industry nor invest more than 25% of the current value of
                its total assets in a single industry.

         18.    A fund may not sell call or put options, or purchase call or
                put options, except that (a) the Gateway Fund may (i) sell
                covered call options with respect to all of its portfolio
                securities or with respect to securities indexes; (ii)
                purchase exchange-traded put and call options, provided that
                after any such purchase not more than 5% of the Fund's net
                assets would be invested in premiums on the purchase of put
                and call options or combinations thereof; (iii) sell covered
                put options, provided that after any such sale the Gateway
                Fund would not have more than 50% of its total assets (taken
                at current value) subject to being invested on the exercise of
                put options; and (iv) enter into closing purchase transactions
                with respect to such options, and (b) the Small Cap Index Fund
                may purchase exchange-traded puts and calls provided that
                after any such purchase not more than 5% of the Fund's assets
                would be invested in premiums on the purchase of such options.

         The Trust has no fundamental policy with respect to the issuance of
senior securities by any fund; however, the Investment Company Act of 1940
prohibits the Trust's issuance of any such securities.

         In addition to these fundamental policies:
         -      Each fund will limit its investment in warrants to no more than
                5% of such fund's assets. The Adviser has no current intention
                of causing any fund to invest in warrants in the coming year.
         -      No fund will purchase additional portfolio securities while
                borrowings in excess of 5% of the fund's total assets are
                outstanding. The Adviser has no current intention of causing any
                fund to borrow in excess of 5% of the funds total assets in the
                coming year.

                        PERFORMANCE AND RISK INFORMATION
                        --------------------------------

PERFORMANCE INFORMATION

         The Funds may quote performance in various ways. All performance
information supplied by the Funds is based upon historical results and is not
intended to indicate future performance. Total returns and other performance
information may be shown numerically or in a table, graph, or similar
illustration. A fund's share prices and total returns fluctuate in response to
market conditions, interest rates, and other factors.



                                       10
<PAGE>   47

         TOTAL RETURN CALCULATIONS
         -------------------------
         Total returns reflect all aspects of a fund's return, including the
effect of reinvesting dividends and capital gain distributions, and any change
in a fund's net asset value per share (the "NAV") over the period.

         Average annual total returns are calculated by determining the average
annual compounded rates of return over one-, five-, and ten-year periods that
would equate an initial hypothetical investment to the ending redeemable value
calculated according to the following formula:

P (1 + T) to the nth power = ERV where     T     =  Average annual total return
                                           N     =  Number of years and portion
                                                    of a year
                                           ERV   =  Ending redeemable value (of
                                                    an initial hypothetical
                                                    $1,000 investment) at the
                                                    end of the period
                                           P     =  $1,000 (the hypothetical
                                                    initial investment)

         If a fund has been in existence for less than one, five, or ten years,
the time period since the date it commenced operations will be substituted for
the periods stated.

         As a hypothetical example, a cumulative return of 100% growth on a
compounded basis in ten years would produce an average annual total return of
7.18%, which is the annual rate that would equal 100% growth on a compounded
basis in ten years. While average annual total returns are convenient means of
comparing investment alternatives, investors should realize that a fund's
performance is not constant over time, but changes from year to year, and that
average annual total returns represent averaged figures as opposed to the actual
year-to-year performance of the fund.

         Average annual total return is calculated as required by applicable
regulations promulgated by the SEC. In addition to average annual total returns,
a fund may quote year-by-year total returns and cumulative total returns
reflecting the simple change in value of any investment over a stated period.
Average annual, year-by-year, and cumulative total returns may be quoted as a
percentage or as a dollar amount.



         HISTORICAL RESULTS
         ------------------
         The following table shows each fund's average annual and cumulative
total returns for the period ended December 31, 1999:
<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------

     AVERAGE ANNUAL TOTAL RETURN          ONE YEAR      FIVE YEARS     TEN YEARS      LIFE OF FUND
- -----------------------------------------------------------------------------------------------------
<S>                                         <C>           <C>             <C>             <C>
Gateway Fund                                12.97%        11.83%          10.48%          10.61%
Gateway Small Cap Index Fund                29.12         16.49%          N/A             12.38%
- -----------------------------------------------------------------------------------------------------
</TABLE>
<TABLE>
<CAPTION>

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

       CUMULATIVE TOTAL RETURN            ONE YEAR       FIVE YEARS    TEN YEARS      LIFE OF FUND
- -----------------------------------------------------------------------------------------------------
<S>                                         <C>           <C>            <C>              <C>
Gateway Fund                                12.97%        74.86%         170.91%          826.820%
Gateway Small Cap Index Fund                29.12         114.54%         N/A             114.80%
- -----------------------------------------------------------------------------------------------------
</TABLE>

         The table below shows the redeemable value on December 31, 1999, for an
initial investment of $10,000 in the fund that was made at the beginning of the
one-, five-, and ten-year periods, or at the commencement of the fund's
operations. The table assumes all dividends and distributions have been
reinvested in additional fund shares.
<TABLE>
<CAPTION>

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

                                          ONE YEAR       FIVE YEARS    TEN YEARS      LIFE OF FUND
- -----------------------------------------------------------------------------------------------------
<S>                                       <C>             <C>           <C>              <C>
Gateway Fund                              $11,297         $17,486       $27,091          $92,682
</TABLE>






                                       11
<PAGE>   48


<TABLE>

<S>                                       <C>             <C>                            <C>
Gateway Small Cap Index Fund              $12,912         $21,454         N/A            $21,148
- -----------------------------------------------------------------------------------------------------
</TABLE>


RISK INFORMATION

         In evaluating the performance of any investment including a Gateway
fund, it is important to understand the risks involved in the investment.
Information regarding the performance of an investment, while valuable in
itself, is more meaningful when it is related to the level of risk associated
with that investment. Thus, two different mutual funds that produce similar
average annual total returns may present markedly different investment
opportunities if the risk of loss associated with one mutual fund is greater
than that of the other mutual fund.

         For example, an investment in a mutual fund that invests in stocks
generally will present greater potential for variation in the share price of the
mutual fund, and hence a greater risk of gain or loss than an investment in a
mutual fund that invests in short-term U. S. government securities. Because the
potential for greater gain typically carries with it a greater degree of risk,
the advisability of an investment in a particular mutual fund for a given
investor will depend not only on historical performance of the fund but also on
the potential for gain and loss associated with that mutual fund.

         The Gateway Trust offers three different funds that produce different
total returns and present different risk potentials. The difference in risk
potential can be demonstrated by various statistical concepts. The following
statistical concepts can be used to measure some of the risks associated with an
investment in each fund.


         COMPARATIVE INDEXES
         The performance and risk of the Gateway Fund and the Small Cap Index
Fund may be compared to various broadly recognized indexes such as the S&P 500
Index or the Lehman Government/Corporate Bond Index. These comparative indexes
are used because they are the standard benchmarks of the stock market and bond
market respectively. A fund's performance and risk may also be compared to other
appropriate indexes. The following is a description of some of the indices that
may be used:
          The S&P 100 Index is an unmanaged index of 100 common stocks with a
market capitalization range of $980 million to $240 billion. The performance of
this index assumes reinvestment of all dividends paid on the stocks in the
index.
         The S&P 500 Index is a widely recognized measure of performance for the
stock market. The S&P 500 figures represent the prices of an unmanaged index of
500 common stocks and assume reinvestment of all dividends paid on the stocks in
the index.
         The Wilshire Small Cap Index is an unmanaged index of 250 common stocks
with a market capitalization range of $39 million to $3.2 billion. The
performance of this index assumes reinvestment of all dividends paid on the
stocks in the index.
         The Lehman Government/Corporate Bond Index is a widely recognized
measure of performance for the bond market representing an unmanaged index of
selected government and corporate bonds. The Lehman Index figures assume
reinvestment of all distributions paid on the bonds in the index. As of December
31, 1997, the average maturity of this index was 10.07 years.
         The Salomon Broad Investment-Grade Medium Term (1-10) Index in an
unmanaged index which features a blend of U.S. Treasury, government-sponsored
(U.S. Agency and supranational), mortgage and corporate securities limited to a
maturity of no more than ten years.
        The Consumer Price Index is a widely recognized measure of inflation
calculated by the U. S. government.
        U. S. Treasury bills are negotiable debt obligations of the U. S.
government. Since they are secured by the full faith and credit of the
government, they are regarded as risk-free investments. Treasury bills are
short-term securities with maturities of one year or less.


         STANDARD DEVIATION
         Standard deviation measures the volatility of the total return of a
fund. Standard deviation is one method of comparing the total return of a fund
to the average monthly total return of the fund. In general, a fund that has a
greater standard deviation is a fund that has displayed a greater tendency to
vary from its own average monthly total return. Standard deviation can also be
used to compare the total return of a fund to the total return of an index or
another mutual fund. By comparing the magnitude of the standard deviation of
each investment, an analyst is able to determine the relative volatility of each
investment.


         For example, as of December 31, 1999, the annual standard deviation for
the Gateway Fund over the past





                                       12
<PAGE>   49



three years was 4.97% while the standard deviation for the S&P 500 Index was
18.48%. Thus, the S&P 500 Index was approximately four times as volatile as the
Gateway Fund. An investment with an expected return of 10% and a standard
deviation of 15% would be expected to earn a total return ranging from -5% to
+25% about 68% of the time, a total return ranging from -20% to +40% about 95%
of the time, and a total return ranging from -35% to +55% about 97% of the time.





                                       13
<PAGE>   50



         BETA
         Beta analyzes the market risk of a fund by showing how responsive the
fund is to the market as defined by an index. Beta is a comparative measure of a
fund's volatility in relation to an appropriate index. Generally, higher betas
represent riskier investments. By definition, the beta of the market is 1.00.
Thus, a fund with a beta higher than 1.00 is expected to perform better than the
market in up markets and worse than the market in down markets.

         For example, the beta of the Gateway Fund was 0.29 for the five-year
period ended December 31, 1999. The Gateway Fund would be expected to perform
approximately 1/3 as well as the market (as defined by S&P 500 Index) in up
markets and 1/3 as poorly as the market in down markets. Beta is the slope of
the "least square line" which compares the fund with an index.


RANKINGS AND COMPARATIVE PERFORMANCE INFORMATION

         Each fund may compare its performance to that of other mutual funds or
categories of mutual funds as reported by independent services such as
Morningstar, Inc., Lipper Analytical Services, Inc., and Value Line Mutual Fund
Survey, or by other financial publications with a circulation of 10,000 readers
or more. Performance comparisons may be expressed as ratings, such as the
proprietary ratings published by Morningstar, Inc., or rankings, such as the
rankings of funds in various categories published by Lipper Analytical Services,
Inc. Performance comparisons may also be expressed as designations (such as a
certain number of "stars") or descriptions (such as "best fund") assigned by
such services or publications.

PORTFOLIO HOLDINGS

         Each fund may list their portfolio holdings from time to time.

                              SHAREHOLDER SERVICES
                              --------------------

         Gateway Investment Advisers, L.P. serves as the Trust's shareholder
servicing, transfer, dividend disbursing, and financial servicing agent (the
"Servicing Agent"). In this capacity, it performs various shareholder services
on behalf of the Trust.

OPEN ACCOUNT

         Each fund's regular account for investors who purchase its shares is
the Open Account. The Open Account facilitates regular purchases of fund shares
over a period of years and provides the option of receiving dividends and
distributions either in cash or in fund shares. Gateway does not charge for the
automatic reinvestment of dividends and distributions.

         The Servicing Agent maintains a record of the investor's purchases,
redemptions, and share balances in the investor's Open Account. Shortly after
each purchase, the Servicing Agent will mail a confirmation to the investor
showing the shares purchased, the exact price paid for the shares, and the total
number of shares owned. Share certificates will not be issued.

         Upon opening an account, the investor may elect either of the following
options: (1) reinvestment at net asset value of all distributions, or (2)
payment in cash of all distributions. If no election is made, all distributions
will be reinvested at net asset value. An election may be changed by a letter or
telephone call to the Servicing Agent. No annual maintenance fees are charged by
the Trust on any Open Account. The Trust reserves the right to charge annual
fees in the future. Shareholders will be notified of any change in the annual
fee arrangement.



                                       14
<PAGE>   51


AUTOMATIC INVESTMENT PROGRAM

         Investors can arrange to use our Automatic Investment Program by either
making the election on the New Account Application or by contacting Shareholder
Services at (800) 354-6339 for the appropriate forms. With this service,
investors purchase additional shares by having a predetermined amount of $100 or
more automatically transferred from a bank account to the Trust on a monthly or
quarterly basis. Changes to an Automatic Investment Program, including
discontinuing participation, must be in writing and sent to The Gateway Trust,
Shareholder Services, P. O. Box 5211, Cincinnati, OH 45201-5211. All changes to
the Program must be received by Gateway at least five business days prior to the
next scheduled transfer.

IRAS

         Investors may purchase shares of any Gateway fund through Individual
Retirement Accounts ("IRAs") which are permitted to invest in shares of a mutual
fund. The Trust itself sponsors a traditional IRA (the "Gateway Traditional
IRA") and a Roth IRA (the "Gateway Roth IRA") (or jointly as a "Gateway IRA"). A
Gateway IRA can be adopted by an investor and is specifically designed to permit
the investor to invest in shares of any Gateway fund selected by the investor.
The custodian of the Gateway IRA is Firstar Bank, N.A. Investors can obtain
forms to establish a Gateway IRA by calling Shareholder Services at (800)
354-6339.

         An IRA is a special program with certain tax benefits that generally
permits an investor to establish and contribute to his or her own retirement
plan. For detailed information about a Gateway IRA, please refer to the
Agreement and Disclosure Statement for the appropriate Gateway IRA. Agreements
and Disclosure Statements can be obtained by calling Shareholder Services at
(800) 354-6339.

         An investor may make a direct transfer of assets from one IRA to a
Gateway IRA by directing the existing IRA custodian or trustee to transfer
directly to a Gateway IRA the amount held in that prior IRA, without directly
receiving those funds or being taxed on the transfer. There is no minimum
holding period for a direct transfer of IRA assets from one custodian or trustee
to another. Call Shareholder Services at (800) 354-6339 to obtain the
appropriate transfer form.

         A Gateway Traditional IRA is eligible to receive direct rollovers of
distributions from a qualified employer plan. An investor can make a direct
rollover by instructing the employer's plan to wire the distribution to Firstar
Bank, N.A. as custodian for the Gateway Traditional IRA. The distribution should
be wired to:

                  The Gateway Trust c/o Firstar Bank, N.A.
                  ABA #042-0000-13
                  Cincinnati, OH
                  Name (insert investor name)
                  Gateway Account No. (insert investor account number)
                  Name of Gateway fund(s) in which you wish to invest

         An investor can also make a direct rollover to a Gateway Traditional
IRA by instructing the employer's plan to prepare a check for the amount to be
rolled over payable to "Firstar Bank, N.A., as Custodian of Individual
Retirement Account of (insert investor name)," and sending that check to
Gateway. The check can also be delivered in person to Gateway, or mailed to:

                  The Gateway Trust
                  Shareholder Services
                  P. O. Box 5211
                  Cincinnati, OH  45201-5211

         An investor can make a 60-day rollover of a distribution from a
qualified employer plan by instructing the employer's plan to prepare a check
payable to the investor and by endorsing or cashing the check and depositing
some or all of the proceeds in a Gateway Traditional IRA. The deposit must be
delivered in person to Gateway, or mailed to The Gateway Trust at the above
address within 60 days of when the investor receives the distribution. The
employer's plan must withhold 20% of the taxable amount for federal income tax
if the investor chooses a 60-day rollover for the distribution.
         Some portions of distributions from other IRAs or from tax-qualified
profit sharing, stock bonus, pension, or annuity plans are not eligible for
regular or direct rollovers. For instance, distributions of nontaxable after-



                                       15
<PAGE>   52

tax employee contributions or required minimum payments made after an individual
reaches age 70 1/2 cannot be rolled over.

         To make a withdrawal from a Gateway IRA, an investor should contact
Shareholder Services at (800) 354-6339.

         The rules for contributing to, investing under, and distributing from
IRAs are complex, and any investor should consult with his or her own tax
adviser if he or she has any questions with respect to IRAs and to determine if
there have been any recent changes to the rules. At the time an IRA is
established, the custodian or trustee of the IRA is required by law to provide a
disclosure statement to the individual setting forth important information
concerning IRAs.

         Further information concerning IRAs can be obtained from any district
office of the Internal Revenue Service. In particular, Publication 590 of the
Internal Revenue Service provides general information as to IRAs.

         No annual maintenance fees are charged by the Trust for any account,
including IRAs, SEP-IRAs, retirement, and pension or profit-sharing plans,
including 401(k) plans. The Trust reserves the right to charge annual fees in
the future. Shareholders will be notified of any change in the annual fee
arrangement.

SYSTEMATIC WITHDRAWAL PROGRAM

         If the value of a shareholder's account is at least $5,000, the
shareholder can request withdrawals on either a monthly or a quarterly basis in
the minimum amount of $100. The Trust makes no recommendation as to the minimum
amount to be periodically withdrawn by a shareholder. A sufficient number of
shares in the shareholder's account will be sold periodically (normally one
business day prior to each withdrawal payment date) to meet the requested
withdrawal payments.

         If a shareholder participates in the Systematic Withdrawal Program, all
dividends and distributions on shares held in the account will be reinvested in
additional shares at net asset value. Since the withdrawal payments represent
the proceeds from sales of the fund shares, there will be a reduction, and there
could even be an eventual depletion, of the amount invested in the funds to the
extent that withdrawal payments exceed the dividends and distributions paid and
reinvested in shares. Withdrawals under the Systematic Withdrawal Program should
not, therefore, be considered a yield on investment. A shareholder can make
arrangements to use the Systematic Withdrawal Program (or discontinue
participation) by contacting Shareholder Services at (800) 354-6339.

                 ADDITIONAL PURCHASE AND REDEMPTION INFORMATION
                 ----------------------------------------------

         Shares of all funds are purchased and redeemed at their net asset value
as next determined following receipt of the purchase order or redemption notice.
Redemptions under the Systematic Withdrawal Program and installment
distributions from IRAs are effected at the net asset value next determined on
or after the date designated for the redemption or distribution.

         Certificates for shares of any fund will not be issued.

         The minimum initial investment is $1,000 ($500 for IRAs). The minimum
additional investment is $100, subject to certain exceptions such as investments
by the Adviser's employees, by participants in an SEP-IRA program, and by
participants in the Automatic Investment Program. The Trust reserves the right
to accept or reject any purchase order of any fund.

         There is no minimum or maximum applicable to redemption of shares of
any fund. The Trust, however, reserves the right to redeem a shareholder's
account(s) under certain circumstances. The shareholder will receive at least 60
days' written notice prior to the redemption of the account(s).

         The Trust may redeem a shareholder's account(s) in any fund when the
aggregate value of the shareholder's account(s) falls below $800 (other than as
a result of market action). The shareholder may prevent such redemption by
increasing the value of the account(s) to $1,000 or more within the 60-day
period.

         The Trust will redeem a shareholder's account if the shareholder does
not provide a valid U. S. social security number or taxpayer identification
number or other requested documents. The shareholder may



                                       16
<PAGE>   53

prevent such redemption by providing the requested information within the 60-day
period.

         The Trust reserves the right to terminate temporarily or permanently
the exchange privilege for any shareholder who makes an excessive number of
exchanges between funds. The shareholder will receive written notice that the
Trust intends to limit the shareholder's use of the exchange privilege.
Generally the Trust limits a shareholder to twelve exchange transactions per
calendar year. Accounts under common ownership or control, including accounts
with the same taxpayer identification number, normally will be counted as one
account for purposes of the exchange limit.

         The Trust also reserves the right to terminate or modify the exchange
privilege or to refuse an exchange if the exchange would adversely affect a fund
involved in the exchange.

         Signature guarantees are required for all redemptions, (on the date of
receipt by the servicing agent of all necessary documents), regardless of the
amount involved, when the proceeds are to be paid to someone other than the
registered owner(s). The signature guarantee requirement may be waived by the
Trust in certain instances. The Trust also reserves the right to require a
signature guarantee on any instructions or redemptions given to the Trust for
any reason. The purpose of signature guarantees is to prevent fraudulent
redemptions which could result in losses to the Trust, the servicing agent, or
shareholders. A signature guarantee will be accepted from banks, brokers,
dealers, municipal securities dealers or brokers, government securities dealers
or brokers, credit unions (if authorized by state law), national securities
exchanges, registered securities associations, clearing agencies, and savings
associations. Notary publics are unacceptable guarantors. The signature
guarantees must appear either (a) on the written request for redemption; (b) on
a stock power which should specify the total number of shares to be redeemed; or
(c) on all stock certificates tendered for redemption.

         The right of redemption may be suspended or the date of payment
postponed (a) for any periods during which the New York Stock Exchange is closed
(other than for customary weekend and holiday closings); (b) when trading in any
of the markets which a fund normally utilizes is restricted as determined by the
SEC; (c) if any emergency exists as defined by the SEC so that disposal of
investments or determination of a fund's net asset value is not reasonably
practicable; or (d) for such other periods as the SEC by order may permit for
protection of the Trust's shareholders.

         The Trust has elected to be governed by Rule18f-1 of the Investment
Company Act which obligates each fund to redeem shares in cash with respect to
any one shareholder during any 90-day period up to the lesser of $250,000 or 1%
of the assets of the fund. Although payment for redeemed shares generally will
be made in cash, under abnormal circumstances the Board of Trustees of the Trust
may determine to make payment in securities owned by the fund. In such event,
the securities will be selected in such manner as the Board of Trustees deems
fair and equitable, in which case brokerage and other costs may be incurred by
such redeeming shareholders in the sale or disposition of their securities. To
date, all redemptions have been made in cash.

         The Trust reserves the right to modify or terminate any purchase,
redemption, or other shareholder service procedure upon notice to shareholders.

         Purchases and redemptions generally may be effected only on days when
the stock and options exchanges are open for trading. These exchanges are closed
on Saturdays and Sundays and the following holidays: New Year's Day, Martin
Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day, Independence
Day, Labor Day, Thanksgiving, and Christmas Day.

                     INVESTMENT ADVISORY AND OTHER SERVICES
                     --------------------------------------

GATEWAY INVESTMENT ADVISERS, L.P.

         Gateway Investment Advisers, L.P., (the "Adviser"), a Delaware limited
partnership, has acted as the investment adviser for the funds since December
15, 1995. Gateway Investment Advisers, Inc. ("GIA") provided investment advisory
services to the funds from their formation until December 15, 1995. The Adviser
became the successor in interest to the assets, business, and personnel of GIA
which was organized in June 1977. GIA is the general partner of the Adviser with
a 76% ownership interest, while Alex. Brown Investments Incorporated ("ABII") is
a limited partner with a 15% ownership interest. ABII is an affiliate of DB
Alex. Brown LLC, a nationally known investment banking firm and registered
broker/dealer located in Baltimore, Maryland. Walter G. Sall, Chairman and a
Trustee of the Trust, and J. Patrick Rogers, the portfolio manager of the Funds,
and




                                       17
<PAGE>   54



President and a Trustee of the Trust, together own of record and beneficially
99.85% of the outstanding shares of GIA and thereby control the Adviser. Mr.
Sall is Chairman and a director of GIA and Mr. Rogers is its President and a
director. The third director of GIA is Margaret-Mary V. Preston who is employed
by DB Alex. Brown LLC as a Managing Director.



GATEWAY FUND MANAGEMENT AGREEMENT

         The Trust has retained the Adviser under an investment advisory
contract (the "Management Agreement") to act as investment manager and in such
capacity supervise the investments of the Gateway Fund, subject to the policies
and control of the Trust's Board of Trustees. The Management Agreement for the
Gateway Fund became effective January 1, 1999. Services were provided by the
Adviser under an investment advisory contract beginning December 15, 1995, and
previously by GIA under a similar contract prior to December 15, 1995.

         Pursuant to the Management Agreement, the Adviser, at its sole expense,
provides the Fund with (i) investment recommendations regarding such fund's
investments; (ii) office space, telephones, and other office equipment; and
(iii) clerical and secretarial staff and the services, without additional
compensation, of all officers of the Trust. In addition, the Adviser has agreed
to bear (i) expenses incurred in connection with association membership dues,
except the annual dues of the Trust for its membership in the Investment Company
Institute, which shall be paid by the Trust; (ii) expenses of printing and
distributing all Fund registration statements, prospectuses and reports to
current Fund shareholders; (iii) costs of printing and transmitting reports to
governmental agencies; and (iv) printing and mailing costs. The Management
Agreement further provides that under certain circumstances the Adviser may
cause each fund to pay brokerage commissions in order to enable the Adviser to
obtain brokerage and research services for its use in advising such fund and the
Adviser's other clients, provided that the amount of commission is determined by
the Adviser, in good faith and in the best interests of the Fund, to be
reasonable in relation to the value of the brokerage and research services
provided.

         The Management Agreement provides that all expenses not specifically
assumed by the Adviser which may be incurred in the operation of the Trust and
the offering of its shares will be borne by the Trust. Such expenses will be
allocated among the Funds in the Trust by direction of the Board of Trustees,
most frequently on the basis of expenses incurred by each fund, but where that
is not practicable on such basis as the Trustees determine to be appropriate.
Expenses to be borne by the Trust include:

   -     expenses of continuing the Trust's existence;
   -     fees and expenses of trustees not employed by the Adviser;
   -     expenses incurred by the Fund pursuant to the Fund's Distribution Plan;
   -     expenses of registering or qualifying the Trust or its shares under
         federal and various state laws and maintaining and updating such
         registrations and qualifications on a current basis;
   -     interest expenses, taxes, fees, and commissions of every kind; expenses
         of issue, including cost of share certificates;
   -     repurchases and redemption of shares;
   -     charges and expenses of custodians, transfer agents, fund accountants,
         shareholder servicing agents, dividend disbursing agents, and
         registrars;
   -     expenses of valuing shares of each fund;
   -     auditing, accounting, and legal expenses;
   -     expenses of shareholder meetings and proxy solicitations therefore;
   -     insurance expenses;
   -     membership fees of the Investment Company Institute;
   -     and all "extraordinary expenses" as may arise, including all losses and
         liabilities in administrating the Trust; expenses incurred in
         connection with litigation proceedings and claims and the legal
         obligations of the Trust to indemnify its officers, trustees, and
         agents with respect thereto.

         A majority of the Board of Trustees of the Trust and a majority of the
trustees who are not "interested persons" (as defined in the Investment Company
Act of 1940) of any party to the Adviser Contracts, voting separately, shall
determine which expenses shall be characterized as "extraordinary expenses."

         In return for the services and facilities furnished by the Adviser
under the Management Agreement, the Gateway Fund pays the Adviser a management
fee (the "Management Fee") at (a) the annual rate of 0.925% of the average value
of the daily net assets of the Fund; minus (b) the amount of the Fund's expenses
incurred pursuant to its Distribution Plan. In addition, as long as the Adviser
is providing transfer agency, fund



                                       18
<PAGE>   55

accounting, and other services pursuant to the Services Agreement with the Trust
dated January 1, 1998, the Adviser shall receive no separate compensation for
such services with respect to the Gateway Fund during the term of the Management
Agreement.

         If total expenses of the Fund for any fiscal year (including the
Adviser's compensation, but exclusive of taxes, interest, brokerage commissions,
and any "extraordinary expenses" determined as above described) exceed the
specified percentage of the Fund's average daily net asset value for such year,
the Management Agreement requires the Adviser to bear all such excess expenses
up to the amount of the Management Fee. The applicable expense limitation
percentage for the Fund is 1.50% of the Fund's average daily net asset value.
Each month the Management Fee is determined and the Fund's expenses are
projected. If the Fund's projected expenses are in excess of the above-stated
expense limitations, the Management Fee paid to the Adviser will be reduced by
the amount of the excess expenses, subject to an annual adjustment; provided,
however, that the aggregate annual reduction from the Adviser to the Fund shall
not exceed the aggregate Management Fee paid by the Fund to the Adviser for the
year.

GATEWAY SMALL CAP INDEX FUND INVESTMENT ADVISORY CONTRACT

         The Trust has retained the Adviser under an investment advisory
contract (the "Adviser Contract") to act as investment manager and in such
capacity supervise the investments of the Gateway Small Cap Index Fund, subject
to the policies and control of the Trust's Board of Trustees. The Adviser
Contract for the Small Cap Index Fund became effective December 15, 1995.
Services were provided by GIA under a substantially identical contract prior to
this date.

         Pursuant to the Adviser Contract, the Adviser, at its sole expense,
provides the Fund with (i) investment recommendations regarding such fund's
investments; (ii) office space, telephones, and other office equipment; and
(iii) clerical and secretarial staff and the services, without additional
compensation, of all officers of the Trust. In addition, the Adviser has agreed
to bear (i) advertising and other marketing expenses in connection with the sale
of the shares of the funds; (ii) expenses of printing and distributing
prospectuses and related documents to prospective shareholders; and (iii)
association membership dues (other than for the Investment Company Institute).
The Adviser Contract further provides that under certain circumstances the
Adviser may cause each fund to pay brokerage commissions in order to enable the
Adviser to obtain brokerage and research services for its use in advising such
fund and the Adviser's other clients, provided that the amount of commission is
determined by the Adviser, in good faith and in the best interests of the Fund,
to be reasonable in relation to the value of the brokerage and research services
provided.

         The Adviser Contract provides that all expenses not specifically
assumed by the Adviser which may be incurred in the operation of the Trust and
the offering of its shares will be borne by the Trust. Such expenses will be
allocated among the funds in the Trust by direction of the Board of Trustees,
most frequently on the basis of expenses incurred by each fund, but where that
is not practicable on such basis as the Trustees determine to be appropriate.
Expenses to be borne by the Trust include:

   -     fees and expenses of trustees not employed by the Adviser;
   -     expenses of printing and distributing prospectuses to current
         shareholders of the Trust;
   -     expenses pertaining to registering or qualifying the Trust or its
         shares under various federal and state laws, and maintaining and
         updating such registrations and qualifications;
   -     interest expense, taxes, fees, and commissions (including brokerage
         commissions) of every kind;
   -     expenses related to repurchases and redemptions of shares;
   -     charges and expenses of custodians, transfer agents, dividend
         disbursing agents, and registrars;
   -     expenses of valuing shares of each fund;
   -     printing and mailing costs other than those expressly assumed by the
         Adviser;
   -     auditing, accounting, and legal expenses;
   -     expenses incurred in connection with the preparation of reports to
         shareholders and governmental agencies;
   -     expenses of shareholder meetings and proxy solicitations;
   -     insurance expenses;
   -     all "extraordinary expenses" which may arise, including all losses and
         liabilities incurred in connection with litigation proceedings and
         claims, and the legal obligations of the Trust to indemnify its
         officers, trustees, and agents with respect thereto.




                                       19
<PAGE>   56

         A majority of the Board of Trustees of the Trust and a majority of the
trustees who are not "interested persons" (as defined in the Investment Company
Act of 1940) of any party to the Adviser Contracts, voting separately, shall
determine which expenses shall be characterized as "extraordinary expenses."

         In return for the services and facilities furnished by the Adviser
under the Adviser Contract, the Small Cap Index Fund pays the Adviser an
advisory fee (the "Advisory Fee") computed at an annual rate of 0.90% of the
first $50 million of the average daily net asset value of such fund, 0.70% of
such asset value in excess of $50 million and less than $100 million, and 0.60%
of such asset value in excess of $100 million.

         If total expenses of the Fund for any fiscal year (including the
Adviser's compensation, but exclusive of taxes, interest, brokerage commissions,
and any "extraordinary expenses" determined as above described) exceed the
specified percentage of the Fund's average daily net asset value for such year,
the Adviser Contract requires the Adviser to bear all such excess expenses up to
the amount of the Advisory Fee. The applicable expense limitation percentage for
the Fund is 2.00% of the Fund's average daily net asset value. Each month the
Advisory Fee is determined and the Fund's expenses are projected. If the Fund's
projected expenses are in excess of the above-stated expense limitations, the
Advisory Fee paid to the Adviser will be reduced by the amount of the excess
expenses, subject to an annual adjustment; provided, however, that the aggregate
annual reduction from the Adviser to the Fund shall not exceed the aggregate
Advisory Fee paid by the Fund to the Adviser for such year.


         The following table shows the Advisory Fees earned by the Adviser (or
GIA) for providing services to the funds under the then-current investment
advisory contracts. It also shows the amount of the fees waived by the Adviser
for the years ended December 31, 1999, 1998 and 1997.



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

      FEE AND WAIVER            GATEWAY FUND          SMALL CAP INDEX FUND
- -------------------------------------------------------------------------------
1999 Fee Earned                   $4,048,147                  $129,346
1999 FEE WAIVED                            0                    81,545
                                                                ------
1999 Fee Paid                     $4,048,147                   $47,801
                                                               -------
1998 Fee Earned                   $2,382,457                  $140,709
1998 Fee Waived                            0                    63,744
                            -----------------               ----------
1998 Fee Paid                     $2,382,547                 $  76,965
                                  ==========                 =========
- -------------------------------------------------------------------------------
1997 Fee Earned                   $1,530,637                  $118,875
1997 Fee Waived                            0                    73,783
                            -----------------               ----------
1997 Fee Paid                     $1,530,637                 $  45,092
                                  ==========                 =========
- -------------------------------------------------------------------------------


         The Management Agreement and the Adviser Contract further provide that
in the absence of willful misfeasance, bad faith, gross negligence, or reckless
disregard of its duties or obligations thereunder, the Adviser is not liable to
the Trust or any of its shareholders for any act or omission by the Adviser. The
Management Agreement and the Adviser Contract contemplate that the Adviser may
act as an investment manager or adviser for others.

         The Management Agreement and the Adviser Contract may be amended at any
time by the mutual consent of the parties thereto, provided that such consent on
the part of the Trust shall have been approved by the vote of a majority of the
Trust's Board of Trustees, including the vote cast in person by a majority of
the trustees who are not "interested persons" (as defined in the Investment
Company Act of 1940) of any party to the Adviser Contracts, and by vote of the
shareholders of the applicable fund.

         The Management Agreement and the Adviser Contract may be terminated,
upon 60 days' written notice (which notice may be waived) at any time without
penalty (i) by the Board of Trustees of the Trust; (ii) by the vote of a
majority of the outstanding voting securities of the applicable fund; or (iii)
by the Adviser. Both the Management Agreement and the Adviser Contract terminate
automatically in the event of assignment (as that term is defined in the
Investment Company Act of 1940) by the Adviser.


         The Management Agreement continues in effect until December 31, 2000
and the Adviser



                                       20
<PAGE>   57


Contract continues in effect until December 31, 2000, and thereafter, provided
that their continuance for the funds for each renewal year is specifically
approved in advance (i) by the Board of Trustees of the Trust or by vote of a
majority of the outstanding voting securities of the Funds, and (ii) by vote of
a majority of the trustees who are not parties to the Adviser Contracts or
"interested persons" of any party to the Management Agreement or the Adviser
Contract (other than as Trustees of the Trust) by votes cast in person at a
meeting specifically called for such purposes.


DISTRIBUTION PLAN FOR THE GATEWAY FUND


         A Distribution Plan pursuant to Rule 12b-1 under the Investment Company
Act (the "Plan") became effective on January 1, 1999 for the Gateway Fund. Under
the Plan, the Trust may, directly or indirectly, engage in any activities
related to the distribution of shares of the Fund, which activities may include,
but are not limited to, the following: (a) payments to securities dealers and
others that are engaged in the sale of shares, that may be advising shareholders
of the Fund regarding the Fund, that hold shares for shareholders in omnibus
accounts or as shareholders of record, or that provide shareholder support or
administrative services to the Fund and its shareholders; (b) expenses of
maintaining personnel who engage in or support distribution; (c) costs of
preparing, printing, and distributing prospectuses and statements of additional
information and reports of the Fund for recipients other than existing
shareholders of the Fund; (d) costs of formulating and implementing marketing
and promotional activities; and (e) costs of preparing, printing, and
distributing sales literature. The expenditures to be made by the Trust pursuant
to the Distribution Plan and the basis upon which payment of such expenditures
will be made is determined by the Trustees, but in no event may such
expenditures exceed in any fiscal year an amount calculated at the rate of 0.50%
of the average daily net asset value of the Fund. For 1999, expenses under the
Plan amounted to 0.31% of the average daily net asset value of the Fund.

         Any amendment that materially increases the amount of expenditures
permitted under the Plan must be approved by a vote of a majority of the
outstanding voting securities of the Gateway Fund. The Plan may be terminated at
any time by the vote of a majority of (i) the Trustees who are not "interested
persons" of the Trust (as defined in the Investment Company Act) and who have no
direct or indirect financial interest in the operation of the Plan or (ii) the
outstanding voting securities of the Gateway Fund. The Adviser, and Walter G.
Sall, J. Patrick Rogers and the other officers of the Trust (because of their
respective associations with the Adviser), may indirectly benefit from any
payments made pursuant to the Plan.

         It is anticipated that the Plan will significantly enhance the Fund's
ability to expand distribution which, in turn, will increase the overall assets
of the Fund, thus realizing further economies of scale which ultimately benefit
Fund shareholders.


CUSTODIAN

         Firstar Bank, N.A., 425 Walnut Street, Cincinnati, OH 45202, acts as
custodian of the Trust's assets (the "Custodian"). Under Custody Agreements with
the Funds, the Custodian holds the Funds' securities and keeps all necessary
accounts and records The Custodian has no part in determining the investment
policies of any fund or which securities are to be purchased or sold by any
fund.

SHAREHOLDER SERVICING, TRANSFER, DIVIDEND DISBURSING, AND FINANCIAL SERVICING
AGENT

         The Adviser is the Trust's Shareholder Servicing, Transfer, Dividend
Disbursing, and Financial Servicing Agent (the "Servicing Agent"). The Adviser's
mailing address for its activities as Servicing Agent is The Gateway Trust, 400
TechneCenter Drive, Suite 220, Milford, OH 45150. As Transfer Agent for the
Trust, the Servicing Agent's general duties include transferring shares,
processing applications for new accounts, depositing the payments for the
purchase of fund shares with the Custodian, and notifying the Trust and
Custodian of such deposits. The Servicing Agent opens and maintains a bookshare
account for each shareholder as set forth in the subscription application,
maintains records of each shareholder account, and sends confirmation of shares
purchased to each shareholder. The Servicing Agent also receives and processes
requests by shareholders for redemption of shares. If the shareholder request
complies with the redemption standards of the Trust, the Servicing Agent will
direct the Custodian to pay the appropriate redemption price. If the redemption
request does not comply with such standards, the Servicing Agent will promptly
notify the shareholder of the reasons for rejecting the



                                       21
<PAGE>   58

redemption request.

         As the Dividend Disbursing Agent for the Trust, the Servicing Agent,
upon notification of the declaration of a dividend or distribution, will
determine the total number of shares issued and outstanding as of the record
date for the dividend or distribution and the amount of cash required to satisfy
such dividend or distribution. The Servicing Agent will prepare and mail to
shareholders dividend checks in the amounts to which they are entitled. In the
case of shareholders participating in the dividend reinvestment plan, the
Servicing Agent will make appropriate credits to their bookshare accounts.
Shareholders will be notified by the Servicing Agent of any dividends or
distributions to which they are entitled, including any amount of additional
shares purchased with their dividends. In addition, the Servicing Agent will
prepare and file with the Internal Revenue Service and with any state, as
directed by the Trust, returns for reporting dividends and distributions paid by
such fund.

         The Servicing Agent, as the Shareholder Servicing Agent, will open and
maintain any plan or program for shareholders in accordance with the terms of
such plans or programs (see "SHAREHOLDER SERVICES" herein). With regard to the
Systematic Withdrawal Program, the Servicing Agent will process such Systematic
Withdrawal Program orders as are duly executed by shareholders and will direct
appropriate payments to be made by the Custodian to the shareholder. In
addition, the Servicing Agent will process such accumulation plans, group
programs, and other plans or programs for investing shares as provided in the
Funds' current prospectuses.


         The Small Cap Index Fund reimburses the Servicing Agent for printing,
mailing, and compliance expenses. The Gateway Fund reimburses the Servicing
Agent for compliance expenses. The Small Cap Index Fund compensates the
Servicing Agent for these services at a fixed rate of $4,000 per month, plus the
greater of $2,500 per month or an annual rate of 0.20% of the Fund's average net
assets. Beginning January 1, 1999, pursuant to the Gateway Fund Management
Agreement, the Servicing Agent receives no compensation for its services to
Gateway Fund. For the year ended December 31, 1999, the Adviser was paid
$173,196 in its capacity as Servicing Agent to the Gateway Small Cap Index Fund
and the Cincinnati Fund.


                                    BROKERAGE
                                    ---------

         Transactions on stock and option exchanges involve the payment of
negotiated brokerage commissions. In the case of securities traded in the
over-the-counter market, there is generally no stated commission but the price
usually includes an undisclosed commission or mark-up.

         In effecting portfolio transactions for each fund, the Adviser is
obligated to seek best execution, which is to execute a fund's transaction where
the most favorable combination of price and execution services are available
("best execution"), except to the extent that it may be permitted to pay higher
brokerage commissions for brokerage and research services as described below. In
seeking best execution, the Adviser, in each fund's best interest, considers all
relevant factors, including:

     -   price;
     -   the size of the transaction;
     -   the nature of the market for the security;
     -   the amount of commission;
     -   the timing of the transaction taking into account market prices and
         trends;
     -   the reputation, experience, and financial stability of the
         broker-dealer involved;
     -   the quality of service rendered by the broker-dealer in other
         transactions.

         Consistent with the Rules of Fair Practice of the National Association
of Securities Dealers, Inc. and subject to seeking best execution and such other
factors as the Trustees may determine, the Adviser may consider sales of shares
of a fund as a factor in the selection of broker-dealers to execute securities
transactions for such fund. Closing option transactions are usually effected
through the same broker-dealer that executed the opening transaction.


         The Trust has no obligation to deal with any broker or dealer in the
execution of its transactions. However DB Alex. Brown LLC, or any of its
affiliates ("Alex. Brown"), in its capacity as a registered broker-dealer, has,
from time to time, and will effect securities transactions which are executed on
a national securities exchange and over-the-counter transactions conducted on an
agency basis. Such transactions are executed at competitive commission rates.





                                       22
<PAGE>   59

         Transactions in the over-the-counter market can be placed directly with
market makers who act as principals for their own account and include mark-ups
in the prices charged for over-the-counter securities. Transactions in the
over-the-counter market can also be placed with broker-dealers who act as agents
and charge brokerage commissions for effecting over-the-counter transactions.
The Trust may place its over-the-counter transactions either directly with
principal market makers, or with broker-dealers if that is consistent with the
Adviser's obligation to obtain best qualitative execution. Under the Investment
Company Act of 1940, persons affiliated with an affiliate of the Adviser (such
as Alex. Brown) may be prohibited from dealing with the Trust as a principal in
the purchase and sale of securities. Therefore, Alex. Brown will not serve as
the Trust's dealer in connection with over-the-counter transactions. However,
Alex. Brown may serve as the Trust's broker in over-the-counter transactions
conducted on an agency basis and will receive brokerage commissions in
connection with such transactions.

         The Trust will not effect any brokerage transactions in its portfolio
securities with Alex. Brown if such transactions would be unfair or unreasonable
to the Trust's shareholders, and the commissions will be paid solely for the
execution of trades and not for any other services. In determining the
commissions to be paid to Alex. Brown, it is the policy of the Trust that such
commissions will, in the judgment of the Trust's Board of Trustees, be (a) at
least as favorable to the Trust as those which would be charged by other
qualified brokers having comparable execution capability, and (b) at least as
favorable to the Trust as commissions contemporaneously charged by Alex. Brown
on comparable transactions for its most favored unaffiliated customers, except
for customers of Alex. Brown considered by a majority of the Trust's
disinterested trustees not to be comparable to the Trust. The disinterested
trustees from time to time review, among other things, information relating to
the commissions charged by Alex. Brown to a fund and its other customers, and
other information concerning the commissions charged by other qualified brokers.
It is not contemplated that brokerage transactions will be effected exclusively
through Alex. Brown. The Adviser may from time to time use other brokers,
including brokers that provide research services as discussed below.

         While the Adviser does not intend to limit the placement of orders to
any particular broker or dealer, the Adviser generally gives preference to those
brokers or dealers who are believed to give best execution at the most favorable
prices and who also provide research, statistical, or other services to the
Adviser and/or the Trust. Commissions charged by brokers who provide these
services may be higher than commissions charged by those who do not provide
them. Higher commissions are paid only if the Adviser determines that they are
reasonable in relation to the value of the services provided, and it has
reported to the Board of Trustees of the Trust on a periodic basis to that
effect. The availability of such services was taken into account in establishing
the Advisory Fee. Specific research services furnished by brokers through whom
the Trust effects securities transactions may be used by the Adviser in
servicing all of its accounts. Similarly, specific research services furnished
by brokers who execute transactions for other Adviser clients may be used by the
Adviser for the benefit of the Trust.


         The Adviser has an agreement with Bridge Information Systems, Inc.
("Bridge") and an agreement with S&P Securities to direct brokerage transactions
to them in exchange for research services provided to the Adviser. For the
fiscal year ended December 31, 1999, the Trust paid brokerage commissions to
Bridge of $171,451 for effecting brokerage transactions totaling $_________.
During the same period, the Trust paid brokerage commissions to S&P Securities
of $25,840 for effecting brokerage transactions totaling $_________. The Adviser
may from time to time enter into similar agreements with other brokers.


         The Adviser Contracts provide that, subject to such policies as the
Trustees may determine, the Adviser may cause a fund to pay a broker-dealer who
provides brokerage and research services to the Adviser an amount of commission
for effecting a securities transaction for such fund in excess of the amount of
commission which another broker-dealer would have charged for effecting that
transaction. As provided in Section 28(e) of the Securities Exchange Act of
1934, "brokerage and research services" include:

     -   advice as to the value of securities, the advisability of investing in,
         purchasing, or selling securities, and the availability of securities,
         or purchasers, or sellers of securities;

     -   furnishing analyses and reports concerning issuers, industries,
         securities, economic factors and trends, portfolio strategy, and
         performance of accounts;

     -   effecting securities transactions and performing functions incidental
         thereto (such as clearance and settlement);

     -   services that provide lawful and appropriate assistance to the Adviser
         in the performance of its investment decision-making responsibilities.



                                       23
<PAGE>   60



         The following table shows the brokerage commissions paid by the funds
in the years ended December 31, 1999, 1998 and 1997.
<TABLE>
<CAPTION>

- ------------------------------------------------------------------------------------------------
       NAME OF FUND           1999 COMMISSIONS       1998 COMMISSIONS       1997 COMMISSIONS
- ------------------------------------------------------------------------------------------------
<S>                                 <C>                 <C>                       <C>
Gateway Fund                        $936,090            $1,052,719                $570,068
Small Cap Index Fund                 $33,366             $  22,665             $    24,496
- ------------------------------------------------------------------------------------------------
</TABLE>

         The increased level paid by the Gateway Fund from 1997 through 1999 is
attributable to an overall increase in total assets during those years.

         The Gateway Fund paid a total of $53,971 of brokerage commissions to DB
Alex. Brown LLC for the year ended December 31, 1999 or 5.8% of the entire
amount of commissions paid to all brokers for this Fund. The aggregate amount of
transactions involving the payment of these commissions is $67,259,823, or 6.5%
of the entire amount of transactions effected through all brokers combined for
this Fund. For the same year, The Gateway Fund paid a total of $300,760 of
brokerage commissions to Deutsche Bank or 32.1% of the entire amount of
commissions paid to all brokers for this Fund. The aggregate amount of
transactions involving the payment of these commissions is $256,087,206, or
24.7% of the entire amount of transactions effected through all brokers combined
for this Fund. The Gateway Fund paid a total of $258,373 of brokerage
commissions to BT Alex. Brown Incorporated for the year ended December 31, 1998
or 24.5% of the entire amount of commissions paid to all brokers for this Fund.
The aggregate amount of transactions involving the payment of these commissions
is $215,686,511, or 31% of the entire amount of transactions effected through
all brokers combined for this Fund. For the year ended December 31, 1997, the
Fund paid a total of $1,750 of brokerage commissions to BT Alex. Brown
Incorporated or 0.30% of the entire amount of commissions paid to all brokers
for the Fund. The aggregate amount of transactions involving the payment of
these commissions was $1,339,775, or 0.21% of the entire amount of transactions
effected through all brokers combined for this Fund.

                                 CODE OF ETHICS

         The Gateway Trust and Gateway Investment Advisers L.P. have each
adopted a Code of Ethics which permit employees subject to the codes to invest
in securities, including securities that may be purchased or held by the Gateway
Fund or Gateway Small Cap Index Fund, on a limited basis.

ADDITIONAL TAX MATTERS


         The tax discussion set forth below and in the prospectuses is included
for general information only. Prospective investors should consult their own tax
advisers concerning the tax consequences of an investment in a fund.

FEDERAL TAX MATTERS

         Each of the funds is treated as a separate association taxable as a
corporation. The following information, therefore, applies to each fund
separately unless otherwise specifically stated.

         Each fund has met, and each of the funds in the future intends to meet,
the requirements of the Internal Revenue Code, applicable to regulated
investment companies so as to qualify for the special tax treatment afforded to
such companies. Under Subchapter M of the Code, a regulated investment company
is not subject to federal income tax on the portion of its net investment income
and net realized capital gains which it distributes currently to its
shareholders, provided that certain distribution requirements are met, including
the requirement that at least 90% of the sum of its net investment income and
net short-term capital gains in any fiscal year is so distributed. In addition
to this distribution requirement, one of the principal tests which each fund
must meet in each fiscal year in order to qualify as a regulated investment
company is the "90% Test." The 90% Test requires that at least 90% of a fund's
gross income must be derived from dividends, interest, and gains from the sale
or other disposition of securities, including gains from options.




                                       24
<PAGE>   61

         Gains realized from transactions on put and call options (other than
options on securities indexes) generally will be long term or short term,
depending on the nature of the option transaction and on the length of time the
option is owned by the fund.


         Long-term capital gain distributions (i.e., the excess of any net
long-term capital gains over net short-term capital losses), after utilization
of available capital loss carryforwards, are taxable as long-term capital gains
whether received in cash or additional shares, regardless of how long the
shareholder has held his or her shares, and are not eligible for the
dividends-received deduction for corporations. Distributions of long-term
capital gains which are offset by available loss carryforwards, however, may be
taxable as ordinary income.

         Distributions on shares of any fund received shortly after their
purchase, although substantially in effect a return of capital, are subject to
federal income taxes.

         The tax status of distributions made by each fund during the fiscal
year will be sent to shareholders shortly after the end of such year. Each
prospective investor is advised to consult his or her own tax adviser.
Distributions of net investment income are taxable as ordinary income subject to
allowable exclusions and deductions. Distributions of capital gains are taxable
at either ordinary or long-term capital gains rates, as appropriate, except that
all such gains are normally taxable as ordinary income to the extent they are
offset by capital loss carryforwards.

STATE AND LOCAL TAX ASPECTS

         The laws of several state and local taxing authorities vary with
respect to taxation, and each prospective investor is advised to consult his or
her own tax adviser as to the status of his or her shares and distributions in
respect of those shares under state and local tax laws.

                       TRUSTEES AND OFFICERS OF THE TRUST
                       ----------------------------------

         The Board of Trustees is generally responsible for management of the
business and affairs of the Trust. The Trustees formulate the general policies
of the Trust, approve contracts, and authorize the Trust officers to carry out
the decisions of the Board.

         Under the Trust's Second Amended Agreement and Declaration of Trust, no
annual or regular meetings of shareholders are required. As a result, the
Trustees will continue in office until resignation, retirement, death, or
removal. Trustee vacancies normally are filled by vote of the remaining
Trustees. If at any time less than a majority of the Trustees in office have
been elected by the shareholders, the Trustees must call a shareholder meeting
for the purpose of electing Trustees.

         The Trustees and officers of the Trust, together with information as to
their positions with the Trust and its predecessor, Gateway Option Income Fund,
Inc. (the "Company") and their principal occupations during at least the past
five years, are listed below.


         *WALTER GENE SALL, 400 TechneCenter Drive, Suite 220, Milford, OH
45150; Chairman and Trustee of the Trust; Chairman of the Adviser; various
senior management positions and offices held with the Trust, the Company, and
the Adviser since 1977. Age 55.

         *J. PATRICK ROGERS, 400 TechneCenter Drive, Suite 220, Milford, OH
45150; Trustee of the Trust since December 1998; President of the Trust since
1997; President of the Adviser since 1995; portfolio manager of the Funds since
1997; co-portfolio manager of the Funds from 1995 to 1997; various senior
management positions and offices held with the Trust and the Adviser since 1989.
Age 36.

         JAMES M. ANDERSON, Children's Hospital Medical Center, 3333 Burnet
Avenue, Cincinnati, OH 45229; Trustee of the Trust since April 1997; Children's
Hospital Medical Center, President and Chief Executive Officer since November
1996, Chairman of the Board of Trustees from 1992 through 1996, and Trustee
since 1979; Taft Stettinius & Hollister (law firm), Partner from 1982 to
November 1996; Access Corporation (software distributor), Secretary from 1985 to
1996, Consultant from 1996 to 1997, and Director 1997 to 1998; Cincinnati Stock
Exchange, Trustee since 1978; River City Insurance Limited, Director since 1991.
Age 58.




                                       25
<PAGE>   62


         STEFEN F. BRUECKNER, ProMutual Group, Inc., P. O. Box 9178, Boston, MA
02205; Trustee of the Trust since October 1992; President and Chief Executive
Officer, ProMutual Group (a professional liability insurance company) since
1998; Director, President, and Chief Executive Officer, Anthem Companies, Inc.
(health insurer) 1995 to 1998; Director and President of Community Mutual
Insurance Company (health insurer) from 1991 to 1995, and various management
positions from 1986 to 1991. Age 50.

         KENNETH A. DRUCKER, Sequa Corp., 200 Park Avenue, New York, NY 10166;
Director of the Company from January 1984 to May 1986; Trustee of the Trust
since April 1986; Vice President and Treasurer, Sequa Corporation (gas turbine
and industrial equipment) since November 1987. Age 54.

         BEVERLY J. FERTIG, 8591 Woodbriar Drive, Sarasota, FL 34238; Trustee of
the Trust since September 1988; arbitrator, National Association of Securities
Dealers, Inc., since January 1992; Vice President, Marketing and Communications,
Coffee, Sugar and Cocoa Exchange from January 1989 to December 1991; Executive
Director, National Institutional Options and Futures Society, March 1988 to
December 1988; prior thereto, Vice President, Institutional Marketing, Chicago
Board Options Exchange. Age 69.

         R. S. (DICK) HARRISON, 4040 Mt. Carmel Road, Cincinnati, OH 45244;
Director of the Company from 1977 to 1982; Trustee of the Trust since April
1996; Director/Chairman of the Board, Baldwin Piano & Organ Company from 1994 to
1997; Chairman of the Board/CEO, Baldwin Piano & Organ Company from 1983 to
1994. Prior thereto, various management positions with Baldwin Piano & Organ
Company, Cincinnati, OH. Director of Anderson Bank of Cincinnati, OH and Trustee
of Kenyon College. Age 67.

         WILLIAM HARDING SCHNEEBECK, 251 Indian Harbor Road, Vero Beach, FL
32963; Director of the Company from September 1977 to May 1986; Trustee of the
Trust since April 1986; retired, formerly Chairman of Midwestern Fidelity Corp.
Age 70.

         JAMES E. SCHWAB, XTEK, Inc., 11451 Reading Road, Cincinnati, OH
45241-2283; Trustee of the Trust since December 1998; President of XTEK, Inc. (a
manufacturing company), from November 1995 to present, Vice President of XTEK,
Inc. from October 1994 to November 1995; various executive positions with
American Financial Corporation and its affiliates from 1985 to 1994, including
Senior Vice President of General Cable Corporation from 1992 to 1994 and Senior
Vice President of the Penn Central Corporation (now called the American
Financial Group) from 1989 to 1992. Age 56.

         *GEOFFREY KEENAN, 400 TechneCenter Drive, Suite 220, Milford, OH 45150;
Vice President of the Trust since April 1996; Chief Operating Officer, Gateway
Investment Advisers, L.P. since December 1995; Executive Vice President and
Chief Operating Officer, Gateway Investment Advisers, Inc. since 1995; Vice
President, Gateway Investment Advisers, Inc. from 1991 to 1995. Age 41.

         *PAUL R. STEWART, 400 TechneCenter Drive, Suite 220, Milford, OH 45150;
Treasurer of the Trust since October 1995; Chief Financial Officer of the
Adviser since 1996, Controller of the Adviser from October 1995 to December
1996; Audit Manager and Senior, Price Waterhouse from September 1992 to 1995 and
from August 1988 to August 1991. Age 34.

         *DONNA M. SQUERI, 400 TechneCenter Drive, Suite 220, Milford, OH 45150;
Secretary of the Trust since October 1995; Secretary and General Counsel of the
Adviser since September 1995; in-house counsel of Bartlett & Co., a registered
investment adviser, from October 1984 to September 1993. Age 40.


         *Messrs. Sall, Rogers, Keenan, and Stewart and Ms. Squeri are
affiliated persons of the Trust and the Adviser as defined by the Investment
Company Act of 1940. Mr. Sall and Mr. Rogers are "interested persons" of the
Trust as defined by the Investment Company Act of 1940.

         Messrs. Sall, Rogers, Keenan, and Stewart and Ms. Squeri, each of whom
is employed by the Adviser, receive no remuneration from the Trust. Each Trustee
of the Trust other than Mr. Sall and Mr. Rogers receive fees as follows: (a) an
annual fee of $3,000, payable in equal quarterly installments for services
during each fiscal quarter; (b) a $500 base fee plus $100 per fund for each
regular or special meeting of the Board of Trustees attended; and (c) $200 per
fund ($1,000 per fund for the Chairman) for each Audit Committee meeting
attended. The Trust also reimburses each Trustee for any reasonable and
necessary travel expenses incurred in connection with attendance at such
meetings. In addition, Trustees may receive attendance fees for service on other
committees.



                                       26
<PAGE>   63


         The following table provides information about the compensation
received by each Trustee from the Trust for the year ended December 31, 1999.

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

     NAME OF TRUSTEE            TOTAL COMPENSATION
                                    FROM TRUST
- -------------------------------------------------------
James M. Anderson                   $  4,600
Stefen F. Brueckner                 $  6,200
Kenneth A. Drucker                  $ 12,200
Beverly J. Fertig                   $  6,200
R. S. Harrison                      $  6,600
J. Patrick Rogers                   $      0
Walter G. Sall                      $      0
William H. Schneebeck               $  7,400
James E. Schwab                     $  6,200
- -------------------------------------------------------


SHAREHOLDER MEETINGS AND VOTING

         A meeting of shareholders must be called if shareholders holding at
least 10% of the Trust's shares (or shareholders holding at least 10% of any
fund's shares as to any matter affecting only such fund) file a written request
for a meeting.


         On any matter submitted to a vote of shareholders, shares are voted by
fund, unless an aggregate vote is required by the Investment Company Act of
1940. Shares are voted by fund with respect to the approval or amendment of such
fund's advisory contract. As of April 4 2000, the Adviser held, in a fiduciary
capacity, more than 25% of the outstanding shares of the Small Cap Index Fund.
Thus, the Adviser may be deemed to be a control person of this Fund as of that
date. As of April 4, 2000, DB Alex. Brown LLC held more than 25% of the
outstanding shares of the Gateway Fund. Thus, DB Alex. Brown LLC may be deemed
to be a control person of this Fund as of that date.

         As of April 3, 2000, the shareholders of the Gateway Fund controlled
approximately 95.64% of the outstanding shares of the Trust. Therefore, in the
foreseeable future, when the shareholders of the Trust elect the Trustees or
vote in the aggregate on any other issue, the shareholders of the Gateway Fund
will be able to elect the Trustees or to decide the issue. Shareholders do not
have cumulative voting rights as to the election of Trustees. As a result, if a
shareholder meeting is called to elect Trustees, a majority of the shares voting
at the meeting can elect all of the Trustees.


             INDEPENDENT PUBLIC ACCOUNTANTS AND FINANCIAL STATEMENTS
             -------------------------------------------------------

         Arthur Andersen LLP, 425 Walnut Street, Cincinnati, OH 45202, serves as
independent public accountants of the Trust. Arthur Andersen LLP performs an
annual audit of each fund's financial statements, reviews each fund's tax
returns, and provides financial, tax, and accounting consulting services as
requested.


         The financial statements and independent auditors' report required to
be included in this SAI are incorporated herein by this reference to the Trust's
Annual Report to Shareholders for the fiscal year ended December 31, 1999.


                        PRINCIPAL HOLDERS OF FUND SHARES
                        --------------------------------

GATEWAY FUND



                                       27
<PAGE>   64


         As of April 3, 2000, the Gateway Fund had 47,369,340.149 shares
outstanding. As of such date, each of the following persons or groups was known
by Trust management to be the record and/or beneficial owner (as defined below)
of the indicated amounts of the Fund's outstanding shares.

<TABLE>
<CAPTION>

 --------------------------------------------------------------------------------------------------
                 NAME AND ADDRESS                      NUMBER OF SHARES        PERCENT OF CLASS
 --------------------------------------------------------------------------------------------------
<S>                                                       <C>                    <C>
 DB Alex. Brown LLC Mutual Funds Dept.                    22,284,777                47.04%
 P. O. Box 1346
 Baltimore, MD  21203
 Charles Schwab and Company, Inc.                         8,506,897.               174.96%
 Reinvest Account Special Custody Account for
 Mutual Fund Department
 101 Montgomery Street
 San Francisco, CA  94104
 Trustees and officers of the Trust as a grouop             269,008               Less than 1%
 Advisor officers and directors as a group                   75,854               Less than 1%
 --------------------------------------------------------------------------------------------------
</TABLE>



SMALL CAP INDEX FUND


         As of April 3, 2000, the Small Cap Index Fund had 1,333,594.194 shares
outstanding. As of such date, each of the following persons or groups was known
by Trust management to be the record and/or beneficial owner (as defined below)
of the indicated amounts of the Fund's outstanding shares.
<TABLE>
<CAPTION>

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

             NAME AND ADDRESS OF OWNER                 NUMBER OF SHARES        PERCENT OF CLASS
 --------------------------------------------------------------------------------------------------
<S>                                                        <C>                       <C>
 Andrew Wyeth                                               185,372                   13.90%
 Chadds Ford, PA  19317

 Up East, Inc.                                              183,958                   13.79%
 c/o Betsy J. Wyeth
 P. O. Box 48
 Chadds Ford, PA  19317

 Betsy Wyeth                                                115,224                    8.64%
 Chadds Ford, PA  19317

 Charles Schwab and Company, Inc.                           101,554                    7.62%

 Reinvest Account Special Custody Account for
 Mutual Fund Dept.
 101 Montgomery Street
 San Francisco, CA

 DB Alex. Brown LLC Mutual Funds Dept.                       82,082                    6.87%
 P. O. Box 1346
 Baltimore, MD  21203

 Betsy Wyeth Growth                                          98,222                    7.37%
 Chadds Ford, PA  19317

 Trustees and officers of the Trust as a group               33,937                    2.54%

 Adviser officers and directors as a group                    6,520               Less than 1%
 --------------------------------------------------------------------------------------------------
</TABLE>


         The SEC has defined "beneficial owner" of a security to include any
person who has voting power or investment power with respect to any such
security, any person who shares voting power or investment power with respect to
any such security, or any person who has the right to acquire beneficial
ownership of any such security within 60 days.



                                       28
<PAGE>   65

SHARES HELD BY ADVISER


<TABLE>
<CAPTION>

         As of April 3, 2000, the Adviser held in a fiduciary capacity the
indicated amounts of the outstanding shares of each fund. The Adviser has
investment and voting power over all shares held by it in a fiduciary capacity.

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

       NAME OF FUND            NUMBER OF SHARES       PERCENTAGE OF SHARES
- ------------------------------------------------------------------------------
<S>                                <C>                         <C>
Gateway Fund                       336,974           Less than 1%
Small Cap Index Fund               637,240                    47.78%
- ------------------------------------------------------------------------------
</TABLE>







                                       29
<PAGE>   66

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

                                THE GATEWAY TRUST
- --------------------------------------------------------------------------------








                               CINCINNATI FUND(R)


                       STATEMENT OF ADDITIONAL INFORMATION
                                   MAY 1, 2000








         This Statement is not a prospectus but should be read in conjunction
with the supplement dated May 1, 2000 to the current Prospectus of the
Cincinnati Fund dated May 1, 1999. A copy of the Prospectus and supplement may
be obtained from the Fund by written or telephone request directed to the Fund
at the address or the telephone number shown below.

         The financial statements and independent auditors' report required to
be included in this SAI are incorporated herein by this reference to the annual
and semi-annual reports of the Cincinnati Fund for the fiscal year ended
December 31, 1999 and the year-to-date ended June 30, 1999, respectively.

         The prospectus of the Cincinnati Fund dated May 1, 1999 and supplement
to the prospectus dated May 1, 2000 are also incorporated herein by reference.






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

                                 P. O. BOX 5211
                           CINCINNATI, OHIO 45201-5211
                                 (800) 354-5525


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



<PAGE>   67


                                TABLE OF CONTENTS
                                -----------------

<TABLE>
<CAPTION>

<S>                                                                                            <C>
TABLE OF CONTENTS................................................................................1

INTRODUCTION.....................................................................................2

  General Information About The Gateway Trust....................................................2

INVESTMENT PRACTICES AND RESTRICTIONS............................................................2

  General........................................................................................2

  Investment Restrictions........................................................................3

PERFORMANCE AND RISK INFORMATION.................................................................5

  Performance Information........................................................................5

  Total Return Calculations......................................................................5

      Historical Results.........................................................................6

  Risk Information...............................................................................6

      Comparative Indexes........................................................................6

      Standard Deviation.........................................................................6

      Beta.......................................................................................7

  Rankings And Comparative Performance Information...............................................7

SHAREHOLDER SERVICES.............................................................................7

  Open Account...................................................................................7

  Automatic Investment Program...................................................................7

  IRAs...........................................................................................8

  Systematic Withdrawal Program..................................................................9

ADDITIONAL PURCHASE AND REDEMPTION INFORMATION...................................................9

INVESTMENT ADVISORY AND OTHER SERVICES..........................................................10

  Gateway Investment Advisers, L.P..............................................................10

  Investment Advisory Contract..................................................................11

  Custodian.....................................................................................12

  Shareholder Servicing, Transfer, Dividend Disbursing, And Financial Servicing Agent...........13

BROKERAGE.......................................................................................13

  Additional Tax Matters........................................................................14

  Federal Tax Matters...........................................................................14

  State And Local Tax Aspects...................................................................15

CODE OF ETHICS..................................................................................15

TRUSTEES AND OFFICERS OF THE TRUST..............................................................15

  Shareholder Meetings And Voting...............................................................17

INDEPENDENT PUBLIC ACCOUNTANTS AND FINANCIAL STATEMENTS.........................................17

PRINCIPAL HOLDERS OF CINCINNATI FUND SHARES.....................................................17

SCHEDULE A......................................................................................18
</TABLE>



<PAGE>   68



                                  INTRODUCTION

GENERAL INFORMATION ABOUT THE GATEWAY TRUST

         The Gateway Trust (the "Trust") is an Ohio business trust which is
authorized to establish and operate one or more separate series of mutual funds
(herein referred to as "funds" or individually as a "fund"). Each fund has its
own investment policies, restrictions, practices, assets, and liabilities. Each
fund is represented by a separate series of shares of beneficial interest in the
Trust ("Shares"). The Trust's operation is governed by Chapter 1746 of the Ohio
Revised Code, by a Second Amended Agreement and Declaration of Trust dated as of
December 29, 1992, as amended, and by the Trust's bylaws, as amended.

         At present, there are three series of the Trust:
<TABLE>
<CAPTION>

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

                         NAME OF FUND                     DATE ORGANIZED                      FORMER NAMES
           ----------------------------------------------------------------------------------------------------------------
<S>                                                     <C>                    <C>
           Gateway Fund                                 1977                    Gateway Index Plus Fund until April 30,
                                                                                1998; Gateway Option Index Fund until
                                                                                March 1990; Gateway Option Income Fund
                                                                                until February 1988; Gateway Option
                                                                                Income Fund, Inc. until May 1986
           Gateway Small Cap Index Fund                 April 1993              None
           Cincinnati Fund(R)                           November 1994           None
           ----------------------------------------------------------------------------------------------------------------
</TABLE>

         Gateway Option Income Fund, Inc., the predecessor to the Trust, was
organized in 1977 as a Maryland corporation. It was reorganized to become the
Trust effective as of May 2, 1986, with the Gateway Option Income Fund as its
sole initial fund. As a result of the transaction, shareholders of the
corporation on May 2, 1986, became shareholders of the Option Income Fund.

         The Gateway Fund and the Gateway Small Cap Index Fund are offered in
two separate prospectuses (the "Prospectuses"). The Cincinnati Fund is offered
in a separate prospectus (the "Cincinnati Prospectus"). The Cincinnati Fund has
a separate Statement of Additional Information. The other two funds have a
combined Statement of Additional Information.

         Gateway Investment Advisers, L.P. (the "Adviser") acts as the funds'
investment adviser.


                      INVESTMENT PRACTICES AND RESTRICTIONS
                      -------------------------------------

GENERAL

         The investment objective of the Cincinnati Fund (the "Fund") is to
achieve capital appreciation through investment in the common stock of companies
with an important presence in the Greater Cincinnati Area ("Cincinnati
Companies"). The Cincinnati Fund is a diversified, open-end management
investment company.


         Investment Practices: The Fund attempts to achieve its objective by
investing in the common stocks of Cincinnati Companies that meet certain
criteria included in a proprietary model developed by the Adviser. These
criteria include level of employment and nature of operations in the Greater
Cincinnati Area. The Adviser has also incorporated certain industry
diversification, liquidity, market capitalization, and listing criteria into the
model. The Adviser uses the proprietary model to select the Fund's portfolio of
stocks and to determine the proportion of the Fund's assets that are invested in
each stock.




                                       2
<PAGE>   69



         To be eligible for inclusion in the Fund's portfolio, a stock currently
must meet the following model criteria: (1) the stock must be issued either by a
company that employs at least fifty persons in the Greater Cincinnati Area or by
a company that maintains its corporate headquarters in the Greater Cincinnati
Area; (2) the stock must be issued by a company with a market capitalization of
$5 million or more; and, (3) the stock must be listed on a national securities
exchange, such as the New York Stock Exchange, the American Stock Exchange, or
the National Market System of the NASDAQ. The Greater Cincinnati Area, for
purposes of the model, is defined as the Cincinnati and Hamilton-Middletown
Consolidated Metropolitan Statistical Area (the "CMSA"). The CMSA includes
Hamilton, Clermont, Warren, and Butler counties in Ohio; Boone, Campbell, and
Kenton counties in Kentucky; and Dearborn County in Indiana.


         The Adviser rebalances the portfolio and makes appropriate adjustments
in the portfolio to reflect changes in the underlying corporate data. In
addition, the Adviser may modify the proprietary model, or the selection
criteria incorporated in the model, in response to market and economic
developments. Such modifications could result in changes to the composition of
the Fund's portfolio.

         The Cincinnati Fund may hold cash for purposes of liquidity or for
temporary defensive purposes. The Fund generally will hold cash reserves for the
purpose of paying expenses and share redemptions and may hold cash received from
the sale of the Fund's shares which has not yet been invested. In addition, the
Adviser may determine from time to time that, for temporary defensive purposes,
the Fund should reduce (and in periods of unusual market conditions reduce
substantially or liquidate entirely) its investment in common stock. For
temporary defensive purposes, the Fund may hold up to 100% of its assets in
cash.

         Cash is normally invested in repurchase agreements. Cash may also be
invested in securities of the U. S. government or any of its agencies, bankers'
acceptances, commercial paper, or certificates of deposit (collectively "cash
instruments"). Commercial paper investments will be limited to investment grade
issues rated A-1 or A-2 by Standard & Poor's or Prime-1 or Prime-2 by Moody's
Investors Service, Inc. Certificates of deposit investments will be limited to
obligations of domestic banks with assets of $1 billion or more. Under normal
conditions, the Adviser does not intend to invest more than 5% of the Fund's net
assets in any cash instruments other than repurchase agreements.

         Repurchase agreements are instruments under which the Fund buys
securities suitable for investment under its policies and obtains the concurrent
agreement of the seller (usually a bank) to repurchase such securities at an
agreed-upon date, price, and interest rate. Investments in repurchase agreements
are subject to the risk that the selling bank may default in its repurchase
obligation. However, not more than 5% of the Fund's total assets may be invested
in repurchase agreements which have a maturity longer than seven days.

INVESTMENT RESTRICTIONS

         The Trust has adopted certain fundamental policies with respect to the
Fund that may not be changed without a vote of shareholders of the Fund. Under
these policies, the Fund may not:

         1.     purchase any security if, as a result, the Fund (or the funds in
                the Trust together) would then hold more than 10% of any class
                of securities of an issuer (taking all common stock issues of an
                issuer as a single class, all preferred stock issues as a single
                class, and all debt issues as a single class), or more than 10%
                of the outstanding voting securities of an issuer.

         2.     purchase any security if, as a result, the Fund would then have
                more than 5% of its total assets (taken at current value)
                invested in securities of companies (including predecessors)
                less than three years old and in equity securities for which
                market quotations are not readily available.

         3.     purchase  securities on margin (but the Fund may obtain such
                short-term  credits as may be necessary for the clearance of
                purchase and sales of securities).

         4.     make short sales of securities or maintain a short position (a)
                unless, at all times when a short position is open, the Fund
                owns an equal amount of such securities or securities
                convertible into or exchangeable (without payment of any further
                consideration) for securities of the same issue as, and equal in
                amount to, the securities sold short, and



                                       3
<PAGE>   70

                (b) unless not more than 10% of the Fund's net assets (taken
                at current value) are held as collateral for such sales at any
                one time.

                It is the present intention of management to make such sales
                only for the purpose of deferring realization of gain or loss
                for federal income tax purposes.

         5.     borrow money except as a temporary measure for extraordinary or
                emergency purposes and then only from banks and only in amounts
                not in excess of 5% of the Fund's total assets (except to meet
                redemption requests as discussed below), taken at the lower of
                cost or market.

                It is the present intention of management that the Fund will not
                purchase additional portfolio securities at any time when its
                borrowing exceeds 5% of its total assets. In order to meet
                redemption requests without immediately selling any portfolio
                securities, the Fund may borrow an amount up to 25% of the value
                of its total assets including the amount borrowed. If, due to
                market fluctuations or other reasons, the value of the Fund's
                assets falls below 400% of its borrowing, the Fund will reduce
                its borrowing which may result in the Fund being required to
                sell securities at a time when it may otherwise be
                disadvantageous to do so. This borrowing is not for investment
                leverage but solely to facilitate management of the portfolio by
                enabling the Fund to meet redemption requests where the
                liquidation of portfolio securities is deemed to be inconvenient
                or disadvantageous. However, the Fund might be deemed to be
                engaged in leveraging in that any such borrowing will enable the
                Fund to continue to earn money on investments which otherwise
                may have been sold in order to meet redemption requests.

         6.     pledge more than 10% of its total assets, taken at market value.

         7.     purchase or retain securities of any company if, to the
                knowledge of the Trust, officers and trustees of the Trust or of
                the Adviser who individually own more than 1/2 of 1% of the
                securities of that company together own beneficially more than
                5% of such securities.

         8.     buy or sell commodities or commodities futures or options
                contracts, or real estate or interests in real estate, although
                it may purchase and sell (a) securities which are secured by
                real estate, and (b) securities of companies which invest or
                deal in real estate.

         9.     act as underwriter except to the extent that, in connection
                with the disposition of portfolio securities, it may be deemed
                to be an underwriter under certain provisions of the federal
                securities laws.

         10.    make investments for the purpose of exercising control or
                management.

         11.    participate on a joint or joint and several basis in any trading
                account in securities.

         12.    purchase any security restricted as to disposition under the
                federal securities laws.

         13.    invest in securities of other investment companies, except as
                part of a merger, consolidation, or other acquisition.

         14.    invest in interests in oil, gas, or other mineral exploration or
                development programs, although it may invest in the common
                stocks of companies which invest in or sponsor such programs.

         15.    make loans, except through the purchase of bonds, debentures,
                commercial paper, corporate notes, and similar evidences of
                indebtedness of a type commonly sold privately to financial
                institutions (subject to the limitation in paragraph 12 above),
                and except through repurchase agreements.

                No more than 5% of the Fund's assets will be invested in
                repurchase agreements which have a maturity longer than seven
                days. In addition, the Fund will not enter into repurchase



                                       4
<PAGE>   71


                agreements with a securities dealer if such transactions
                constitute the purchase of an interest in such dealer under the
                Investment Company Act of 1940. The purchase of a portion of an
                issue of such securities distributed publicly, whether or not
                such purchase is made on the original issuance, is not
                considered the making of a loan.

         16.    purchase any security (other than U. S. government
                obligations) if, as a result thereof, less than 75% of the
                value of the Fund's total assets is represented by cash and
                cash items (including receivables), government securities, and
                other securities which, for purposes of this calculation, are
                limited in respect of any one issuer to an amount not greater
                in value than 5% of the value of the Fund's total assets and
                to not more than 10% of the outstanding voting securities of
                such issuer.

         All of the funds in the Trust taken as a group also must satisfy this
10% test.

         17.    concentrate the investments of the Fund in a single industry.

         18.    write, purchase, or sell puts, calls, or combinations thereof.

         19.    buy or sell commodities, commodities futures contracts, or
                commodities options contracts.

         The Trust has no fundamental policy with respect to the issuance of
senior securities by the Fund; however, the Investment Company Act of 1940
prohibits the Trust's issuance of any such securities.

         In addition to these fundamental policies, the Fund will not purchase
additional portfolio securities while borrowings in excess of 5% of the Fund's
total assets are outstanding. The Adviser has no current intention of causing
the Fund to borrow in excess of 5% of the Fund's total assets in the coming
year.


                        PERFORMANCE AND RISK INFORMATION
                        --------------------------------

PERFORMANCE INFORMATION

         The Fund may quote performance in various ways. All performance
information supplied by the Fund is based upon historical results and is not
intended to indicate future performance. Total returns and other performance
information may be shown numerically or in a table, graph, or similar
illustration. The Fund's share prices and total returns fluctuate in response to
market conditions, interest rates, and other factors.

TOTAL RETURN CALCULATIONS

         Total returns reflect all aspects of a fund's return, including the
effect of reinvesting dividends and capital gains distributions, and any change
in a fund's net asset value per share (the "NAV") over the period. Average
annual total returns are calculated by determining the average annual compounded
rates of return over one-, five-, and ten-year periods that would equate an
initial hypothetical investment to the ending redeemable value calculated
according to the following formula:

   P (1 + T) to the nth power = ERV where  T   = Average annual total return
                                           N   = Number of years and portion of
                                                 a year
                                           ERV = Ending redeemable value (of an
                                                 initial hypothetical $1,000
                                                 investment) at the end of the
                                                 period
                                           P   = $1,000 (the hypothetical
                                                 initial investment)

         If a fund has been in existence for less than one, five, or ten years,
the time period since the date it commenced operations will be substituted for
the periods stated.

         As a hypothetical example, a cumulative return of 100% growth on a
compounded basis in ten years would produce an average annual total return of
7.18%, which is the annual rate that would equal 100% growth on a compounded
basis in ten years. While average annual total returns are convenient means of
comparing investment alternatives, investors should realize that a fund's
performance is not constant over time, but changes from year to



                                       5
<PAGE>   72

year, and that average annual total returns represent averaged figures as
opposed to the actual year-to-year performance of the fund.

         Average annual total return is calculated as required by applicable
regulations promulgated by the Securities and Exchange Commission (the "SEC").
In addition to average annual total returns, the Fund may quote year-by-year
total returns and cumulative total returns reflecting the simple change in value
of any investment over a stated period. Average annual, year-by-year, and
cumulative total returns may be quoted as a percentage or as a dollar amount.


<TABLE>
<CAPTION>

         HISTORICAL RESULTS
         The following table shows the Fund's average annual and cumulative
total returns for the period ended December 31, 1999:

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

                                             ONE YEAR        FIVE YEARS         LIFE OF FUND
- -------------------------------------------------------------------------------------------------
<S>                                          <C>                <C>              <C>
Average Annual Total Return                   -4.13%              17.57%           16.82%
Cumulative Total Return                       -4.13%             124.63%          122.61%
- -------------------------------------------------------------------------------------------------
</TABLE>

         The table below shows the redeemable value on December 31, 1999, for an
initial investment of $10,000 in the Fund that was made at the beginning on the
one- and five-year periods, and the commencement of the Fund's operations. The
table assumes all dividends and distributions have been reinvested in additional
shares.

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

       ONE YEAR            FIVE YEARS         LIFE OF FUND
- ---------------------------------------------------------------
        $9,587              $22,463             $22,261
- ---------------------------------------------------------------

RISK INFORMATION

         In evaluating the performance of any investment including the Fund, it
is important to understand the risks involved in the investment. Information
regarding the performance of an investment, while valuable in itself, is more
meaningful when it is related to the level of risk associated with that
investment. Thus, two different mutual funds that produce similar average annual
total returns may present markedly different investment opportunities if the
risk of loss associated with one mutual fund is greater than that of the other
mutual fund.

         For example, an investment in a mutual fund that invests in stocks
generally will present greater potential for variation in the share price of the
mutual fund, and hence a greater risk of gain or loss than an investment in a
mutual fund that invests in short-term U. S. government securities. Because the
potential for greater gain typically carries with it a greater degree of risk,
the advisability of an investment in a particular mutual fund for a given
investor will depend not only on historical performance of the fund but also on
the potential for gain and loss associated with that mutual fund.

         The Gateway Trust offers three different funds that produce different
total returns and present different risk potentials. The difference in risk
potential can be demonstrated by various statistical concepts. The following
statistical concepts can be used to measure some of the risks associated with an
investment in the Fund.

         COMPARATIVE INDEXES
         The performance and risk of the Fund may be compared to various broadly
recognized indexes such as the S&P 500 Index or the Lehman Government/Corporate
Bond Index. These comparative indexes are used because they are the standard
benchmarks of the stock market and bond market respectively. The Fund's
performance and risk may also be compared to other appropriate indexes.

         STANDARD DEVIATION
         Standard deviation measures the volatility of the total return of the
Fund. Standard deviation is one method of comparing the total return of a fund
to the average monthly total return of the Fund. In general, a fund that has a
greater standard deviation is a fund that has displayed a greater tendency to
vary from its own average monthly total return. Standard deviation can also be
used to compare the total return of a fund to the total return of an index or
another mutual fund. By comparing the magnitude of the standard deviation of
each investment, an analyst is able



                                       6
<PAGE>   73

to determine the relative volatility of each investment. An investment with an
expected return of 10% and a standard deviation of 15% would be expected to earn
a total return ranging from -5% to +25% about 68% of the time, a total return
ranging from -20% to +40% about 95% of the time, and a total return ranging from
- -35% to +55% about 97% of the time.

         BETA
         Beta analyzes the market risk of the Fund by showing how responsive the
Fund is to the market as defined by an index. Beta is a comparative measure of
the Fund's volatility in relation to an appropriate index. Generally, higher
betas represent riskier investments. By definition, the beta of the market is
1.00. Thus, a fund with a beta higher than 1.00 is expected to perform better
than the market in up markets and worse than the market in down markets. Beta is
the slope of the "least square line" which compares the Fund with an index.

RANKINGS AND COMPARATIVE PERFORMANCE INFORMATION

         The Fund may compare its performance to that of other mutual funds or
categories of mutual funds as reported by independent services such as
Morningstar, Inc., Lipper Analytical Services, Inc., and Value Line Mutual Fund
Survey, or by other financial publications with a circulation of 10,000 readers
or more.

         Performance comparisons may be expressed as ratings, such as the
proprietary ratings published by Morningstar, Inc., or rankings, such as the
rankings of funds in various categories published by Lipper Analytical Services,
Inc. Performance comparisons may also be expressed as designations (such as a
certain number of "stars") or descriptions (such as "best fund") assigned by
such services or publications.


                              SHAREHOLDER SERVICES
                              --------------------

         Gateway Investment Advisers, L.P. serves as the Trust's shareholder
servicing, transfer, dividend disbursing, and financial servicing agent (the
"Servicing Agent"). In this capacity, it performs various shareholder services
on behalf of the Trust.

OPEN ACCOUNT

         The Fund's regular account for investors who purchase its shares is the
Open Account. The Open Account facilitates regular purchases of Fund shares over
a period of years and provides the option of receiving dividends and
distributions either in cash or in Fund shares. Gateway does not charge for the
automatic reinvestment of dividends and distributions.

         The Servicing Agent maintains a record of the investor's purchases,
redemptions, and share balances in the investor's Open Account. Shortly after
each purchase, the Servicing Agent will mail a confirmation to the investor
showing the shares purchased, the exact price paid for the shares, and the total
number of shares owned. Share certificates will not be issued.

         Upon opening an account, the investor may elect either of the following
options: (1) reinvestment at net asset value of all distributions, or (2)
payment in cash of all distributions. If no election is made, all distributions
will be reinvested at net asset value. An election may be changed by a letter or
telephone call to the Servicing Agent. No annual maintenance fees are charged by
the Trust on any Open Account. The Trust reserves the right to charge annual
fees in the future. Shareholders will be notified of any change in the annual
fee arrangement.

AUTOMATIC INVESTMENT PROGRAM

         Investors can arrange to use our Automatic Investment Program by either
making the election on the New Account Application or by contacting Shareholder
Services at (800) 354-6339 for the appropriate forms. With this service,
investors purchase additional shares by having a predetermined amount of $100 or
more automatically transferred from a bank account to the Trust on a monthly or
quarterly basis. Changes to an Automatic Investment Program, including
discontinuing participation, must be in writing and sent to The Gateway Trust,
Shareholder Services, P. O. Box 5211, Cincinnati, OH 45201-5211. All changes to
the Program must be received by Gateway at least five business days prior to the
next scheduled transfer.



                                       7
<PAGE>   74

IRAS

         Investors may purchase shares of the Fund through Individual Retirement
Accounts ("IRAs") which are permitted to invest in shares of a mutual fund. The
Trust itself sponsors a traditional IRA (the "Gateway Traditional IRA") and a
Roth IRA (the "Gateway Roth IRA") or jointly as a "Gateway IRA". A Gateway IRA
can be adopted by an investor and is specifically designed to permit the
investor to invest in shares of any Gateway fund selected by the investor. The
custodian of the Gateway IRA is Firstar Bank, N.A.. Investors can obtain forms
to establish a Gateway IRA by calling Shareholder Services at (800) 354-5525.

         An IRA is a special program with certain tax benefits that generally
permits an investor to establish and contribute to his or her own retirement
plan. For detailed information about a Gateway IRA, please refer to the
Agreement and Disclosure Statement for the appropriate Gateway IRA. Agreements
and Disclosure Statements can be obtained by calling Shareholder Services at
(800) 354-5525.

         An investor may make a direct transfer of assets from one IRA to a
Gateway IRA by directing the existing IRA custodian or trustee to transfer
directly to the Gateway IRA the amount held in that prior IRA, without directly
receiving those funds or being taxed on the transfer. There is no minimum
holding period for a direct transfer of IRA assets from one custodian or trustee
to another. Call Shareholder Services at (800) 354-5525 to obtain the
appropriate transfer form.

         A Gateway Traditional IRA is eligible to receive direct rollovers of
distributions from a qualified employer plan. An investor can make a direct
rollover by instructing the employer's plan to wire the distribution to Firstar
Bank, N.A. as custodian for a Gateway Traditional IRA. The distribution should
be wired to:

                  The Gateway Trust c/o Firstar Bank, N.A.
                  ABA #042-0000-13
                  Cincinnati, OH
                  Name (insert investor name)
                  Gateway Account No. (insert investor account number)
                  Name of Gateway fund(s) in which you wish to invest.

         An investor can also make a direct rollover to a Gateway Traditional
IRA by instructing the employer's plan to prepare a check for the amount to be
rolled over payable to "Firstar Bank, N.A., as Custodian of Individual
Retirement Account of (insert investor name)," and sending that check to
Gateway. The check can also be delivered in person to Gateway, or mailed to:

                  The Gateway Trust
                  Shareholder Services
                  P. O. Box 5211
                  Cincinnati, OH 45201-5211

         An investor can make a 60-day rollover of a distribution from a
qualified employer plan by instructing the employer's plan to prepare a check
payable to the investor and by endorsing or cashing the check and depositing
some or all of the proceeds in a Gateway Traditional IRA. The deposit must be
delivered in person to Gateway, or mailed to The Gateway Trust at the above
address within 60 days of when the investor receives the distribution. The
employer's plan must withhold 20% of the taxable amount for federal income tax
if the investor chooses a 60-day rollover for the distribution.

         Some portions of distributions from other IRAs or from tax-qualified
profit sharing, stock bonus, pension, or annuity plans are not eligible for
regular or direct rollovers. For instance, distributions of nontaxable after-tax
employee contributions or required minimum payments made after an individual
reaches age 70 1/2 cannot be rolled over.

         To make a withdrawal from a Gateway IRA, an investor should contact
Shareholder Services at (800) 354-5525.

         The rules for contributing to, investing under, and distributing from
IRAs are complex, and any investor should consult with his or her own tax
adviser if he or she has any questions with respect to IRAs and to determine if
there have been any recent changes to the rules. At the time an IRA is
established, the custodian or trustee of the



                                       8
<PAGE>   75

IRA is required by law to provide a disclosure statement to the individual
setting forth important information concerning IRAs.

         Further information concerning IRAs can be obtained from any district
office of the Internal Revenue Service. In particular, Publication 590 of the
Internal Revenue Service provides general information as to IRAs.

         No annual maintenance fees are charged by the Trust for any account,
including IRAs, SEP-IRAs, retirement, and pension or profit-sharing plans,
including 401(k) plans. The Trust reserves the right to charge annual fees in
the future. Shareholders will be notified of any change in the annual fee
arrangement.

SYSTEMATIC WITHDRAWAL PROGRAM

         If the value of a shareholder's account is at least $5,000, the
shareholder can request withdrawals on either a monthly or a quarterly basis in
the minimum amount of $100. The Trust makes no recommendation as to the minimum
amount to be periodically withdrawn by a shareholder. A sufficient number of
shares in the shareholder's account will be sold periodically (normally one
business day prior to each withdrawal payment date) to meet the requested
withdrawal payments.

         If a shareholder participates in the Systematic Withdrawal Program, all
dividends and distributions on shares held in the account will be reinvested in
additional shares at net asset value. Since the withdrawal payments represent
the proceeds from sales of fund shares, there will be a reduction, and there
could even be an eventual depletion, of the amount invested in the Fund to the
extent that withdrawal payments exceed the dividends and distributions paid and
reinvested in shares. Withdrawals under the Systematic Withdrawal Program should
not, therefore, be considered a yield on investment. A shareholder can make
arrangements to use the Systematic Withdrawal Program (or discontinue
participation) by contacting Shareholder Services at (800) 354-5525.


                 ADDITIONAL PURCHASE AND REDEMPTION INFORMATION
                 ----------------------------------------------

         Shares of the Fund are purchased and redeemed at their net asset value
as next determined following receipt of the purchase order or redemption notice.
Redemptions under the Systematic Withdrawal Program and installment
distributions from IRAs are effected at the net asset value next determined on
or after the date designated for the redemption or distribution. Information as
to the method of calculating the net asset value of shares of the Fund is
included in the Cincinnati Prospectus under the caption "How Fund Shares Are
Priced."

         Certificates for shares of the Fund will not be issued.

         The minimum initial investment is $1,000 ($500 for IRAs). The minimum
additional investment is $100, subject to certain exceptions such as investments
by the Adviser's employees, by participants in an SEP-IRA program, and by
participants in the Automatic Investment Program. The Trust reserves the right
to reject any purchase order of the Fund.

         There is no minimum or maximum applicable to redemption of shares of
the Fund. The Trust, however, reserves the right to redeem a shareholder's
account(s) under certain circumstances. The shareholder will receive at least 60
days' written notice prior to the redemption of the account(s).

         The Trust may redeem a shareholder's account(s) in the Fund when the
aggregate value of the shareholder's account(s) falls below $800 (other than as
a result of market action). The shareholder may prevent such redemption by
increasing the value of the account(s) to $1,000 or more within the 60-day
period.

         The Trust will redeem a shareholder's account if the shareholder does
not provide a valid U. S. social security number or taxpayer identification
number or other requested documents. The shareholder may prevent such redemption
by providing the requested information within the 60-day period.

         The Trust reserves the right to terminate temporarily or permanently
the exchange privilege for any shareholder who makes an excessive number of
exchanges between funds. The shareholder will receive written notice that the
Trust intends to limit the shareholder's use of the exchange privilege.
Generally the Trust limits a shareholder to twelve exchange transactions per
calendar year. Accounts under common ownership or control,



                                       9
<PAGE>   76

including accounts with the same taxpayer identification number, normally will
be counted as one account for purposes of the exchange limit.

         The Trust also reserves the right to terminate or modify the exchange
privilege or to refuse an exchange if the exchange would adversely affect a fund
involved in the exchange.

         Signature guarantees are required for all redemptions (on the date of
receipt by the Servicing Agent of all necessary documents), regardless of the
amount involved, when the proceeds are to be paid to someone other than the
registered owner(s). The signature guarantee requirement may be waived by the
Trust in certain instances. The Trust also reserves the right to require a
signature guarantee on any instructions or redemptions given to the Trust for
any reason. The purpose of signature guarantees is to prevent fraudulent
redemptions which could result in losses to the Trust, the Servicing Agent, or
shareholders. A signature guarantee will be accepted from banks, brokers,
dealers, municipal securities dealers or brokers, government securities dealers
or brokers, credit unions (if authorized by state law), national securities
exchanges, registered securities associations, clearing agencies, and savings
associations. Notary publics are unacceptable guarantors. The signature
guarantees must appear either (a) on the written request for redemption; (b) on
a stock power which should specify the total number of shares to be redeemed; or
(c) on all stock certificates tendered for redemption.

         The right of redemption may be suspended or the date of payment
postponed (a) for any periods during which the New York Stock Exchange is closed
(other than for customary weekend and holiday closings); (b) when trading in any
of the markets which the Fund normally utilizes is restricted as determined by
the SEC; (c) if any emergency exists as defined by the SEC so that disposal of
investments or determination of the Fund's net asset value is not reasonably
practicable; or (d) for such other periods as the SEC by order may permit for
protection of the Trust's shareholders.

         The Trust has elected to be governed by Rule 18f-1 of the Investment
Company Act which obligates the Fund to redeem shares in cash with respect to
any one shareholder during any 90-day period up to the lesser of $250,000 or 1%
of the assets of the Fund. Although payment for redeemed shares generally will
be made in cash, under abnormal circumstances the Board of Trustees of the Trust
may determine to make payment in securities owned by the Fund. In such event,
the securities will be selected in such manner as the Board of Trustees deems
fair and equitable, in which case brokerage and other costs may be incurred by
such redeeming shareholders in the sale or disposition of their securities. To
date, all redemptions have been made in cash.

         The Trust reserves the right to modify or terminate any purchase,
redemption, or other shareholder service procedure upon written notice to
shareholders.

         Purchases and redemptions generally may be effected only on days when
the stock exchanges are open for trading. These exchanges are closed on
Saturdays and Sundays and the following holidays: New Year's Day, Martin Luther
King Jr. Day, Presidents' Day, Good Friday, Memorial Day, Independence Day,
Labor Day, Thanksgiving, and Christmas Day.


                     INVESTMENT ADVISORY AND OTHER SERVICES
                     --------------------------------------

GATEWAY INVESTMENT ADVISERS, L.P.


         Gateway Investment Advisers, L.P. (the "Adviser"), a Delaware limited
partnership, has acted as the investment adviser for the Fund since December 15,
1995. Gateway Investment Advisers, Inc. ("GIA") provided investment advisory
services to the Fund from its formation until December 15, 1995. The Adviser
became the successor in interest to the assets, business, and personnel of GIA
which was organized in June 1977. GIA is the general partner of the Adviser with
a 76% ownership interest, while Alex. Brown Investments Incorporated ("ABII") is
a limited partner with a 15% ownership interest. ABII is an affiliate of DB
Alex. Brown LLC, a nationally known investment banking firm and registered
broker/dealer located in Baltimore, Maryland. Walter G. Sall, Chairman and a
Trustee of the Trust, and J. Patrick Rogers, the portfolio manager of the Funds
and President and a Trustee of the Trust, together own of record and
beneficially 99.85% of the outstanding shares of GIA and thereby control the
Adviser. Mr. Sall is Chairman and a director of GIA and Mr. Rogers is its
President and a director. The third director of GIA is Margaret-Mary V. Preston
who is employed by DB Alex. Brown LLC as a Managing Director.





                                       10
<PAGE>   77

INVESTMENT ADVISORY CONTRACT

         The Trust has retained the Adviser under an investment advisory
contract ("Adviser Contract") to act as investment manager and in such capacity
supervise the investments of the Fund, subject to the policies and control of
the Trust's Board of Trustees. The Adviser Contract for the Fund became
effective on December 15, 1995. Services were provided by GIA under a
substantially identical contract prior to this date.

         Pursuant to the Adviser Contract, the Adviser, at its sole expense,
provides the Fund with (i) investment recommendations regarding the Fund's
investments; (ii) office space, telephones, and other office equipment; and
(iii) clerical and secretarial staff and the services, without additional
compensation, of all officers of the Trust. In addition, the Adviser has agreed
to bear (i) advertising and other marketing expenses in connection with the sale
of the shares of the Fund; (ii) expenses of printing and distributing the Fund's
prospectus and related documents to prospective shareholders; and (iii)
association membership dues (other than for the Investment Company Institute).
The Adviser Contract further provides that under certain circumstances the
Adviser may cause the Fund to pay brokerage commissions in order to enable the
Adviser to obtain brokerage and research services for its use in advising the
Fund and the Adviser's other clients, provided that the amount of commission is
determined by the Adviser, in good faith and in the best interests of the Fund,
to be reasonable in relation to the value of the brokerage and research services
provided.

         The Adviser Contract provides that all expenses not specifically
assumed by the Adviser which may be incurred in the operation of the Trust and
the offering of its shares will be borne by the Trust. Such expenses will be
allocated among the funds in the Trust by direction of the Board of Trustees,
most frequently on the basis of expenses incurred by each fund, but where that
is not practicable on such basis as the Trustees determine to be appropriate.
Expenses to be borne by the Trust include:

     -   fees and expenses of trustees not employed by the Adviser;
     -   expenses of printing and distributing prospectuses to current
         shareholders of the Trust;
     -   expenses pertaining to registering or qualifying the Trust or its
         shares under various federal and state laws, and maintaining and
         updating such registrations and qualifications;
     -   interest expense, taxes, fees, and commissions (including brokerage
         commissions) of every kind;
     -   expenses related to repurchases and redemptions of shares;
     -   charges and expenses of custodians, transfer agents, dividend
         disbursing agents, and registrars;
     -   expenses of valuing shares of each fund;
     -   printing and mailing costs other than those expressly assumed by the
         Adviser;
     -   auditing, accounting, and legal expenses;
     -   expenses incurred in connection with the preparation of reports to
         shareholders and governmental agencies;
     -   expenses of shareholder meetings and proxy solicitations;
     -   insurance expenses;
     -   all "extraordinary expenses" which may arise, including all losses and
         liabilities incurred in connection with litigation proceedings and
         claims, and the legal obligations of the Trust to indemnify its
         officers, trustees, and agents with respect thereto.

         A majority of the Board of Trustees of the Trust and a majority of the
trustees who are not "interested persons" (as defined in the Investment Company
Act of 1940) of any party to the Adviser Contract of the Fund, voting
separately, shall determine which expenses shall be characterized as
"extraordinary expenses."

         In return for the services and facilities furnished by the Adviser
under the Adviser Contract, the Fund pays the Adviser an advisory fee ("the
Advisory Fee") computed at an annual rate of 0.50% of the average daily net
asset value of the Fund.

         If total expenses of the Fund for any fiscal year (including the
Adviser's compensation, but exclusive of taxes, interest, brokerage commissions,
and any "extraordinary expenses" determined as described above) exceed 2.00% of
the Fund's average daily net asset value for such year, the Adviser Contract
requires the Adviser to bear all such excess expenses up to the amount of the
Advisory Fee. Each month the Advisory Fee is determined and the Fund's expenses
are projected. If the Fund's projected expenses are in excess of the
above-stated expense limitation, the Advisory Fee paid to the Adviser will be
reduced by the amount of the excess expenses, subject to an annual adjustment;
provided, however, that the aggregate annual reduction from the Adviser to the
Fund shall not exceed the aggregate Advisory Fee paid by the Fund to the Adviser
for such year.




                                       11
<PAGE>   78

         The Adviser Contract further provides that in the absence of willful
misfeasance, bad faith, gross negligence, or reckless disregard of its duties or
obligations thereunder, the Adviser is not liable to the Trust or any of its
shareholders for any act or omission by the Adviser. The Adviser Contract
contemplates that the Adviser may act as an investment manager or adviser for
others.

         The Adviser Contract may be amended at any time by the mutual consent
of the parties thereto, provided that such consent on the part of the Trust
shall have been approved by the vote of a majority of the Trust's Board of
Trustees, including the vote cast in person by a majority of the trustees who
are not "interested persons" (as defined in the Investment Company Act of 1940)
of any party to the Adviser Contract, and by vote of the shareholders of the
Fund.

         The Adviser Contract may be terminated, upon 60 days' written notice
(which notice may be waived) at any time without penalty (i) by the Board of
Trustees of the Trust; (ii) by the vote of a majority of the outstanding voting
securities of the Fund; or (iii) by the Adviser. The Adviser Contract terminates
automatically in the event of its assignment (as that term is defined in the
Investment Company Act of 1940) by the Adviser.


         The Adviser Contract continues in effect until December 31, 2000, and
thereafter, provided that its continuance for the Fund for each renewal year is
specifically approved in advance (i) by the Board of Trustees of the Trust or by
vote of a majority of the outstanding voting securities of the Fund, and (ii) by
vote of a majority of the trustees who are not parties to the Adviser Contract
or "interested persons" of any party to the Adviser Contract (other than as
Trustees of the Trust), by votes cast in person at a meeting specifically called
for such purpose.

         The following table shows the Advisory Fees earned by the Adviser (or
GIA) for providing services to the Cincinnati Fund. It also shows the amount of
the fees waived by the Adviser for the year ended December 31, 1999, 1998 and
1997.

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

      FEE AND WAIVER             CINCINNATI FUND
- ------------------------------------------------------
- ---------------------------- -------------------------
 1999 Fee Earned                      $117,111
- ------------------------------------------------------
 1999 Fee Waived                             0
                                 -------------
- ------------------------------------------------------
 1999 Fee Paid                        $117,111
- ------------------------------------------------------
 1998 Fee Earned                      $118,179
 1998 Fee Waived                             0
                                --------------
 1998 Fee Paid                        $118,179
                                      ========
- ------------------------------------------------------
 1997 Fee Earned                       $65,378
 1997 Fee Waived                         1,281
                                     ---------
 1997 Fee Paid                         $64,097
                                       =======
- ------------------------------------------------------



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



CUSTODIAN

         Firstar Bank, N.A., 425 Walnut Street, Cincinnati, OH 45202, acts as
custodian of the Trust's assets (the "Custodian"). Under a Custody Agreement
with the Fund, the Custodian holds the Fund's securities and keeps all necessary
accounts and records. The Custodian has no part in determining the investment
policies of the Fund or which securities are to be purchased or sold by the
Fund.




                                       12
<PAGE>   79

SHAREHOLDER SERVICING, TRANSFER, DIVIDEND DISBURSING, AND FINANCIAL SERVICING
AGENT

         The Adviser is the Trust's Shareholder Servicing, Transfer, Dividend
Disbursing, and Financial Servicing Agent (the "Servicing Agent"). The Adviser's
mailing address for its activities as Servicing Agent is The Gateway Trust, 400
TechneCenter Drive, Suite 220, Milford, OH 45150. As Transfer Agent for the
Trust, the Servicing Agent's general duties include transferring shares,
processing applications for new accounts, depositing the payments for the
purchase of Fund shares with the Custodian, and notifying the Trust and
Custodian of such deposits. The Servicing Agent opens and maintains a bookshare
account for each shareholder as set forth in the subscription application,
maintains records of each shareholder account, and sends confirmation of shares
purchased to each shareholder. The Servicing Agent also receives and processes
requests by shareholders for redemption of shares. If the shareholder request
complies with the redemption standards of the Trust, the Servicing Agent will
direct the Custodian to pay the appropriate redemption price. If the redemption
request does not comply with such standards, the Servicing Agent will promptly
notify the shareholder of the reasons for rejecting the redemption request.

         As the Dividend Disbursing Agent for the Trust, the Servicing Agent,
upon notification of the declaration of a dividend or distribution, will
determine the total number of shares issued and outstanding as of the record
date for the dividend or distribution and the amount of cash required to satisfy
such dividend or distribution. The Servicing Agent will prepare and mail to
shareholders dividend checks in the amounts to which they are entitled. In the
case of shareholders participating in the dividend reinvestment plan, the
Servicing Agent will make appropriate credits to their bookshare accounts.
Shareholders will be notified by the Servicing Agent of any dividends or
distributions to which they are entitled, including any amount of additional
shares purchased with their dividends. In addition, the Servicing Agent will
prepare and file with the Internal Revenue Service and with any state, as
directed by the Trust, returns for reporting dividends and distributions paid by
such fund.

         The Servicing Agent, as the Shareholder Servicing Agent, will open and
maintain any plan or program for shareholders in accordance with the terms of
such plans or programs (see "SHAREHOLDER SERVICES" herein). With regard to the
Systematic Withdrawal Program, the Servicing Agent will process such Systematic
Withdrawal Program orders as are duly executed by shareholders and will direct
appropriate payments to be made by the Custodian to the shareholder. In
addition, the Servicing Agent will process such accumulation plans, group
programs, and other plans or programs, for investing shares as provided in the
Fund's current prospectus.


         The Fund reimburses the Servicing Agent for printing, mailing, and
compliance expenses. The Fund compensates the Servicing Agent for these
services, at a fixed rate of $4,000 per month, plus the greater of $2,500 per
month, or an annual rate of 0.20% of the Fund's average net assets. For the year
ended December 31, 1999, the Adviser was paid $173,196 in its capacity as
Servicing Agent to the Gateway Small Cap Index Fund and the Cincinnati Fund.



                                    BROKERAGE
                                    ---------

         Transactions on stock exchanges involve the payment of negotiated
brokerage commissions. In the case of securities traded in the over-the-counter
market, there is generally no stated commission but the price usually includes
an undisclosed commission or mark-up.

         In effecting portfolio transactions for the Fund, the Adviser is
obligated to seek best execution, which is to execute the Fund's transaction
where the most favorable combination of price and execution services are
available ("best execution"), except to the extent that it may be permitted to
pay higher brokerage commissions for brokerage and research services as
described below. In seeking the best execution, the Adviser, in the Fund's best
interest, considers all relevant factors, including:

     -   price;
     -   the size of the transaction;
     -   the nature of the market for the security;
     -   the amount of commission;
     -   the timing of the transaction taking into account market prices and
         trends;
     -   the reputation, experience, and financial stability of the
         broker-dealer involved;
     -   the quality of service rendered by the broker-dealer in other
         transactions.



                                       13
<PAGE>   80

         Consistent with the Rules of Fair Practice of the National Association
of Securities Dealers, Inc. and subject to seeking best execution and such other
factors as the Trustees may determine, the Adviser may consider sales of shares
of the Fund as a factor in the selection of broker-dealers to execute securities
transactions for the Fund.

         While the Adviser does not intend to limit the placement of orders to
any particular broker or dealer, the Adviser generally gives preference to those
brokers or dealers who are believed to give best execution at the most favorable
prices and who also provide research, statistical, or other services to the
Adviser and/or the Trust. Commissions charged by brokers who provide these
services may be higher than commissions charged by those who do not provide
them. Higher commissions are paid only if the Adviser determines that they are
reasonable in relation to the value of the services provided, and it has
reported to the Board of Trustees of the Trust on a periodic basis to that
effect. The availability of such services was taken into account in establishing
the Advisory Fee. Specific research services furnished by brokers through whom
the Trust effects securities transactions may be used by the Adviser in
servicing all of its accounts. Similarly, specific research services furnished
by brokers who execute transactions for other Adviser clients may be used by the
Adviser for the benefit of the Trust.


         The Adviser has an agreement with Bridge Information Systems, Inc.
("Bridge") and an agreement with S&P Securities to direct brokerage transactions
to them in exchange for research services provided to the Adviser. For the
fiscal year ended December 31, 1999, the Trust paid brokerage commissions to
Bridge of $171,451 for effecting brokerage transactions totaling $201,929,680.
During the same period, the Trust paid brokerage commissions to S&P Securities
of $25,840 for effecting brokerage transactions totaling $47,266,728. The
Adviser may from time to time enter into similar agreements with other brokers.


         The Adviser Contract provides that, subject to such policies as the
Trustees may determine, the Adviser may cause the Fund to pay a broker-dealer
who provides brokerage and research services to the Adviser an amount of
commission for effecting a securities transaction for the Fund in excess of the
amount of commission which another broker-dealer would have charged for
effecting that transaction. As provided in Section 28(e) of the Securities
Exchange Act of 1934, "brokerage and research services" include:

     -   advice as to the value of securities, the advisability of investing in,
         purchasing, or selling securities, and the availability of securities,
         or purchasers, or sellers of securities;
     -   furnishing analyses and reports concerning issuers, industries,
         securities, economic factors and trends, portfolio strategy, and
         performance of accounts;
     -   effecting securities transactions and performing functions incidental
         thereto (such as clearance and settlement);
     -   services that provide lawful and appropriate assistance to the Adviser
         in the performance of its investment decision-making responsibilities.


         For the years ended December 31, 1999, 1998, and 1997., the Fund paid
$22,301, $11,635, and $10,885, respectively, in brokerage commissions. Total
commissions paid in 1999 had increased relative to previous years due to an
increase in shareholder redemption requests for 1999.


ADDITIONAL TAX MATTERS

         The tax discussion set forth below and in the Cincinnati Prospectus is
included for general information only. Prospective investors should consult
their own tax advisers concerning the tax consequences of an investment in the
Fund.

FEDERAL TAX MATTERS

         The Fund is treated as a separate association taxable as a corporation.

         The Fund has met and intends to meet the requirements of the Internal
Revenue Code, applicable to regulated investment companies so as to qualify for
the special tax treatment afforded to such companies. Under Subchapter M of the
Code, a regulated investment company is not subject to federal income tax on the
portion of its net investment income and net realized capital gains which it
distributes currently to its shareholders, provided that certain distribution
requirements are met, including the requirement that at least 90% of the sum of
its net investment income and net short-term capital gains in any fiscal year is
so distributed. In addition to this



                                       14
<PAGE>   81

distribution requirement, one of the principal tests which the Fund must meet in
each fiscal year in order to qualify as a regulated investment company is the
"90% Test." The 90% Test requires that at least 90% of a fund's gross income
must be derived from dividends, interest, and gains from the sale or other
disposition of securities.

         Long-term capital gains distributions (i.e., the excess of any net
long-term capital gains over net short-term capital losses), after utilization
of available capital-loss carryforwards, are taxable as long-term capital gains
whether received in cash or additional shares, regardless of how long the
shareholder has held his or her shares, and are not eligible for the
dividends-received deduction for corporations. Distributions of long-term
capital gains which are offset by available loss carryforwards, however, may be
taxable as ordinary income.

         Distributions on shares of the Fund received shortly after their
purchase, although substantially in effect a return of capital, are subject to
federal income taxes.

         The tax status of distributions made by the Fund during the fiscal year
will be sent to shareholders shortly after the end of such year. Each
prospective investor is advised to consult his or her own tax adviser.
Distributions of net investment income are taxable as ordinary income subject to
allowable exclusions and deductions. Distributions of capital gains are taxable
at either ordinary or long-term capital gains rates, as appropriate, except that
all such gains are normally taxable as ordinary income to the extent they are
offset by capital- loss carryforwards.

STATE AND LOCAL TAX ASPECTS

         The laws of several state and local taxing authorities vary with
respect to taxation, and each prospective investor is advised to consult his or
her own tax adviser as to the status of his or her shares and distributions in
respect of those shares under state and local tax laws.


                                 CODE OF ETHICS
                                 --------------

The Gateway Trust and Gateway Investment Advisers L.P. have each adopted a Code
of Ethics which permit employees subject to the codes to invest in securities,
including securities that may be purchased or held by the Cincinnati Fund, on a
limited basis.

                       TRUSTEES AND OFFICERS OF THE TRUST
                       ----------------------------------

         The Board of Trustees is generally responsible for management of the
business and affairs of the Trust. The Trustees formulate the general policies
of the Trust, approve contracts, and authorize the Trust officers to carry out
the decisions of the Board.

         Under the Trust's Second Amended Agreement and Declaration of Trust, no
annual or regular meetings of shareholders are required. As a result, the
Trustees will continue in office until resignation, retirement, death, or
removal. Trustee vacancies normally are filled by vote of the remaining
Trustees. If at any time less than a majority of the Trustees in office have
been elected by the shareholders, the Trustees must call a shareholder meeting
for the purpose of electing Trustees.

         The Trustees and officers of the Trust, together with information as to
their positions with the Trust and its predecessor, Gateway Option Income Fund,
Inc. (the "Company") and their principal occupations during at least the past
five years, are listed below.


         *Walter Gene Sall, 400 TechneCenter Drive, Suite 220, Milford, OH
45150; Chairman and Trustee of the Trust; Chairman of the Adviser; various
senior management positions and offices held with the Trust, the Company, and
the Adviser since 1977. Age 55.

         *J. Patrick Rogers, 400 TechneCenter Drive, Suite 220, Milford, OH
45150; Trustee of the Trust since December 1998; President of the Trust since
1997; President of the Adviser since 1995; portfolio manager of the Funds since
1997; co-portfolio manager of the Funds from 1995 to 1997; various senior
management positions and offices held with the Trust and the Adviser since 1989.
Age 36.




                                       15
<PAGE>   82


         James M. Anderson, Children's Hospital Medical Center, 3333 Burnet
Avenue, Cincinnati, OH 45229; Trustee of the Trust since April 1997; Children's
Hospital Medical Center, President and Chief Executive Officer since November
1996, Chairman of the Board of Trustees from 1992 through 1996, and Trustee
since 1979; Taft Stettinius & Hollister (law firm), Partner from 1982 to
November 1996; Access Corporation (software distributor), Secretary from 1985 to
1996, Consultant from 1996 to 1997, and Director 1997 to 1998; Cincinnati Stock
Exchange, Trustee since 1978; River City Insurance Limited, Director since 1991.
Age 58.

         Stefen F. Brueckner, ProMutual Group, Inc., P. O. Box 9178, Boston, MA
02205; Trustee of the Trust since October 1992; President and Chief Executive
Officer, ProMutual Group (a professional liability insurance company) since
1998; Director, President, and Chief Executive Officer, Anthem Companies, Inc.
(health insurer) 1995 to 1998; Director and President of Community Mutual
Insurance Company (health insurer) from 1991 to 1995, and various management
positions from 1986 to 1991. Age 50.

         Kenneth A. Drucker, Sequa Corp., 200 Park Avenue, New York, NY 10166;
Director of the Company from January 1984 to May 1986; Trustee of the Trust
since April 1986; Vice President and Treasurer, Sequa Corporation (gas turbine
and industrial equipment) since November 1987. Age 54.

         Beverly J. Fertig, 8591 Woodbriar Drive, Sarasota, FL 34238; Trustee of
the Trust since September 1988; arbitrator, National Association of Securities
Dealers, Inc., since January 1992; Vice President, Marketing and Communications,
Coffee, Sugar and Cocoa Exchange from January 1989 to December 1991; Executive
Director, National Institutional Options and Futures Society, March 1988 to
December 1988; prior thereto, Vice President, Institutional Marketing, Chicago
Board Options Exchange. Age 69.

         R. S. (Dick) Harrison, 4040 Mt. Carmel Road, Cincinnati, OH 45244;
Director of the Company from 1977 to 1982; Trustee of the Trust since April
1996; Director/Chairman of the Board, Baldwin Piano & Organ Company from 1994 to
1997; Chairman of the Board/CEO, Baldwin Piano & Organ Company from 1983 to
1994. Prior thereto, various management positions with Baldwin Piano & Organ
Company, Cincinnati, OH. Director of Anderson Bank of Cincinnati, OH and Trustee
of Kenyon College. Age 67.

         William Harding Schneebeck, 251 Indian Harbor Road, Vero Beach, FL
32963; Director of the Company from September 1977 to May 1986; Trustee of the
Trust since April 1986; retired, formerly Chairman of Midwestern Fidelity Corp.
Age 70.

         James E. Schwab, XTEK, Inc., 11451 Reading Road, Cincinnati, OH
45241-2283; Trustee of the Trust since December 1998; President of XTEK, Inc. (a
manufacturing company), from November 1995 to present, Vice President of XTEK,
Inc. from October 1994 to November 1995; various executive positions with
American Financial Corporation and its affiliates from 1985 to 1994, including
Senior Vice President of General Cable Corporation from 1992 to 1994 and Senior
Vice President of the Penn Central Corporation (now called the American
Financial Group) from 1989 to 1992. Age 56.

         *Geoffrey Keenan, 400 TechneCenter Drive, Suite 220, Milford, OH 45150;
Vice President of the Trust since April 1996; Chief Operating Officer, Gateway
Investment Advisers, L.P. since December 1995; Executive Vice President and
Chief Operating Officer, Gateway Investment Advisers, Inc. since 1995; Vice
President, Gateway Investment Advisers, Inc. from 1991 to 1995. Age 41.

         *Paul R. Stewart, 400 TechneCenter Drive, Suite 220, Milford, OH 45150;
Treasurer of the Trust since October 1995; Chief Financial Officer of the
Adviser since 1996, Controller of the Adviser from October 1995 to December
1996; Audit Manager and Senior, Price Waterhouse from September 1992 to 1995 and
from August 1988 to August 1991. Age 34.

         *Donna M. Squeri, 400 TechneCenter Drive, Suite 220, Milford, OH 45150;
Secretary of the Trust since October 1995; Secretary and General Counsel of the
Adviser since September 1995; in-house counsel of Bartlett & Co., a registered
investment adviser, from October 1984 to September 1993. Age 40.


         *Messrs. Sall, Rogers, Keenan, Stewart, and Ms. Squeri are affiliated
persons of the Trust and the Adviser as defined by the Investment Company Act of
1940. Mr. Sall and Mr. Rogers are "interested persons" of the Trust as defined
by the Investment Company Act of 1940.




                                       16
<PAGE>   83

         Messrs. Sall, Rogers, Keenan, Stewart, and Ms. Squeri each of whom is
employed by the Adviser, receive no remuneration from the Trust. Each Trustee of
the Trust other than Mr. Sall and Mr. Rogers receive fees as follows: (a) an
annual fee of $3,000, payable in equal quarterly installments for services
during each fiscal quarter; (b) a $500 base fee plus $100 per fund for each
regular or special meeting of the Board of Trustees attended; and (c) $200 per
fund ($1,000 per fund for the Chairman) for each Audit Committee meeting
attended. The Trust also reimburses each Trustee for any reasonable and
necessary travel expenses incurred in connection with attendance at such
meetings. In addition, Trustees may receive attendance fees for service on other
committees.


         The following table provides information about the compensation
received by each Trustee from the Trust for the year ended December 31, 1999.

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

      NAME OF TRUSTEE           TOTAL COMPENSATION
                                    FROM TRUST
- ---------------------------- --------------------------
James M. Anderson                    $  4,600
Stefen F. Brueckner                  $  6,200
Kenneth A. Drucker                   $ 12,200
Beverly J. Fertig                    $  6,200
R. S. Harrison                       $  6,600
J. Patrick Rogers                    $      0
Walter G. Sall                       $      0
William H. Schneebeck                $  7,400
James E. Schwab                      $  6,200
- ---------------------------- --------------------------


SHAREHOLDER MEETINGS AND VOTING

         A meeting of shareholders must be called if shareholders holding at
least 10% of the Trust's shares (or shareholders holding at least 10% of any
fund's shares as to any matter affecting only such fund) file a written request
for a meeting.


         On any matter submitted to a vote of shareholders, shares are voted by
fund, unless an aggregate vote is required by the Investment Company Act of
1940. Shares are voted by fund with respect to the approval or amendment of such
fund's advisory contract. As of April 4, 2000, the Adviser held, in a fiduciary
capacity, more than 25% of the outstanding shares of the Small Cap Index Fund.
Thus, the Adviser may be deemed to be a control person of this Fund as of that
date. As of April 4, 2000, DB Alex. Brown LLC held more than 25% of the
outstanding shares of the Gateway Fund. Thus, DB Alex. Brown LLC may be deemed
to be a control person of this Fund as of that date.

         As of April 3, 2000, the shareholders of the Gateway Fund controlled
approximately 95.64% of the outstanding shares of the Trust. Therefore, in the
foreseeable future, when the shareholders of the Trust elect the Trustees or
vote in the aggregate on any other issue, the shareholders of the Gateway Fund
will be able to elect the Trustees or to decide the issue. Shareholders do not
have cumulative voting rights as to the election of Trustees. As a result, if a
shareholder meeting is called to elect Trustees, a majority of the shares voting
at the meeting can elect all of the Trustees.



             INDEPENDENT PUBLIC ACCOUNTANTS AND FINANCIAL STATEMENTS
             -------------------------------------------------------

         Arthur Andersen LLP, 425 Walnut Street, Cincinnati, OH 45202, will
serve as independent public accountants of the Trust. Arthur Andersen LLP
performs an annual audit of the Fund's financial statements, reviews the Fund's
tax returns, and provides financial, tax, and accounting consulting services as
requested.

                   PRINCIPAL HOLDERS OF CINCINNATI FUND SHARES
                   -------------------------------------------




                                       17
<PAGE>   84


         As of April 4, 2000, the Fund had 824,455.922 shares outstanding, out
of an unlimited number of authorized shares. As of such date, each of the
following persons or groups was known by Trust management to be the record
and/or beneficial owner (as defined below) of the indicated amounts of the
Fund's outstanding shares.

<TABLE>
<CAPTION>

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

                      NAME AND ADDRESS OF OWNER                        NUMBER OF SHARES             PERCENT OF CLASS
      -------------------------------------------------------------------------------------------------------------------
<S>                                                                      <C>                             <C>
      BAND and Co.
      Firstar Bank, N.A.                                      113,763                         13.80%

      P. O. Box 640229
      Cincinnati, OH  45264
      Up East, Inc.                                                         42,291                          5.25%
      c/o Betsy J. Wyeth
      P.O. Box 48
      Chadds Ford, PA  19317
      Trustees and officers of the Trust as a group                         36,051                          4.37%
      Adviser officers & directors as a group                               11,219                          1.36%
      ---------------------------------------------------------- ------------------------------ -------------------------
</TABLE>


         The SEC has defined "beneficial owner" of a security to include any
person who has voting power or investment power with respect to any such
security, any person who shares voting power or investment power with respect to
any such security, or any person who has the right to acquire beneficial
ownership of any such security within 60 days.


         As of April 3, 2000, the Adviser held in a fiduciary capacity 48,422
(5.87%) of the outstanding shares of the Fund. The Adviser has investment and
voting power over all shares held by it in a fiduciary capacity.



                                   SCHEDULE A
                                   ----------

         The beta measurements that may be used in the Cincinnati Prospectus
were calculated by using Microsoft Excel spreadsheets and the statistical
function slope available in Microsoft Excel. The SLOPE function returns the
slope of the linear regression line through data points in known y's and known
x's. The slope is the vertical distance divided by the horizontal distance
between any two points on the line, which is the rate of change along the
regression line.

       The equation for beta (slope) is shown below.

                  [EQUATION OMITTED]



       Where    y = the Fund's monthly total returns in the period
                x = the benchmark index's monthly total returns in the period




                                       18
<PAGE>   85
PART C: OTHER INFORMATION

ITEM 23.    Exhibits:
- --------

            (a)   ARTICLES OF INCORPORATION

                  Registrant's Second Amended Agreement and Declaration of Trust
                  dated December 29, 1992 is incorporated by reference to
                  Exhibits to Registrant's Post-Effective Amendment No. 31
                  (Investment Company Act No. 29) to Registration Statement No.
                  2-59895 filed with the Securities and Exchange Commission on
                  April 30, 1998.

                  Amendment No. 1 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.

                  Amendment No. 2 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.

                  Amendment No. 3 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.

                  Amendment No. 4 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.

                  Amendment No. 5 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.

                  Amendment No. 6 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to


<PAGE>   86

                  Registration Statement No. 2-59895 filed with the Securities
                  and Exchange Commission on April 30, 1998.

                  Amendment No. 7 to Registrant's Second Amended Agreement and
                  Declaration of Trust is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.

            (b)   BYLAWS

                  Registrant's By-Laws as restated dated October 29, 1996 are
                  incorporated by reference to Exhibits to Registrant's
                  Post-Effective Amendment No. 30 (Investment Company Act No.
                  28) to Registration Statement No. 2-59895 filed with the
                  Securities and Exchange Commission on February 28, 1997.

                  Amendment to Section 2.5 of Registrant's By-Laws, effective
                  September 24, 1998, is incorporated by reference to Exhibits
                  to Registrant's Post-Effective Amendment No.32 (Investment
                  Company Act No 30) to Registration Statement No. 2-59859 filed
                  with the Securities and Exchange Commission on November 2,
                  1998.

            (c)   INSTRUMENTS DESCRIBING RIGHTS OF SECURITY HOLDERS

                  None.

            (d)   INVESTMENT ADVISORY CONTRACTS

                  Investment Advisory Contract between the Gateway Fund and
                  Gateway Investment Advisers, L.P. is incorporated by reference
                  to Exhibits to Registrant's Post-Effective Amendment No.33
                  (Investment Company Act No. 31) to Registration Statement No.
                  2-59895 filed with the Securities and Exchange Commission on
                  March 2, 1999..

                  Investment Advisory Contract between the Gateway Small Cap
                  Index Fund and Gateway Investment Advisers, L.P. is
                  incorporated by reference to Exhibits to Registrant's
                  Post-Effective Amendment No. 29 (Investment Company Act No.
                  27) to Registration Statement No. 2-59895 filed with the
                  Securities and Exchange Commission on February 29, 1996.

                  Investment Advisory Contract between the Cincinnati Fund and
                  Gateway Investment Advisers, L.P. is incorporated by reference
                  to Exhibits to Registrant's Post-Effective Amendment No. 29
                  (Investment Company Act No. 27) to Registration Statement No.
                  2-59895 filed with the Securities and Exchange Commission on
                  February 29, 1996.


<PAGE>   87

            (e)   UNDERWRITING CONTRACTS

                  None.

            (f)   BONUS OR PROFIT SHARING CONTRACTS

                  None.

            (g)   CUSTODIAN AGREEMENTS

                  Custodian Contract between Registrant and The First National
                  Bank of Cincinnati, N.A. (now Firstar Corporation) with
                  respect to the Gateway Option Index Fund (now the Gateway
                  Fund) is incorporated by reference to Exhibits to Registrant's
                  Post-Effective Amendment No. 31 (Investment Company Act No.
                  29) to Registration Statement No. 2-59895 filed with the
                  Securities and Exchange Commission on April 30, 1998.

                  Custodian Contract between Registrant and Firstar Corporation
                  with respect to the Gateway Small Cap Index Fund is
                  incorporated by reference to Exhibits to Registrant's
                  Post-Effective Amendment No. 31 (Investment Company Act No.
                  29) to Registration Statement No. 2-59895 filed with the
                  Securities and Exchange Commission on April 30, 1998.

                  Custodian Contract between Registrant and Firstar Corporation
                  with respect to the Gateway Cincinnati Fund is incorporated by
                  reference to Exhibits to Registrant's Post-Effective Amendment
                  No. 31 (Investment Company Act No. 29) to Registration
                  Statement No. 2-59895 filed with the Securities and Exchange
                  Commission on April 30, 1998.

            (h)   OTHER MATERIAL CONTRACTS

                  Services Agreement dated January 1, 1998 between Registrant
                  and Gateway Investment Advisers, L.P. with respect to the
                  Gateway Fund, the Gateway Small Cap Index Fund, and the
                  Cincinnati Fund is incorporated by reference to Exhibits to
                  Registrant's Post-Effective Amendment No. 31 (Investment
                  Company Act No. 29) to Registration Statement No. 2-59895
                  filed with the Securities and Exchange Commission on April 30,
                  1998.



            (i)   LEGAL OPINION

                  Opinion of Brown, Cummins & Brown Co., L.P.A. is incorporated
                  by reference to Registrant's Form 24F-2 for the year ending
                  December 31,

<PAGE>   88


                  1996. Consent of Brown, Cummins & Brown Co., L.P.A is filed
                  herewith.

            (j)   OTHER OPINIONS

                  Consent of Arthur Andersen LLP is filed herewith.

            (k)   OMITTED FINANCIAL STATEMENTS

                  None.

            (l)   INITIAL CAPITAL AGREEMENTS

                  None.

            (m)   RULE 12b-1 PLAN

                  The Gateway Fund's Distribution Plan pursuant to Rule 12b-1
                  under the Investment Company Act of 1940 is incorporated by
                  reference to Exhibits to Registrant's Post-Effective Amendment
                  No. 33 (Investment Company Act No. 31) to Registration
                  Statement No. 2-59895 filed with the Securities and Exchange
                  Commission on March 2, 1999.


            (n)   RULE 18f-3 PLAN

                  None.

            (o)   RESERVED



            (p)   CODE OF ETHICS

                  (1)      The Code of Ethics for the Gateway Trust adopted
                           under rule 17j-1 of the Investment Company Act of
                           1940 is filed herewith.

                  (2)      The Code of Ethics for Gateway Investment Advisers,
                           L.P. adopted under rule 17j-1 of the Investment
                           Company Act of 1940 is filed herewith.



            (q)   POWERS OF ATTORNEY FOR THE TRUSTEES OF THE REGISTRANT ARE
                  FILED HEREWITH.


ITEM 24.    PERSONS CONTROLLED BY OR UNDER COMMON CONTROL WITH REGISTRANT


            None


<PAGE>   89

ITEM 25.    INDEMNIFICATION

            The Second Amended Agreement and Declaration of Trust of the
            Registrant dated as of December 29, 1992 (the "Declaration of
            Trust"), provides for the indemnification of the trustees, officers,
            employees and agents of the Registrant. Such indemnification is
            mandatory to the extent that such trustee, officer, employee or
            agent is successful on the merits or otherwise in defense of any
            claim, issue or matter arising out of any action, suit or
            proceeding. In all other cases, trustees, directors, officers,
            employees and agents of the Registrant may be indemnified by the
            Registrant provided that the requirements for such indemnification
            set forth in the Declaration of Trust are fulfilled. These
            indemnification provisions, which were amended by vote of the
            shareholders in October 1990 and became effective on January 30,
            1991, generally follow the indemnification provisions authorized by
            Ohio law for Ohio corporations as of May 1986, but include
            supplemental provisions designed to comply with requirements of the
            Investment Company Act of 1940.

            The Registrant will not indemnify any person if such indemnification
            would be unlawful under the Securities Act of 1933 or the Investment
            Company Act of 1940.

            Insofar as indemnification for liability arising under the
            Securities Act of 1933 may be permitted to trustees, directors,
            officers and controlling persons of the Registrant pursuant to the
            foregoing provisions, or otherwise, the Registrant has been advised
            that in the opinion of the Securities and Exchange Commission such
            indemnification is against public policy as expressed in the Act and
            is, therefore, unenforceable. In the event that a claim for
            indemnification against such liabilities (other than the payment by
            the Registrant of expenses incurred or paid by a trustee, director,
            officer or controlling person of the Registrant in the successful
            defense of any action, suit or proceeding) is asserted by such
            trustee, director, officer or controlling person in connection with
            the securities being registered, the Registrant will, unless in the
            opinion of its counsel the matter has been settled by controlling
            precedent, submit to a court of appropriate jurisdiction the
            question whether such indemnification by it is against public policy
            as expressed in the Act and will be governed by the final
            adjudication of such issues.


ITEM 26.    BUSINESS AND OTHER CONNECTIONS OF INVESTMENT ADVISER


            Gateway Investment Advisers, L.P. (the "Adviser") the general
            partner of which is Gateway Investment Advisers, Inc. (the "GIA") is
            the investment adviser to the Trust and to other individually
            managed accounts as well. One of the limited partners of the
            Adviser, Alex. Brown Investments Incorporated ("ABII") is a
            wholly-owned subsidiary of Deutsche Bank. ABII's primary function is
            to acquire investment interests in various entities for investment
            purposes only.



<PAGE>   90

ITEM 27.    PRINCIPAL UNDERWRITERS

            None.

ITEM 28.    LOCATION OF ACCOUNTS AND RECORDS

            Accounts, books and other documents required to be maintained by
            Section 31(a) of the Investment Company Act of 1940 and the rules
            promulgated thereunder are maintained by Gateway Investment
            Advisers, L.P., located at 400 TechneCenter Drive, Suite 220,
            Milford, Ohio 45150.



ITEM 29.    MANAGEMENT SERVICES

            None.

ITEM 30.    UNDERTAKINGS

                                      None

<PAGE>   91


                                   SIGNATURES



         Pursuant to the requirements of the Securities Act of 1933 and the
Investment Company Act of 1940, the Registrant certifies that it meets all of
the requirements for effectiveness of this registration statement under rule
485(b) under the Securities Act and has duly caused this Post-Effective
Amendment to the Registrant's Registration Statement to be signed on its behalf
by the undersigned, thereto duly authorized, in the City of Milford and the
State of Ohio on the 28th day of April, 2000.


                                            THE GATEWAY TRUST


                                            By: /s/ J. Patrick Rogers
                                                --------------------------------
                                                J. Patrick Rogers, President



         Pursuant to the requirements of the Securities Act of 1933, this
Post-Effective Amendment to the Registrant's Registration Statement has been
signed below by the following persons in the capacities and on the date
indicated.



Dated:  April 28th, 2000                       /s/ J. Patrick Rogers
                                               ---------------------------------
                                               J. Patrick Rogers, President


Dated:  April 28th, 2000                       /s/ Gary H. Goldschmidt
                                               ---------------------------------
                                               Treasurer and
                                               Principal Accounting Officer

                                               ---------------------------------
James M. Anderson, Trustee
Stefen F. Brueckner, Trustee
Kenneth A. Drucker, Trustee
Beverly J. Fertig, Trustee
Robert S. Harrison, Trustee
J. Patrick Rogers, Trustee and President
Walter G. Sall, Trustee, Chairman and
Principal Executive Officer                    By: /s/ J. Patrick Rogers
William H. Schneebeck, Trustee                     ---------------------
James E. Schwab, Trustee                           J. Patrick Rogers
                                                   Dated: April 28, 2000




<PAGE>   92


                                 Securities Act of 1933 Registration No. 2-59895
                       Investment Company Act of 1940 Registration No. 811-02773







                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.


                                    FORM N-1A


             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933


                          Post-Effective Amendment No. 35




         REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940


                         Post-Effective Amendment No. 33




                                THE GATEWAY TRUST


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

                                    EXHIBITS

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



<PAGE>   93


                                  EXHIBIT INDEX

<TABLE>
<CAPTION>

EXHIBIT NUMBER                  DESCRIPTION OF EXHIBIT                                   EXHIBIT TAG
<S>                   <C>                                                                <C>
               1.     Consent of Arthur Andersen LLP                                     Ex-99.23.j

               2.     Powers of Attorney                                                 Ex-99.23.q

               3.     Consent of Counsel                                                 EX-99.23.i

               4.     Code of Ethics for the Gateway Trust                               EX-99.23.p.1

               5.     Code of Ethics for Gateway Investment Advisers, L.P.               EX-99.23.p.2

</TABLE>



<PAGE>   1
                                                                     Exhibit (j)

                    CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS

         As independent public accountants, we hereby consent to the
incorporation by reference in this Post-Effective Amendment No. 35 of our audit
reports on the financial statements of the Gateway Fund, Gateway Small Cap Index
Fund and Cincinnati Fund of The Gateway Trust, dated January 19, 2000, and to
all references to our Firm included in or made a part of this Post-Effective
Amendment No. 35.


                                                 /s/ Arthur Andersen LLP
                                                 -----------------------
                                                 ARTHUR ANDERSEN LLP

Cincinnati, Ohio,
   April 28, 2000


<PAGE>   1
                                                                      Exhibit 99

                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                                 /s/ James M. Anderson
                                                 -------------------------
                                                 James M. Anderson, Trustee

State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared James M. Anderson, known to me to be the person described in
and who executed the foregoing instrument, and who acknowledged to me that he
executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                                 /s/ Donna M. Squeri
                                                 -------------------
                                                 Donna M. Squeri
                                                 Notary Public, State of Ohio
                                                 My commission has no expiration


<PAGE>   2


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ Stefen F. Brueckner
                                             -----------------------
                                             Stefen F. Brueckner, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared Stefen F. Brueckner, known to me to be the person described
in and who executed the foregoing instrument, and who acknowledged to me that he
executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             -------------------
                                             Donna M. Squeri
                                             Notary Public, State of Ohio
                                             My commission has no expiration


<PAGE>   3


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ Kenneth A. Drucker
                                             ----------------------
                                             Kenneth A. Drucker, Trustee

State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared Kenneth A. Drucker , known to me to be the person described
in and who executed the foregoing instrument, and who acknowledged to me that he
executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             -------------------
                                             Donna M. Squeri
                                             Notary Public, State of Ohio
                                             My commission has no expiration


<PAGE>   4


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ Beverly J. Fertig
                                             ---------------------
                                             Beverly J. Fertig, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared Beverly J. Fertig, known to me to be the person described in
and who executed the foregoing instrument, and who acknowledged to me that he
executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             -------------------
                                             Donna M. Squeri
                                             Notary Public, State of Ohio
                                             My commission has no expiration


<PAGE>   5


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ Robert S. Harrison
                                             ----------------------
                                             Robert S. Harrison, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared Robert S. Harrison, known to me to be the person described
in and who executed the foregoing instrument, and who acknowledged to me that he
executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             -------------------
                                             Donna M. Squeri
                                             Notary Public, State of Ohio
                                             My commission has no expiration


<PAGE>   6


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ J. Patrick Rogers
                                             ---------------------
                                             J. Patrick Rogers, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared William H. Schneebeck, known to me to be the person
described in and who executed the foregoing instrument, and who acknowledged to
me that he executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             -------------------
                                             Donna M. Squeri
                                             Notary Public, State of Ohio

         My commission has no expiration
<PAGE>   7
                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ Walter G. Sall
                                             ------------------
                                             Walter G. Sall, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared Walter G. Sall, known to me to be the person described in
and who executed the foregoing instrument, and who acknowledged to me that he
executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             Donna M. Squeri
                                             Notary Public, State of Ohio
                                             My commission has no expiration


<PAGE>   8


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ William H. Schneebeck
                                             -------------------------
                                             William H. Schneebeck, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared William H. Schneebeck, known to me to be the person
described in and who executed the foregoing instrument, and who acknowledged to
me that he executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             -------------------
                                             Donna M. Squeri
                                             Notary Public, State of Ohio
                                             My commission has no expiration


<PAGE>   9


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS:

         WHEREAS, THE GATEWAY TRUST, an Ohio business trust (the "Trust"),
proposes to file with the Securities and Exchange Commission under the
provisions of the Securities Act of 1933, as amended, and the rules and
regulations thereunder, and the Investment Company Act of 1940, as amended, and
the rules and regulations thereunder, a post-effective amendment to Registration
Statement No. 2-59895 amending such Registration Statement and the included
prospectuses and statements of additional information for the Trust; and

         WHEREAS, the undersigned is a trustee of the Trust;

         NOW, THEREFORE, the undersigned hereby constitutes and appoints Walter
G. Sall and J. Patrick Rogers, each of them individually, his attorney-in-fact,
for him and in his name, place and stead and in his office and capacity with the
Trust, to execute and file such post-effective amendment, including
prospectuses, statements of additional information and exhibits, and thereafter
to execute and file any additional amended registration statement or statements,
amended prospectus or prospectuses and amended statement or statements of
additional information, or any supplements to any of the foregoing, hereby
giving and granting to said attorney full power and authority to do and perform
each and every act and thing whatsoever requisite and necessary to be done in
and about the premises as fully to all intents and purposes as he might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do or cause to be done by virtue
hereof.

         This authority hereby granted is limited to the execution and delivery
of such post-effective amendment and included documents and, unless earlier
revoked by me or expressly extended by me in writing, shall remain in force and
effect only until such post-effective amendment shall have been declared
effective by the Securities and Exchange Commission and in any event not later
than May 15, 2000.

         IN WITNESS WHEREOF, the undersigned has hereunto set his hand this 25th
day of January, 2000.


                                             /s/ James E. Schwab
                                             -------------------
                                             James E. Schwab, Trustee


State of Ohio
County of Clermont

         Before me, a Notary Public, in and for said county and state,
personally appeared William H. Schneebeck, known to me to be the person
described in and who executed the foregoing instrument, and who acknowledged to
me that he executed and delivered the same for the purpose therein expressed.

         WITNESS my hand and official seal this 25th day of January, 2000.


                                             /s/ Donna M. Squeri
                                             Donna M. Squeri
                                             Notary Public, State of Ohio

         My commission has no expiration


<PAGE>   1

                                                                     Exhibit (i)

                       BROWN, CUMMINS & BROWN CO., L.P.A.
                         ATTORNEYS AND COUNSELORS AT LAW
                                3500 CAREW TOWER
                                 441 VINE STREET
                             CINCINNATI, OHIO 45202
                            TELEPHONE (513) 381-2121
                            TELECOPIER (513) 381-2125



                                 April 27, 2000


The Gateway Trust
400 TechneCenter Drive, Suite 220
Milford, Ohio  45150

Gentlemen:

         A legal opinion that we prepared was filed with your Form 24f-2 for the
fiscal year ended December 31, 1996 (the "Legal Opinion"). We hereby give your
our consent to incorporate by reference the Legal Opinion into Post-Effective
Amendment No. 35 to your Registration Statement (the Amendment"), and consent to
all references to us in the Amendment.

                                          Very truly yours,

                                          /s/ Brown, Cummins & Brown Co., L.P.A.

                                          BROWN, CUMMINS & BROWN CO., L.P.A.

BCB/jlm



<PAGE>   1
                                                                  Exhibit (p)(1)

                                THE GATEWAY TRUST

                                 CODE OF ETHICS

                                JANUARY 25, 2000

This Code of Ethics is based on the principle that every Trustee, director,
officer and employee of The Gateway Trust or any investment adviser to The
Gateway Trust should place the interests of the shareholders of the Trust before
his own personal interests at all times. Each Trustee, director, officer and
employee should avoid any actual or potential conflicts of interest with the
Trust in all personal securities transactions. Each Trustee, director, officer
and employee should comply with the provisions of the Code of Ethics in all his
personal securities transactions.

A.   DEFINITIONS

1.   "Trust" means The Gateway Trust, an Ohio business trust registered under
     the Investment Company Act of 1940.

2.   "Fund" means any portfolio series of the Trust.

3.   "Adviser" means any person who acts as an investment adviser to any Fund.

4.   "Access person" means any trustee or officer of the Trust or any "advisory
     person" of a Fund.

5.   "Advisory person" of a Fund means:

     (a)  any employee of an Adviser ( or of any company in a control
          relationship to an Adviser) who, in connection with his regular
          functions or duties, obtains information regarding the purchase or
          sale of a security by the Fund
     (b)  any natural person in a control relationship to the Fund who obtains
          information concerning recommendations made to the Fund with regard to
          the purchase or sale of a security
     (c)  any "investment representative" of a Fund.



                                     --1--
<PAGE>   2

6.   "Investment representative" of a Fund means:

     (a)  any portfolio manager of the Fund
     (b)  any employee of an Adviser (or of any company in a control
          relationship to an Adviser) who, in connection with his regular
          functions or duties, makes, participates in, or executes the purchase
          or sale of a security by the Fund
     (c)  any employee of an Adviser (or of any company in a control
          relationship to an Adviser) whose functions relate to the making of
          any recommendations with respect to the purchase or sale of a security
          by the Fund.

7.   A security is "being considered for purchase or sale" when a recommendation
     to purchase or sell a security has been made and communicated and, with
     respect to the person making the recommendation, when such person seriously
     considers making such a recommendation. Serious consideration includes the
     act of writing a trade ticket, entering an order with a broker, and time
     stamping the trade ticket.

8.   "Beneficial ownership" will be interpreted in the same manner as it would
     be in determining whether a person is subject to the provisions of Section
     16 of the Securities Exchange Act of 1934 and the rules and regulations
     thereunder, except that the determination of direct or indirect beneficial
     ownership shall apply to all securities which an access person has or
     acquires. For purposes of this Code, "Beneficial ownership" includes, but
     is not limited to, securities held by members of a person's immediate
     family sharing the same household and securities over which a person has
     discretionary authority outside of his ordinary course of business.

9.   "Control" has the same meaning as set forth in Section 2(a)(19) of the
     Investment Company Act.

10.  "Disinterested trustee" means a trustee of the Trust who is not an
     "interested person" of the Trust within the meaning of Section 2(a)(19) of
     the Investment Company Act.

11.  "Purchase or sale of a security" includes the writing of an option to
     purchase or sell a security.



                                     --2--
<PAGE>   3

12.  "Security" has the same meaning as set forth in Section 2(a)(36) of the
     Investment Company Act, except that it does not include the following
     securities (the "Excluded Securities"):

     (a)  shares of registered open-end investment companies
     (b)  securities issued by the United States government
     (c)  short-term debt securities that are "government securities" within the
          meaning of Section 2(a)(16) of the Investment Company Act
     (d)  bankers' acceptances
     (e)  bank certificates of deposit
     (f)  commercial paper
     (g)  such other money market instruments as designated by the Trust's Board
          of Trustees.

A person does not become an "advisory person" or an "investment representative"
simply by virtue of the following activities:

     (a)  normally assisting in the preparation of public reports, or receiving
          public reports, but not receiving information about current
          recommendations or trading; or
     (b)  a single instance of obtaining knowledge of current recommendations or
          trading activity, or infrequently or inadvertently obtaining such
          knowledge.

B.   PROHIBITED PURCHASES AND SALES OF SECURITIES

1.   Prohibited Transactions of Investment Representatives
     -----------------------------------------------------

     (a)  An investment representative of a Fund may not purchase or sell,
          directly or indirectly, any security (in which he has, or by reason of
          such transaction acquires, any direct or indirect beneficial
          ownership) if the Fund has a pending buy or sell order in the same
          security until the Fund's order is executed or withdrawn.

     (b)  An investment representative of a Fund may not purchase or sell,
          directly or indirectly, any security (in which he has, or by reason of
          such transaction acquires, any direct or indirect beneficial
          ownership) if such security is being considered for purchase or sale
          by the Fund.



                                     --3--
<PAGE>   4

(c)  An investment representative of a Fund may not purchase or sell, directly
     or indirectly, any security (in which he has, or by reason of such
     transaction acquires, any direct or indirect beneficial ownership) within
     seven calendar days before or after the execution of a trade in the same
     security by the Fund.

(d)  An investment representative of a Fund may not purchase or sell, directly
     or indirectly, any index option contracts (in which he has, or by reason of
     such transaction acquires, any direct or indirect beneficial ownership).

2.   Prohibited Transactions of Access Persons
     -----------------------------------------

     (a)  An access person may not purchase or sell, directly or indirectly, any
          security (in which he has, or by reason of such transaction acquires,
          any direct or indirect beneficial ownership) if, to his actual
          knowledge, any Fund has a pending buy or sell order in the same
          security until the Fund's order is executed or withdrawn.

     (b)  An access person may not purchase or sell, directly or indirectly, any
          security (in which he has, or by reason of such transaction acquires,
          any direct or indirect beneficial ownership) if, to his actual
          knowledge, such security is being considered for purchase or sale by
          any Fund.

3.   Prohibited Transactions of Employees of the Adviser
     ---------------------------------------------------

          An employee of the Adviser may not purchase or sell, directly or
          indirectly, any index option contracts.

C.   PRECLEARANCE OF SECURITIES TRANSACTIONS

Each access person (other than a disinterested trustee) must obtain approval
from a designated compliance officer for the Trust prior to purchasing or
selling any security, the purchase or sale of which is not prohibited pursuant
to Section B of this Code. Approval will be valid for two trading days.

                                     --4--
<PAGE>   5


D.   EXEMPTED TRANSACTIONS

The prohibitions described in Section B of this Code and the preclearance
requirements set forth in Section C of this Code do not apply to the following
transactions:

     (a)  purchases or sales of Excluded Securities

     (b)  purchases or sales of securities involving less than 2,000 shares of a
          security included in the Standard & Poor's 500 Index

     (c)  purchases or sales of securities involving less than 2,000 shares of a
          security of a company with a market capitalization in excess of $200
          million and average daily trading volume in excess of 50,000 shares

     (d)  purchases or sales of option contracts involving less than 20
          contracts on a security included in the Standard & Poor's 500 Index

     (e)  purchases or sales of option contracts involving less than 20
          contracts on a security of a company with a market capitalization in
          excess of $200 million and average daily trading volume in excess of
          50,000 shares

     (f)  purchases or sales of securities effected in any account over which
          the access person has no direct or indirect influence or control

     (g)  purchases or sales of securities by an access person that are not
          eligible for purchase or sale by any Fund

     (h)  purchases or sales of securities that are nonvolitional on the part of
          either the Fund or the access person
     (i)  purchases of securities that are part of an automatic dividend
          reinvestment plan
     (j)  purchase of securities effected upon the exercise of rights issued by
          an issuer pro rata to all holders of a class of its securities, to the
          extent such rights were acquired from such issuer, or sales of such
          rights.

E.   RESTRICTIONS ON INVESTMENTS IN INITIAL PUBLIC OFFERINGS

An investment representative may not acquire any securities in an initial public
offering without express prior approval from the Trust.



                                     --5--
<PAGE>   6


F.   RESTRICTIONS ON PRIVATE PLACEMENT TRANSACTIONS

An investment representative may not acquire any security of any issuer in a
private placement without express prior approval from the Trust. An investment
representative of a Fund must disclose his investment in such security if he
takes part in the Fund's subsequent decision to invest in any security of the
issuer.

G.   RESTRICTIONS ON SHORT TERM TRADES

An investment representative may not profit from the purchase and sale, or sale
and purchase, of the same or equivalent securities within 60 calendar days
("short-term trade"). This restriction does not apply to the following
short-term trades:

     (a)  a short-term trade involving Excluded Securities
     (b)  a short-term trade for which express prior approval has been received
          from the Trust by the investment representative
     (c)  a short-term trade involving no more than 100 shares of a security
          included in the Standard & Poor's 500 Index
     (d)  a short-term trade involving no more than 100 shares of a security of
          a company with a market capitalization in excess of $200 million and
          average daily trading volume in excess of 50,000 shares
     (e)  a short-term trade involving no more than two option contracts on a
          security included in the Standard & Poor's 500 Index
     (f)  a short-term trade involving no more than two option contracts on a
          security of a company with a market capitalization in excess of $200
          million and average daily trading volume in excess of 50,000 shares
     (g)  a short- term trade in any account over which the investment
          representative has no direct or indirect influence or control
     (h)  a short-term trade that is nonvolitional on the part of the investment
          representative
     (i)  a short-term trade resulting from an automatic dividend reinvestment
          plan.

H.   RESTRICTIONS ON SERVING ON BOARD OF DIRECTORS

An investment representative may not serve on the Board of Directors of a
publicly traded company without express prior approval from the Trust.



                                     --6--
<PAGE>   7

I.   RESTRICTIONS ON ACCEPTANCE OF GIFTS

Neither an access person nor an employee of an Adviser may accept in any
calendar year gifts with a value of more than $100 from any person ("donor")
that does business with or on behalf of the Trust, any Fund or any Adviser. This
restriction does not apply to gifts in the form of an occasional meal, a ticket
to a sporting event, theater or comparable entertainment, or an invitation to
golf or participate in similar sporting activities for such person and his
guests so long as (1) such gifts are neither so frequent nor so extensive as to
raise any question of propriety and (2) such gifts are not preconditioned on the
donor obtaining or maintaining a specified level of business with the Trust, any
Fund or any Adviser.

J.   REPORTING

1.   Reports of Access Persons and Employees of Adviser
     --------------------------------------------------

Each access person and each employee of an Adviser must report to the Trust the
information described in paragraph 3 below for each transaction in any security
in which he has, or by reason of such transaction, acquires, any direct or
indirect beneficial ownership in the security. This reporting requirement does
not apply to access persons and employee transactions listed in Items D(a),(f)
and (g) under Exempted Transactions.

2.   Reports of Disinterested Trustees
     ---------------------------------

Notwithstanding the provisions of paragraph 1 above, a disinterested trustee
must report a transaction in a security only if he knew at the time of the
transaction (or, in the ordinary course of fulfilling his official duties as a
trustee, he should have known at the time of the transaction) that the security
was purchased or sold by any Fund or was being considered for purchase or sale
by any Fund during the fifteen day period immediately preceding the date of the
trustee's transaction.

3.   Form of Reports
     ---------------

Every report must contain the following information:

     (a)  the date of the transaction
     (b)  the title and number of shares (or the principal amount) of the
          security
     (c)  the nature of the transaction (purchase, sale or other type of
          acquisition or disposition)


                                     --7--
<PAGE>   8

     (d)  the price at which the transaction was effected
     (e)  the name of the broker, dealer, bank or other entity through or with
          whom the transaction was effected.

4.   Submission of Reports
     ---------------------

Every report must be submitted to the Trust not later than ten days after the
end of each calendar quarter. The report must include the information with
respect to any transaction in a security effected during the calendar quarter.

5.   Disclaimer of Ownership
     -----------------------

A report may contain a statement that it shall not be construed as an admission
by the person making the report that he has any direct or indirect beneficial
ownership in the reported security.

6.   Submission of Duplicate Confirmations and Periodic Statements
     -------------------------------------------------------------

Each access person (other than a disinterested trustee) must arrange for
duplicate copies of trade confirmations and periodic statements of his brokerage
accounts to be sent to the designated compliance officer for the Trust. This
requirement applies to any brokerage account over which the access person
exercises trading authority other than a brokerage account of a client of an
Adviser over which the access person exercises trading authority in his capacity
as an employee of the Adviser.

K.   CERTIFICATIONS

1.   Certification of Access Persons and Employees of Adviser
     --------------------------------------------------------

Each access person (other than a disinterested trustee) and each employee of an
Adviser will certify annually that:

     (a)  he has read and understood the Code of Ethics and recognizes he is
          subject to its provisions
     (b)  he has complied with the applicable provisions of the Code of Ethics
          and has reported all personal securities transactions required to be
          reported under Section J of the Code.



                                     --8--
<PAGE>   9

2.       Certification of Access Persons
         -------------------------------

In addition to the certification described in paragraph 1 above, each access
person (other than a disinterested trustee) will submit to the Trust:

     (a) a certified list of the title, number of shares and principal amount of
all securities in which he has any direct or indirect beneficial ownership no
later than ten days after he becomes an access person and annually thereafter,
and

     (b) the name of any broker, dealer or bank with whom the Access Person
maintains an account in which any securities are held for the direct or indirect
benefit of the Access Person.

L.   SANCTIONS

The Board of Trustees of the Trust may impose sanctions it deems appropriate
upon any person who violates the Code of Ethics. In addition, the Board of
Trustees of the Trust may impose sanctions it deems appropriate upon any person
who has engaged in a course of conduct that, although in technical compliance
with the Code of Ethics, is part of a plan or scheme to evade the provisions of
the Code of Ethics. Sanctions may include a letter of censure, suspension of
employment, termination of employment, fines, and disgorgement of profits from
prohibited or restricted transactions.


                                     --9--
<PAGE>   10

                                THE GATEWAY TRUST
                                -----------------

                                 CODE OF ETHICS
                                 --------------



I ________________________________have read and agree to abide by the
       (Signature)
Gateway Trust Code of Ethics dated January 25, 2000.




                                     Dated this ____day of _______________, 20__



                                     --10--


<PAGE>   1
                                                                  Exhibit (p)(2)

                        GATEWAY INVESTMENT ADVISERS, L.P.

                                 CODE OF ETHICS
                               (FEBRUARY 28, 2000)

This Code of Ethics is based on the principle that every director, officer, and
employee of Gateway Investment Advisers, L.P. should place the interests of each
client of the Adviser before his own personal interests at all times. Each
director, officer, and employee of the Adviser should avoid any actual or
potential conflicts of interest with any client of the Adviser in all personal
securities transactions. Each director, officer, and employee of the Adviser
should comply with the provisions of the Code of Ethics in all his personal
securities transactions.

A.   DEFINITIONS

1.   "Adviser" means Gateway Investment Advisers, L.P., an Ohio corporation
     registered under the Investment Advisers Act of 1940.

2.   "Client" means any person or entity for which the Adviser acts as an
     investment adviser.

3.   "Access person" means any director or officer of the Adviser or any
     "advisory person" of a client.

4.   "Advisory person" of a means:

     (a)  any employee of an Adviser (or of any company in a control
          relationship to an Adviser) who, in connection with his regular
          functions or duties, obtains information regarding the purchase or
          sale of a security by the
     (b)  any natural person in a control relationship to the Adviser who
          obtains information concerning recommendations made to the client with
          regard to the purchase or sale of a security
     (c)  any "investment representative" of a client.

5.   "Investment representative" of a client means:

     (a)  any portfolio manager of the client
     (b)  any employee of an Adviser (or of any company in a control
          relationship to an Adviser) who, in connection with his regular


                                     --1--
<PAGE>   2

          functions or duties, makes, participates in, or executes the purchase
          or sale of a security by the client
     (c)  any employee of an Adviser (or of any company in a control
          relationship to an Adviser) whose functions relate to the making of
          any recommendations with respect to the purchase or sale of a security
          by the client.

6.   A security is "being considered for purchase or sale" when a recommendation
     to purchase or sell a security has been made and communicated and, with
     respect to the person making the recommendation, when such person seriously
     considers making such a recommendation. Serious consideration includes the
     act of writing a trade ticket, entering an order with a broker, and time
     stamping the trade ticket.

7.   "Beneficial ownership" will be interpreted in the same manner as it would
     be in determining whether a person is subject to the provisions of Section
     16 of the Securities Exchange Act of 1934 and the rules and regulations
     thereunder, except that the determination of direct or indirect beneficial
     ownership shall apply to all securities which an access person has or
     acquires. For purposes of this Code, "Beneficial ownership" includes, but
     is not limited to, securities held by members of a person's immediate
     family sharing the same household and securities over which a person has
     discretionary authority outside of his ordinary course of business.

8.   "Control" has the same meaning as set forth in Section 2(a)(19) of the
     Investment Company Act.

9.   "Purchase or sale of a security" includes the writing of an option to
     purchase or sell a security.

10.  "Security" has the same meaning as set forth in Section 2(a)(36) of the
     Investment Company Act, except that it does not include the following
     securities (the "Excluded Securities"):

     (a)  shares of registered open-end investment companies
     (b)  securities issued by the United States government
     (c)  short-term debt securities that are "government securities" within the
          meaning of Section 2(a)(16) of the Investment Company Act
     (d)  bankers' acceptances
     (e)  bank certificates of deposit
     (f)  commercial paper

                                     --2--
<PAGE>   3

     (g)  such other money market instruments as designated by the Adviser's
          Board of Directors.

A person does not become an "advisory person" or an "investment representative"
simply by virtue of the following activities:

     (a)  normally assisting in the preparation of public reports, or receiving
          public reports, but not receiving information about current
          recommendations or trading; or
     (b)  a single instance of obtaining knowledge of current recommendations or
          trading activity, or infrequently or inadvertently obtaining such
          knowledge.

B.   PROHIBITED PURCHASES AND SALES OF SECURITIES

1.   Prohibited Transactions of Investment Representatives
     -----------------------------------------------------

     (a)  An investment representative of a client may not purchase or sell,
          directly or indirectly, any security (in which he has, or by reason of
          such transaction acquires, any direct or indirect beneficial
          ownership) if the client has a pending buy or sell order in the same
          security until the client's order is executed or withdrawn.

     (b)  An investment representative of a client may not purchase or sell,
          directly or indirectly, any security (in which he has, or by reason of
          such transaction acquires, any direct or indirect beneficial
          ownership) if such security is being considered for purchase or sale
          by the client.

     (c)  An investment representative of a client may not purchase or sell,
          directly or indirectly, any security (in which he has, or by reason of
          such transaction acquires, any direct or indirect beneficial
          ownership) within seven calendar days before or after the execution of
          a trade in the same security by the client.

     (d)  An investment representative of a Fund may not purchase or sell,
          directly or indirectly, any index option contract (in which he has, or
          by reason of such transaction acquires, any direct or indirect
          beneficial ownership).


                                     --3--
<PAGE>   4


2.   Prohibited Transactions of Access Persons
     -----------------------------------------

     (a)  An access person may not purchase or sell, directly or indirectly, any
          security (in which he has, or by reason of such transaction acquires,
          any direct or indirect beneficial ownership) if, to his actual
          knowledge, any client has a pending buy or sell order in the same
          security until the client's order is executed or withdrawn.

     (b)  An access person may not purchase or sell, directly or indirectly, any
          security (in which he has, or by reason of such transaction acquires,
          any direct or indirect beneficial ownership) if, to his actual
          knowledge, such security is being considered for purchase or sale by
          any client.

3.   Prohibited Transactions of Employees of the Adviser
     ---------------------------------------------------

     An employee of the Adviser may not purchase or sell, directly or
     indirectly, any index option contract.

C.   PRECLEARANCE OF SECURITIES TRANSACTIONS

Each access person must obtain approval from a designated compliance officer for
the Adviser prior to purchasing or selling any security, the purchase or sale of
which is not prohibited pursuant to Section B of this Code. Approval will be
valid for two trading days.

D.       EXEMPTED TRANSACTIONS

The prohibitions described in Section B of this Code and the preclearance
requirements set forth in Section C of this Code do not apply to the following
transactions:

     (a)  purchases or sales of Excluded Securities
     (b)  purchases or sales of securities involving less than 2,000 shares of a
          security included in the Standard & Poor's 500 Index
     (c)  purchases or sales of securities involving less than 2,000 shares of a
          security of a company with a market capitalization in excess of $200
          million and average daily trading volume in excess of 50,000 shares
     (d)  purchases or sales of option contracts involving less than 20
          contracts on a security included in the Standard & Poor's 500 Index


                                     --4--
<PAGE>   5

     (e)  purchases or sales of option contracts involving less than 20
          contracts on a security of a company with a market capitalization in
          excess of $200 million and average daily trading volume in excess of
          50,000 shares
     (f)  purchases or sales of securities effected in any account over which
          the access person has no direct or indirect influence or control
     (g)  purchases or sales of securities by an access person that are not
          eligible for purchase or sale by any client
     (h)  purchases or sales of securities that are nonvolitional on the part of
          either the client or the access person
     (i)  purchases of securities that are part of an automatic dividend
          reinvestment plan
     (j)  purchase of securities effected upon the exercise of rights issued by
          an issuer pro rata to all holders of a class of its securities, to the
          extent such rights were acquired from such issuer, or sales of such
          rights.

E.   RESTRICTIONS ON INVESTMENTS IN INITIAL PUBLIC OFFERINGS

An investment representative may not acquire any securities in an initial public
offering without express prior approval from the Adviser.

F.   RESTRICTIONS ON PRIVATE PLACEMENT TRANSACTIONS

An investment representative may not acquire any security of any issuer in a
private placement without express prior approval from the Adviser. An investment
representative of a client must disclose his investment in such security if he
takes part in the Adviser's subsequent decision to recommend or purchase any
security of the issuer for the client.

G.   RESTRICTIONS ON SHORT TERM TRADES

An investment representative may not profit from the purchase and sale, or sale
and purchase, of the same or equivalent securities within 60 calendar days
("short-term trade"). This restriction does not apply to the following
short-term trades:

     (a)  a short-term trade involving Excluded Securities
     (b)  a short-term trade for which express prior approval has been received
          from the Adviser by the investment representative
     (c)  a short-term trade involving no more than 100 shares of a security
          included in the Standard & Poor's 500 Index


                                     --5--
<PAGE>   6

     (d)  a short-term trade involving no more than 100 shares of a security of
          a company with a market capitalization in excess of $200 million and
          average daily trading volume in excess of 50,000 shares
     (e)  a short-term trade involving no more than two option contracts on a
          security included in the Standard & Poor's 500 Index
     (f)  a short-term trade involving no more than two option contracts on a
          security of a company with a market capitalization in excess of $200
          million and average daily trading volume in excess of 50,000 shares
     (g)  a short- term trade in any account over which the investment
          representative has no direct or indirect influence or control
     (h)  a short-term trade that is nonvolitional on the part of the investment
          representative
     (i)  a short-term trade resulting from an automatic dividend reinvestment
           plan.

H.   RESTRICTIONS ON SERVING ON BOARD OF DIRECTORS

An investment representative may not serve on the Board of Directors of a
publicly traded company without express prior approval from the Adviser.

I.   RESTRICTIONS ON ACCEPTANCE OF GIFTS

Neither an access person nor an employee of an Adviser may accept in any
calendar year gifts with a value of more than $100 from any person ("donor")
that does business with or on behalf of the Adviser. Neither an access person
nor an employee of an Adviser may accept in any calendar year gifts with a value
of more than $100 from any donor if, to his actual knowledge, the donor does
business with or on behalf any client. These restrictions do not apply to gifts
in the form of an occasional meal, a ticket to a sporting event, theater or
comparable entertainment, or an invitation to golf or participate in similar
sporting activities for such person and his guests so long as (1) such gifts are
neither so frequent nor so extensive as to raise any question of propriety and
(2) such gifts are not preconditioned on the donor obtaining or maintaining a
specified level of business with the Adviser or any client.

J.   REPORTING

1.   Reports of Access Persons and Employees of Adviser

Each access person (other than a member of the Board of Directors who is not
employed by the Adviser) and each employee of an Adviser must report to the


                                     --6--
<PAGE>   7

Adviser the information described in paragraph 2 below for each transaction in
any security including Excluded Securities (in which he has, or by reason of
such transaction, acquires, any direct or indirect beneficial ownership in the
security). This reporting requirement does not apply to access persons and
employee transactions listed in Items D(a),(f) and (g) under Exempted
Transactions.

2.   Form of Reports
     ---------------

Every report must contain the following information:

     (a)  the date of the transaction
     (b)  the title and number of shares (or the principal amount) of the
          security
     (c)  the nature of the transaction (purchase, sale or other type of
          acquisition or disposition)
     (d)  the price at which the transaction was effected
     (e)  the name of the broker, dealer, bank or other entity through or with
          whom the transaction was effected.

3.   Submission of Reports
     ---------------------

Every report must be submitted to the Adviser not later than ten days after the
end of each calendar quarter. The report must include the information with
respect to any transaction in a security effected during the calendar quarter.

4.   Disclaimer of Ownership
     -----------------------

A report may contain a statement that it shall not be construed as an admission
by the person making the report that he has any direct or indirect beneficial
ownership in the reported security.

5.   Submission of Duplicate Confirmations and Periodic Statements
     -------------------------------------------------------------

Each access person must arrange for duplicate copies of trade confirmations and
periodic statements of his brokerage accounts to be sent to the designated
compliance officer for the Adviser. This requirement applies to any brokerage
account over which the access person exercises trading authority other than a
brokerage account of a client over which the access person exercises trading
authority in his capacity as an employee of the Adviser.



                                     --7--
<PAGE>   8

K.   CERTIFICATIONS

1.   Certification of Access Persons and Employees of Adviser
     --------------------------------------------------------

Each access person (other than a member of the Board of Directors who is not
employed by the Adviser) and each employee of an Adviser will certify annually
that:

     (a)  he has read and understood the Code of Ethics and recognizes he is
          subject to its provisions
     (b)  he has complied with the applicable provisions of the Code of Ethics
          and has reported all personal securities transactions required to be
          reported under Section J of the Code.

2.   Certification of Access Persons
     -------------------------------

In addition to the certification described in paragraph 1 above, each access
person (other than a member of the Board of Directors who is not employed by the
Adviser) will submit to the Adviser no later then ten days after he becomes an
access person and annually therafter:

     (a)  a certified list of the title, number of shares and principal amount
          of all securities in which he/she has any direct or indirect
          beneficial ownership , and
     (b)  the name of any broker, dealer or bank with whom the Access Person
          maintains an account in which any securities are held for the direct
          or indirect benefit of the Access Person.

L.   SANCTIONS

The Board of Directors of the Adviser may impose sanctions it deems appropriate
upon any person who violates the Code of Ethics. In addition, the Board of
Directors of the Adviser may impose sanctions it deems appropriate upon any
person who has engaged in a course of conduct that, although in technical
compliance with the Code of Ethics, is part of a plan or scheme to evade the
provisions of the Code of Ethics. Sanctions may include a letter of censure,
suspension of employment, termination of employment, fines, and disgorgement of
profits from prohibited or restricted transactions.


                                     --8--
<PAGE>   9




                   CERTIFICATION OF RECEIPT OF CODE OF ETHICS
                                       OF
                        GATEWAY INVESTMENT ADVISERS, L.P.


The undersigned employee of Gateway Investment Advisers, L.P. hereby certifies
that he/she has received a copy of the document entitled "Gateway Investment
Advisers, L.P. Code of Ethics" dated February 28, 2000.


- ------------------                                   ---------------------------
Date                                                 Signature


                                     --9--



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