SHORT TERM INVESTMENTS TRUST
497, 1999-12-21
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<PAGE>   1
        TREASURY PORTFOLIO

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

        CASH MANAGEMENT CLASS
        Treasury Portfolio seeks to maximize current income consistent with the
        preservation of capital and the maintenance of liquidity.

        PROSPECTUS
        DECEMBER 17, 1999

                                       This prospectus contains important
                                       information about the Cash
                                       Management Class of the fund. Please
                                       read it before investing and keep it
                                       for future reference.

                                       As with all other mutual fund
                                       securities, the Securities and
                                       Exchange Commission has not approved
                                       or disapproved these securities or
                                       determined whether the information
                                       in this prospectus is adequate or
                                       accurate. Anyone who tells you
                                       otherwise is committing a crime.

                                       There can be no assurance that the
                                       fund will be able to maintain a
                                       stable net asset value of $1.00 per
                                       share.

        [AIM LOGO APPEARS HERE]                  INVEST WITH DISCIPLINE
                                                --Registered Trademark--
<PAGE>   2
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

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

<TABLE>
<S>                                       <C>

INVESTMENT OBJECTIVE AND STRATEGIES           1

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

PRINCIPAL RISKS OF INVESTING IN THE
  FUND                                        1

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

PERFORMANCE INFORMATION                       2

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

Annual Total Returns                          2

Performance Table                             2

FEE TABLE AND EXPENSE EXAMPLE                 3

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

Fee Table                                     3

Expense Example                               3

FUND MANAGEMENT                               4

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

The Advisor                                   4

Advisor Compensation                          4

OTHER INFORMATION                             4

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

Suitability for Investors                     4

Dividends and Distributions                   4

FINANCIAL HIGHLIGHTS                          5

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

SHAREHOLDER INFORMATION                     A-1

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

Distribution and Service (12b-1) Fees       A-1

Purchasing Shares                           A-1

Redeeming Shares                            A-1

Pricing of Shares                           A-2

Taxes                                       A-2

OBTAINING ADDITIONAL INFORMATION     Back Cover

- - - - - - - - - - - - - - - - - - - - - - - - - -
</TABLE>

The AIM Family of Funds, The AIM Family of Funds and Design (i.e., the AIM
logo), AIM and Design, AIM, AIM LINK, AIM Institutional Funds, aimfunds.com, La
Familia AIM de Fondos, La Familia AIM de Fondos and Design and Invest with
Discipline are registered service marks and AIM Bank Connection, AIM Funds, AIM
Funds and Design, AIM Internet Connect and AIM Investor are service marks of
A I M Management Group Inc.

No dealer, salesperson or any other person has been authorized to give any
information or to make any representations other than those contained in this
prospectus, and you should not rely on such other information or
representations.
<PAGE>   3
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

INVESTMENT OBJECTIVE AND STRATEGIES
- --------------------------------------------------------------------------------

The fund's investment objective is to maximize current income consistent with
the preservation of capital and the maintenance of liquidity.

  The fund attempts to meet this objective by investing in direct obligations of
the U.S. Treasury, including bills, notes and bonds, and repurchase agreements
secured by those obligations. The fund will maintain a weighted average maturity
of 90 days or less. The fund invests in compliance with Rule 2a-7 under the
Investment Company Act of 1940.

  The portfolio managers focus on securities they believe have favorable
prospects for current income consistent with the preservation of capital and the
maintenance of liquidity. The portfolio managers usually hold portfolio
securities to maturity, but may sell a particular security when they deem it
advisable, such as when any of the factors above materially changes.

  In anticipation of or in response to adverse market conditions, for cash
management purposes, or for defensive purposes, the fund may temporarily hold
all or a portion of its assets in cash or shares of affiliated money market
funds. As a result, the fund may not achieve its investment objective.

PRINCIPAL RISKS OF INVESTING IN THE FUND
- --------------------------------------------------------------------------------

An investment in the fund is not a deposit of a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. Although the fund seeks to preserve the value of your investment at
$1.00 per share, it is possible to lose money by investing in the fund.
Additionally, the fund's yield will vary as the short-term securities in its
portfolio mature and the proceeds are reinvested in securities with different
interest rates.

  The following factors could reduce the fund's income and/or share price:

- - sharply rising interest rates; and

- - downgrades of credit ratings or defaults of any of the fund's holdings.

  If the seller of a repurchase agreement in which the fund invests defaults on
its obligation or declares bankruptcy, the fund may experience delays in selling
the securities underlying the repurchase agreement. As a result, the fund may
incur losses arising from decline in the value of those securities, reduced
levels of income and expenses of enforcing its rights.

  The value of your shares could be adversely affected if the computer systems
used by the fund's investment advisor and the fund's other service providers are
unable to distinguish the year 2000 from the year 1900.

  The fund's investment advisor and independent technology consultants are
working to avoid year 2000-related problems in its systems and to obtain
assurances that other service providers are taking similar steps. Year 2000
problems may also affect issuers in whose securities the fund invests.

                                        1
<PAGE>   4
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
The bar chart and table shown below provide an indication of the risks of
investing in the fund. The fund's past performance is not necessarily an
indication of its future performance.

ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
The following bar chart shows changes in the performance of the Cash Management
Class shares from year to year. Cash Management Class shares are not subject to
sales loads.

                                    [GRAPH]

<TABLE>
<CAPTION>
                                          Annual
Year Ended                                Total
December 31                               Return
- -----------                               ------
<S>                                       <C>
1994....................................  4.07%
1995....................................  5.86%
1996....................................  5.32%
1997....................................  5.48%
1998....................................  5.39%
</TABLE>

The Cash Management Class shares' year-to-date total return as of September 30,
1999 was 3.58%.

  During the periods shown in the bar chart, the highest quarterly return was
1.47% (quarter ended June 30, 1995) and the lowest quarterly return was 0.78%
(quarter ended March 31, 1994).

PERFORMANCE TABLE

The following performance table reflects the performance of Cash Management
Class shares over the periods indicated.

<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS
- ------------------------------------------------------------------------------------------------------
(for the periods ended                                                          SINCE      INCEPTION
December 31, 1998)                               1 YEAR   5 YEARS   10 YEARS   INCEPTION     DATE
- ------------------------------------------------------------------------------------------------------
<S>                                              <C>      <C>       <C>        <C>         <C>
Cash Management Class                             5.39%    5.22%       --        5.08%      08/18/93
- ------------------------------------------------------------------------------------------------------
</TABLE>

Cash Management Class shares' seven-day yield on December 31, 1998 was 4.73%.
For the current seven-day yield, call (800) 877-7745.

                                        2
<PAGE>   5
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FEE TABLE AND EXPENSE EXAMPLE
- --------------------------------------------------------------------------------

FEE TABLE

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

<TABLE>
<CAPTION>
SHAREHOLDER FEES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(fees paid directly from
your investment)         CASH MANAGEMENT CLASS
- ----------------------------------------------
<S>                      <C>
Maximum Sales Charge (Load)
Imposed on Purchases
(as a percentage of
offering price)                    None

Maximum Deferred
Sales Charge (Load)
(as a percentage of
original purchase
price or redemption
proceeds, whichever is
less)                              None
- ----------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(expenses that are deducted
from fund assets)        CASH MANAGEMENT CLASS
- ----------------------------------------------
<S>                      <C>
Management Fees                   0.06%
Distribution and/or
Service (12b-1) Fees              0.10
Other Expenses                    0.03
Total Annual Fund
Operating Expenses                0.19
Fee Waiver(1)                     0.02
Net Expenses                      0.17
- ----------------------------------------------
</TABLE>

(1) The distributor has contractually agreed to waive 0.02% of the Rule 12b-1
    distribution plan fee.
You should also consider the effect of any account fees charged by the financial
institution managing the account.

EXPENSE EXAMPLE

This example is intended to help you compare the costs of investing in the Cash
Management Class of 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 gross operating expenses remain the same. To the extent fees are waived
or expenses are reimbursed, the expenses will be lower. Although your actual
returns and costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
                   1 YEAR   3 YEARS   5 YEARS   10 YEARS
- --------------------------------------------------------
<S>                <C>      <C>       <C>       <C>
Cash Management
Class               $19       $61      $107       $243
- --------------------------------------------------------
</TABLE>

                                        3
<PAGE>   6
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FUND MANAGEMENT
- --------------------------------------------------------------------------------

THE ADVISOR

A I M Advisors, Inc. (the advisor) serves as the fund's investment advisor and
is responsible for its day-to-day management. The advisor is located at 11
Greenway Plaza, Suite 100, Houston, Texas 77046-1173. The advisor supervises all
aspects of the fund's operations and provides investment advisory services to
the fund, including obtaining and evaluating economic, statistical and financial
information to formulate and implement investment programs for the fund.

  The advisor has acted as an investment advisor since its organization in 1976.
Today, the advisor, together with its subsidiaries, advises or manages over 125
investment portfolios, including the fund, encompassing a broad range of
investment objectives.

ADVISOR COMPENSATION

During the fiscal year ended August 31, 1999, the advisor received compensation
of 0.06% of average daily net assets.

OTHER INFORMATION
- --------------------------------------------------------------------------------

SUITABILITY FOR INVESTORS

The Cash Management Class of the fund is intended for use primarily by customers
of banks, certain broker-dealers and other institutions (institutions). It is
expected that the shares of the Cash Management Class may be particularly
suitable investments for corporate cash managers, municipalities or other public
entities. Individuals, corporations, partnerships and other businesses that
maintain qualified accounts at an institution may invest in shares of the Cash
Management Class. Each institution will render administrative support services
to its customers who are the beneficial owners of the shares of the Cash
Management Class. Such services include, among other things, establishment and
maintenance of shareholder accounts and records; assistance in processing
purchase and redemption transactions in shares of the Cash Management Class;
providing periodic statements showing a client's account balance in shares of
the Cash Management Class; distribution of fund proxy statements, annual reports
and other communications to shareholders whose accounts are serviced by the
institution; and such other services as the fund may reasonably request.
Institutions will be required to certify to the fund that they comply with
applicable state law regarding registration as broker-dealers, or that they are
exempt from such registration.

  The Cash Management Class is designed to be a convenient and economical way to
invest in an open-end diversified money market fund. It is anticipated that most
investors will perform their own subaccounting.

  Investors in the Cash Management Class have the opportunity to receive a
somewhat higher yield than might be obtainable through direct investment in
money market instruments, and enjoy the benefits of diversification, economies
of scale and same-day liquidity. Generally, higher interest rates can be
obtained on the purchase of very large blocks of money market instruments. Of
course, any such relative increase in interest rates may be offset to some
extent by the operating expenses of the Cash Management Class.

DIVIDENDS AND DISTRIBUTIONS

The fund expects that its distributions will consist primarily of ordinary
income.

DIVIDENDS

The fund generally declares dividends on each business day and pays dividends
monthly. A business day is any day on which both the Federal Reserve Bank of New
York and The Bank of New York, the fund's custodian, are open for business.

  Dividends are paid on settled shares of the fund as of 5:00 p.m. Eastern time.
Generally, shareholders whose purchase orders have been received by the fund
prior to 5:00 p.m. Eastern time and shareholders whose redemption proceeds have
not been wired to them on any business day are eligible to receive dividends on
that business day. The dividend declared on any day preceding a non-business day
of the fund will include the income accrued on such non-business day. Dividends
and distributions are paid in cash unless the shareholder has elected to have
such dividends and distributions reinvested in the form of additional full and
fractional shares at net asset value.

CAPITAL GAINS DISTRIBUTIONS

The fund generally distributes net realized capital gains (including net
short-term capital gains), if any, annually. The fund does not expect to realize
any long-term capital gains and losses.

                                        4
<PAGE>   7
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand the financial
performance of the Cash Management Class. Certain information reflects financial
results for a single fund share.

  The total returns in the table represent the rate that 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 KPMG LLP, whose report, along with the
fund's financial statements, is included in the fund's annual report, which is
available upon request.

<TABLE>
<CAPTION>
                                                                 CASH MANAGEMENT CLASS
                                                  ---------------------------------------------------
                                                                 YEAR ENDED AUGUST 31,
                                                    1999       1998       1997       1996      1995
- -----------------------------------------------------------------------------------------------------
<S>                                               <C>        <C>        <C>        <C>        <C>
Net asset value, beginning of period              $   1.00   $   1.00   $   1.00   $   1.00   $  1.00
Income from investment operations:
  Net investment income                               0.05       0.05       0.05       0.05      0.05
Less distributions:
  Dividends from net investment income               (0.05)     (0.05)     (0.05)     (0.05)    (0.05)
Net asset value, end of period                    $   1.00   $   1.00   $   1.00   $   1.00   $  1.00
Total return                                          4.89%      5.56%      5.39%      5.48%     5.57%
- -----------------------------------------------------------------------------------------------------
Ratios/supplemental data:
- -----------------------------------------------------------------------------------------------------
Net assets, end of period (000s omitted)          $860,354   $933,791   $829,243   $789,627   $81,219
Ratio of expenses to average net assets(a)            0.17%(b)     0.17%     0.17%     0.17%     0.18%
Ratio of net investment income to average net
  assets(c)                                           4.77%(b)     5.42%     5.25%     5.25%     5.42%
- -----------------------------------------------------------------------------------------------------
</TABLE>

(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.19%, 0.19%, 0.19%, 0.19% and 0.20% for the periods 1999-1995,
    respectively.
(b) Ratios are based on average net assets of $979,097,144.
(c) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.75%, 5.40%, 5.24%, 5.23% and 5.40% for the periods
    1999 -- 1995, respectively.

                                        5
<PAGE>   8
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION
- --------------------------------------------------------------------------------

The fund currently offers six classes of shares all of which share a common
investment objective and portfolio of investments. The six classes differ only
with respect to distribution arrangements for different categories of investors.

DISTRIBUTION AND SERVICE (12b-1) FEES

The fund has adopted a 12b-1 plan with respect to the Cash Management Class that
allows the fund to pay distribution fees to Fund Management Company (the
distributor) for the sale and distribution of its shares and fees for services
provided to shareholders. Because the fund pays these fees out of its assets on
an ongoing basis, over time these fees will increase the cost of your investment
and may cost you more than paying other types of sales charges.

PURCHASING SHARES

The minimum initial investment in the Cash Management Class is $1 million. No
minimum amount is required for subsequent investments in the fund, nor are
minimum balances required.

  Purchase orders will be accepted for execution on the day the order is placed,
provided that the order is properly submitted and received by the transfer agent
prior to 5:00 p.m. Eastern time on a business day of the fund. Purchase orders
received after such time will be processed at the next day's net asset value.
You may purchase shares by submitting an Account Application to the fund's
transfer agent, A I M Fund Services, Inc. (transfer agent) at P.O. Box 4497,
Houston, Texas 77210-4497 prior to your initial purchase of shares. You must
open a fund account through an institution in accordance with procedures
established by such institution. A purchase order is considered received at the
time The Bank of New York receives federal funds (member bank deposits with a
Federal Reserve Bank) for the order, provided the transfer agent has received
notice of the order. Subsequent purchases of shares of the funds may also be
made via AIM LINK--Registered Trademark-- Remote, a personal computer
application software product.

  If you propose to open a fund account with an institution, you should consult
with a representative of such institution to obtain a description of the rules
governing such an account. A statement with regard to your investment in the
Cash Management Class is supplied periodically, and confirmations of all
transactions for your account are provided by the institution promptly upon
request. In addition, proxies, periodic reports and other information from the
institution with regard to your shares of the Cash Management Class will be sent
to you.

  You may place an order for the purchase of shares of the Cash Management Class
with the institution. The institution is responsible for the prompt transmission
of the order to the transfer agent. The fund is normally required to make
immediate settlement in federal funds for portfolio securities purchased.
Accordingly, payment for shares of the Cash Management Class purchased by
institutions on behalf of their clients must be in federal funds. If an order to
purchase shares is paid for other than in federal funds, the order may be
delayed up to two business days while the institution completes the conversion
into federal funds.

REDEEMING SHARES

You may redeem any or all of your shares at the net asset value next determined
after receipt of a redemption request in proper form by the fund. There is no
charge for redemption. Redemption requests with respect to shares of the Cash
Management Class are normally made through your institution.

  You may request a redemption by calling the transfer agent at (800) 877-7745,
or by using AIM LINK--Registered Trademark-- Remote. Payment for redeemed shares
is normally made by Federal Reserve wire to the commercial bank account
designated in your Account Application. You may also request that payment be
made by check. We use reasonable procedures to confirm that instructions
communicated by telephone are genuine and are not liable for telephone
instructions that are reasonably believed to be genuine. Such reasonable
procedures may include recordings of telephone transactions maintained for a
reasonable period of time.

  Payment for redemption orders received prior to 5:00 p.m. Eastern time will
normally be made on the same day. Payment for shares redeemed by mail and
payment for telephone redemptions in amounts of less than $1,000 may be made by
check mailed within seven days after receipt of the redemption request in proper
form. The fund may make payment for telephone redemptions in excess of $1,000 by
check when it is considered to be in the fund's best interest to do so.

  Dividends payable up to the date of redemption on redeemed shares will
normally be paid by wire transfer on the next dividend payment date. However, if
all of the shares in your account are redeemed, you will receive dividends
payable up to the date of redemption with the proceeds of the redemption.

REDEMPTIONS BY THE FUND

If your account has been open at least one year, you have not made an additional
purchase in the account during the past six calendar months, and the value of
your account falls below $500 for three consecutive months due to redemptions or
exchanges (excluding retirement accounts), the fund has the right to redeem the
account after giving you 60 days' prior written notice. You may avoid having
your account redeemed during the notice period by bringing the account value up
to $500.

  If the fund determines that you have not provided a correct Social Security or
other tax ID number on your account application, the fund may, at its
discretion, redeem the account and distribute the proceeds to you.

                                       A-1
<PAGE>   9
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION (continued)
- --------------------------------------------------------------------------------

 THE FUND AND ITS AGENTS RESERVE THE RIGHT AT ANY TIME TO:

  - REJECT OR CANCEL ANY PART OF ANY PURCHASE ORDER;

  - MODIFY ANY TERMS OR CONDITIONS OF PURCHASE OF SHARES OF THE FUND; OR

  - WITHDRAW ALL OR ANY PART OF THE OFFERING MADE BY THIS PROSPECTUS.

PRICING OF SHARES

DETERMINATION OF NET ASSET VALUE

The price of each of the fund's shares is the fund's net asset value per share.
The fund determines the net asset value of its shares as of 5:00 p.m. Eastern
time on each day on which both the Federal Reserve Bank of New York and The Bank
of New York are open for business (business day). The fund values portfolio
securities on the basis of amortized cost, which approximates market value.

TIMING OF ORDERS

The fund prices purchase and redemption orders at the net asset value calculated
after the transfer agent receives an order in good form. If the transfer agent
receives a redemption request on a business day prior to 5:00 p.m. Eastern time,
the fund will normally wire redemption proceeds on that day. If the transfer
agent receives a redemption request after 5:00 p.m. Eastern time on a business
day of the fund, the redemption will be processed at the net asset value next
determined and the fund will normally wire proceeds on the next business day.
Shareholders will accrue dividends until the day the fund wires redemption
proceeds. The fund may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading. The fund
reserves the right to change the time for which purchase and redemption orders
must be submitted to and received by the transfer agent for execution on the
same day on any day when the primary government securities dealers are either
closed for business or close early, or trading in money market securities is
limited due to national holidays.

TAXES

Dividends and distributions received are taxable as ordinary income or long-term
capital gains for federal income tax purposes, whether reinvested in additional
shares or taken in cash. Distributions are taxable at different rates depending
on the length of time the fund holds its assets. Every year, information will be
sent showing the amount of dividends and distributions received from the fund
during the prior year.

  Any long-term or short-term capital gains realized from redemptions of the
fund shares will be subject to federal income tax.

  The foreign, state and local tax consequences of investing in the fund may
differ materially from the federal income tax consequences described above.
Shareholders should consult their tax advisor before investing.

                                       A-2
<PAGE>   10
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

OBTAINING ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------

More information may be obtained free of charge upon request. The Statement of
Additional Information (SAI), a current version of which is on file with the
Securities and Exchange Commission (SEC), contains more details about the fund
and is incorporated by reference into the prospectus (is legally a part of this
prospectus). Annual and semiannual reports to shareholders contain additional
information about the fund's investments. The fund's annual report also
discusses the market conditions and investment strategies that significantly
affected the fund's performance during its last fiscal year.

  If you have questions about this fund, another fund in The AIM Family of
Funds--Registered Trademark-- or your account, or wish to obtain free copies of
the fund's current SAI or annual or semiannual reports, please contact us

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

<TABLE>
<S>                          <C>
BY MAIL:                     A I M Fund Services, Inc.
                             P.O. Box 4497
                             Houston, TX 77210-4497

BY TELEPHONE:                (800) 877-7745

BY E-MAIL:                   [email protected]

ON THE INTERNET:             http://www.aimfunds.com
                             (prospectuses and annual
                             and semiannual reports
                             only)
</TABLE>

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

You also can review and obtain copies of the fund's SAI, reports and other
information at the SEC's Public Reference Room in Washington, DC; on the EDGAR
database on the SEC's Internet website (http://www.sec.gov); or, after paying a
duplication fee, by sending a letter to the SEC's Public Reference Section,
Washington, DC 20549-0102 or by sending an electronic mail request to
[email protected]. Please call the SEC at 1-202-942-8090 for information about
the Public Reference Room.

- -----------------------------------
 Treasury Portfolio
 SEC 1940 Act file number: 811-2729
- -----------------------------------

[AIM LOGO APPEARS HERE]      www.aimfunds.com             INVEST WITH DISCIPLINE
                                                        --Registered Trademark--
<PAGE>   11
        TREASURY PORTFOLIO

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

        INSTITUTIONAL CLASS
        Treasury Portfolio seeks to maximize current income consistent with the
        preservation of capital and the maintenance of liquidity.

        PROSPECTUS
        DECEMBER 17, 1999

                                       This prospectus contains important
                                       information about the Institutional
                                       Class of the fund. Please read it
                                       before investing and keep it for
                                       future reference.

                                       As with all other mutual fund
                                       securities, the Securities and
                                       Exchange Commission has not approved
                                       or disapproved these securities or
                                       determined whether the information
                                       in this prospectus is adequate or
                                       accurate. Anyone who tells you
                                       otherwise is committing a crime.

                                       There can be no assurance that the
                                       fund will be able to maintain a
                                       stable net asset value of $1.00 per
                                       share.


        [AIM LOGO APPEARS HERE]                  INVEST WITH DISCIPLINE
                                                --Registered Trademark--
<PAGE>   12
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

TABLE OF CONTENTS
- --------------------------------------------------------------------------------
<TABLE>
<S>                                       <C>
INVESTMENT OBJECTIVE AND STRATEGIES           1
- - - - - - - - - - - - - - - - - - - - - - - - - -

PRINCIPAL RISKS OF INVESTING IN THE FUND      1
- - - - - - - - - - - - - - - - - - - - - - - - - -

PERFORMANCE INFORMATION                       2
- - - - - - - - - - - - - - - - - - - - - - - - - -

Annual Total Returns                          2

Performance Table                             2

FEE TABLE AND EXPENSE EXAMPLE                 3
- - - - - - - - - - - - - - - - - - - - - - - - - -

Fee Table                                     3

Expense Example                               3

FUND MANAGEMENT                               4
- - - - - - - - - - - - - - - - - - - - - - - - - -

The Advisor                                   4

Advisor Compensation                          4

OTHER INFORMATION                             4
- - - - - - - - - - - - - - - - - - - - - - - - - -

Suitability for Investors                     4

Dividends and Distributions                   4

FINANCIAL HIGHLIGHTS                          5
- - - - - - - - - - - - - - - - - - - - - - - - - -

SHAREHOLDER INFORMATION                     A-1
- - - - - - - - - - - - - - - - - - - - - - - - - -

Purchasing Shares                           A-1

Redeeming Shares                            A-1

Pricing of Shares                           A-1

Taxes                                       A-2

STATEMENT OF ADDITIONAL INFORMATION         B-1
- - - - - - - - - - - - - - - - - - - - - - - - - -

OBTAINING ADDITIONAL INFORMATION     Back Cover
- - - - - - - - - - - - - - - - - - - - - - - - - -
</TABLE>

The AIM Family of Funds, The AIM Family of Funds and Design (i.e., the AIM
logo), AIM and Design, AIM, AIM LINK, AIM Institutional Funds, aimfunds.com, La
Familia AIM de Fondos, La Familia AIM de Fondos and Design and Invest with
Discipline are registered service marks and AIM Bank Connection, AIM Funds, AIM
Funds and Design, AIM Internet Connect and AIM Investor are service marks of
A I M Management Group Inc.

No dealer, salesperson or any other person has been authorized to give any
information or to make any representations other than those contained in this
prospectus, and you should not rely on such other information or
representations.
<PAGE>   13
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

INVESTMENT OBJECTIVE AND STRATEGIES
- --------------------------------------------------------------------------------

The fund's investment objective is to maximize current income consistent with
the preservation of capital and the maintenance of liquidity.

  The fund attempts to meet this objective by investing in direct obligations of
the U.S. Treasury, including bills, notes and bonds, and repurchase agreements
secured by those obligations. The fund will maintain a weighted average maturity
of 90 days or less. The fund invests in compliance with Rule 2a-7 under the
Investment Company Act of 1940.

  The portfolio managers focus on securities they believe have favorable
prospects for current income consistent with the preservation of capital and the
maintenance of liquidity. The portfolio managers usually hold portfolio
securities to maturity, but may sell a particular security when they deem it
advisable, such as when any of the factors above materially changes.

  In anticipation of or in response to adverse market conditions, for cash
management purposes, or for defensive purposes, the fund may temporarily hold
all or a portion of its assets in cash or shares of affiliated money market
funds. As a result, the fund may not achieve its investment objective.

PRINCIPAL RISKS OF INVESTING IN THE FUND
- --------------------------------------------------------------------------------

An investment in the fund is not a deposit of a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. Although the fund seeks to preserve the value of your investment at
$1.00 per share, it is possible to lose money by investing in the fund.
Additionally, the fund's yield will vary as the short-term securities in its
portfolio mature and the proceeds are reinvested in securities with different
interest rates.

  The following factors could reduce the fund's income and/or share price:

- - sharply rising interest rates; and

- - downgrades of credit ratings or defaults of any of the fund's holdings.

  If the seller of a repurchase agreement in which the fund invests defaults on
its obligation or declares bankruptcy, the fund may experience delays in selling
the securities underlying the repurchase agreement. As a result, the fund may
incur losses arising from decline in the value of those securities, reduced
levels of income and expenses of enforcing its rights.

  The value of your shares could be adversely affected if the computer systems
used by the fund's investment advisor and the fund's other service providers are
unable to distinguish the year 2000 from the year 1900.

  The fund's investment advisor and independent technology consultants are
working to avoid year 2000-related problems in its systems and to obtain
assurances that other service providers are taking similar steps. Year 2000
problems may also affect issuers in whose securities the fund invests.


                                        1
<PAGE>   14
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
The bar chart and table shown below provide an indication of the risks of
investing in the fund. The fund's past performance is not necessarily an
indication of its future performance.

ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
The following bar chart shows changes in the performance of the Institutional
Class shares from year to year. Institutional Class shares are not subject to
sales loads.

                                    [GRAPH]

<TABLE>
<CAPTION>
                                        Annual
Year Ended                               Total
December 31                              Return
- -----------                            ---------
<S>                                    <C>
1989 ................................   9.21%
1990 ................................   8.27%
1991 ................................   6.16%
1992 ................................   3.86%
1993 ................................   3.15%
1994 ................................   4.15%
1995 ................................   5.95%
1996 ................................   5.41%
1997 ................................   5.56%
1998 ................................   5.48%
</TABLE>

The Institutional Class shares' year-to-date total return as of September 30,
1999 was 3.64%.

  During the periods shown in the bar chart, the highest quarterly return was
2.32% (quarter ended June 30, 1989) and the lowest quarterly return was 0.77%
(quarter ended June 30, 1993).

PERFORMANCE TABLE

The following performance table reflects the performance of the Institutional
Class shares over the periods indicated.

<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS
- ----------------------------------------------------------------------------------
(for the periods ended                                        SINCE      INCEPTION
December 31, 1998)             1 YEAR   5 YEARS   10 YEARS   INCEPTION     DATE
- ----------------------------------------------------------------------------------
<S>                             <C>      <C>       <C>        <C>         <C>
Institutional Class             5.48%    5.31%      5.71%      6.34%      04/12/84
- ----------------------------------------------------------------------------------
</TABLE>

Institutional Class shares' seven-day yield on December 31, 1998 was 4.81%. For
the current seven-day yield, call (800) 659-1005.


                                        2
<PAGE>   15
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

FEE TABLE AND EXPENSE EXAMPLE
- --------------------------------------------------------------------------------
FEE TABLE

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

<TABLE>
<CAPTION>
SHAREHOLDER FEES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(fees paid directly from
your investment)              INSTITUTIONAL CLASS
- -------------------------------------------------
<S>                           <C>
Maximum Sales Charge (Load)
Imposed on Purchases
(as a percentage of
offering price)                        None

Maximum Deferred
Sales Charge (Load)
(as a percentage of
original purchase
price or redemption
proceeds, whichever is
less)                                  None
- -------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(expenses that are deducted
from fund assets)             INSTITUTIONAL CLASS
- -------------------------------------------------
<S>                           <C>
Management Fees                       0.06%

Distribution and/or
Service (12b-1) Fees                  None

Other Expenses                        0.03

Total Annual Fund
Operating Expenses                    0.09
- -------------------------------------------------
</TABLE>

You should also consider the effect of any account fees charged by the financial
institution managing the account.

EXPENSE EXAMPLE

This example is intended to help you compare the costs of investing in the
Institutional Class of 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 gross operating expenses remain the same. To the extent fees are waived
or expenses are reimbursed, the expenses will be lower. Although your actual
returns and costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
                 1 YEAR   3 YEARS   5 YEARS   10 YEARS
- ------------------------------------------------------
<S>              <C>      <C>       <C>       <C>
Institutional
Class              $9       $29       $51       $115
- ------------------------------------------------------
</TABLE>

                                        3
<PAGE>   16
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------


FUND MANAGEMENT
- --------------------------------------------------------------------------------

THE ADVISOR

A I M Advisors, Inc. (the advisor) serves as the fund's investment advisor and
is responsible for its day-to-day management. The advisor is located at 11
Greenway Plaza, Suite 100, Houston, Texas 77046-1173. The advisor supervises all
aspects of the fund's operations and provides investment advisory services to
the fund, including obtaining and evaluating economic, statistical and financial
information to formulate and implement investment programs for the fund.

  The advisor has acted as an investment advisor since its organization in 1976.
Today, the advisor, together with its subsidiaries, advises or manages over 125
investment portfolios, including the fund, encompassing a broad range of
investment objectives.

ADVISOR COMPENSATION

During the fiscal year ended August 31, 1999, the advisor received compensation
of 0.06% of average daily net assets.

OTHER INFORMATION
- --------------------------------------------------------------------------------

SUITABILITY FOR INVESTORS

The Institutional Class of the fund is intended for use by banks and other
institutions, investing for themselves or in a fiduciary, advisory, agency,
custodial or other similar capacity. Shares of the Institutional Class may not
be purchased directly by individuals, although institutions may purchase the
Institutional Class for accounts maintained for individuals. Prospective
investors should determine if an investment in the Institutional Class is
consistent with the investment objectives of an account and with applicable
state and federal laws and regulations.

  The Institutional Class is designed to be a convenient and economical way to
invest short-term cash reserves in an open-end diversified money market fund. It
is anticipated that most investors will perform their own subaccounting.

  Investors in the Institutional Class have the opportunity to receive a
somewhat higher yield than might be obtainable through direct investment in
money market instruments, and enjoy the benefits of diversification, economies
of scale and same-day liquidity. Generally, higher interest rates can be
obtained on the purchase of very large blocks of money market instruments. Of
course, any such relative increase in interest rates may be offset to some
extent by the operating expenses of the Institutional Class.

DIVIDENDS AND DISTRIBUTIONS

The fund expects that its distributions will consist primarily of ordinary
income.

DIVIDENDS

The fund generally declares dividends on each business day and pays dividends
monthly. A business day is any day on which both the Federal Reserve Bank of New
York and The Bank of New York, the fund's custodian, are open for business.

  Dividends are paid on settled shares of the fund as of 5:00 p.m. Eastern time.
Generally, shareholders whose purchase orders have been received by the fund
prior to 5:00 p.m. Eastern time and shareholders whose redemption proceeds have
not been wired to them on any business day are eligible to receive dividends on
that business day. The dividend declared on any day preceding a non-business day
of the fund will include the income accrued on such non-business day. Dividends
and distributions are paid in cash unless the shareholder has elected to have
such dividends and distributions reinvested in the form of additional full and
fractional shares at net asset value.

CAPITAL GAINS DISTRIBUTIONS

The fund generally distributes net realized capital gains (including net
short-term capital gains), if any, annually. The fund does not expect to realize
any long-term capital gains and losses.


                                        4
<PAGE>   17
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------


FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand the financial
performance of the Institutional Class. Certain information reflects financial
results for a single fund share.

  The total returns in the table represent the rate that 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 KPMG LLP, whose report, along with the
fund's financial statements, is included in the fund's annual report, which is
available upon request.

<TABLE>
<CAPTION>
                                                                                   INSTITUTIONAL CLASS
                                                           -------------------------------------------------------------------
                                                                                  YEAR ENDED AUGUST 31,
                                                                 1999           1998          1997          1996          1995
- ------------------------------------------------------------------------------------------------------------------------------
<S>                                                        <C>            <C>           <C>           <C>           <C>
Net asset value, beginning of period                       $     1.00     $     1.00    $     1.00    $     1.00    $     1.00
Income from investment operations:
  Net investment income                                          0.05           0.05          0.05          0.05          0.06
Less distributions:
  Dividends from net investment income                          (0.05)         (0.05)        (0.05)        (0.05)        (0.06)
Net asset value, end of period                             $     1.00     $     1.00    $     1.00    $     1.00    $     1.00
Total return                                                     4.97%          5.64%         5.47%         5.57%         5.66%
- ------------------------------------------------------------------------------------------------------------------------------
Ratios/supplemental data:
- ------------------------------------------------------------------------------------------------------------------------------
Net assets, end of period (000s omitted)                   $3,164,199     $2,988,375    $3,408,010    $2,335,441    $2,669,637
Ratio of expenses to average net assets                          0.09%(a)       0.08%         0.09%         0.09%         0.10%
Ratio of net investment income to average net assets             4.85%(a)       5.50%         5.35%         5.43%         5.53%
- ------------------------------------------------------------------------------------------------------------------------------
</TABLE>

(a) Ratios are based on average net assets of $3,197,910,489.

                                        5
<PAGE>   18
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------


SHAREHOLDER INFORMATION
- --------------------------------------------------------------------------------

The fund currently offers six classes of shares all of which share a common
investment objective and portfolio of investments. The six classes differ only
with respect to distribution arrangements for different categories of investors.

PURCHASING SHARES

The minimum initial investment in the Institutional Class is $1 million. No
minimum amount is required for subsequent investments in the fund, nor are
minimum balances required.

  Purchase orders will be accepted for execution on the day the order is placed,
provided that the order is properly submitted and received by the transfer agent
prior to 5:00 p.m. Eastern time on a business day of the fund. Purchase orders
received after such time will be processed at the next day's net asset value.
You may purchase shares by submitting an Account Application to the fund's
transfer agent, A I M Fund Services, Inc. (transfer agent) at P.O. Box 4497,
Houston, Texas 77210-4497 prior to your initial purchase of shares. A purchase
order is considered received at the time The Bank of New York receives federal
funds (member bank deposits with a Federal Reserve Bank) for the order, provided
the transfer agent has received notice of the order. Subsequent purchases of
shares of the funds may also be made via AIM LINK--Registered Trademark--
Remote, a personal computer application software product.

  We may request that an institution maintain separate master accounts in the
fund for shares held by the institution (a) for its own account, for the account
of other institutions and for accounts for which the institution acts as a
fiduciary; and (b) for accounts for which the institution acts in some other
capacity. An institution may aggregate its master accounts and subaccounts to
satisfy the minimum investment requirement.

REDEEMING SHARES

You may redeem any or all of your shares at the net asset value next determined
after receipt of a redemption request in proper form by the fund. There is no
charge for redemption.

  You may request a redemption by calling the transfer agent at (800) 659-1005,
or by using AIM LINK--Registered Trademark-- Remote. Payment for redeemed shares
is normally made by Federal Reserve wire to the commercial bank account
designated in your Account Application. You may also request that payment be
made by check. We use reasonable procedures to confirm that instructions
communicated by telephone are genuine and are not liable for telephone
instructions that are reasonably believed to be genuine. Such reasonable
procedures may include recordings of telephone transactions maintained for a
reasonable period of time.

  Payment for redemption orders received prior to 5:00 p.m. Eastern time will
normally be made on the same day. Payment for shares redeemed by mail and
payment for telephone redemptions in amounts of less than $1,000 may be made by
check mailed within seven days after receipt of the redemption request in proper
form. The fund may make payment for telephone redemptions in excess of $1,000 by
check when it is considered to be in the fund's best interest to do so.

  Dividends payable up to the date of redemption on redeemed shares will
normally be paid on the next dividend payment date. However, if all of the
shares in your account are redeemed, you will receive dividends payable up to
the date of redemption with the proceeds of the redemption.

REDEMPTIONS BY THE FUND

If your account has been open at least one year, you have not made an additional
purchase in the account during the past six calendar months, and the value of
your account falls below $500 for three consecutive months due to redemptions or
exchanges (excluding retirement accounts), the fund has the right to redeem the
account after giving you 60 days' prior written notice. You may avoid having
your account redeemed during the notice period by bringing the account value up
to $500.

  If the fund determines that you have not provided a correct Social Security or
other tax ID number on your account application, the fund may, at its
discretion, redeem the account and distribute the proceeds to you.

  THE FUND AND ITS AGENTS RESERVE THE RIGHT AT ANY TIME TO:

  - REJECT OR CANCEL ANY PART OF ANY PURCHASE ORDER;

  - MODIFY ANY TERMS OR CONDITIONS OF PURCHASE OF SHARES OF THE FUND; OR

  - WITHDRAW ALL OR ANY PART OF THE OFFERING MADE BY THIS PROSPECTUS.

PRICING OF SHARES

DETERMINATION OF NET ASSET VALUE

The price of each of the fund's shares is the fund's net asset value per share.
The fund determines the net asset value of its shares as of 5:00 p.m. Eastern
time on each day on which both the Federal Reserve Bank of New York and The Bank
of New York are open for business (business day). The fund values portfolio
securities on the basis of amortized cost, which approximates market value.

TIMING OF ORDERS

The fund prices purchase and redemption orders at the net asset value calculated
after the transfer agent receives an order in good form. If the transfer agent
receives a redemption request on a business day prior to 5:00 p.m. Eastern time,
the fund will normally wire redemption proceeds on that day. If the transfer
agent receives a redemption request after 5:00 p.m. Eastern time on a business
day of the fund, the redemption will be processed at the net asset value next


                                       A-1
<PAGE>   19
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------


SHAREHOLDER INFORMATION (continued)
- --------------------------------------------------------------------------------

determined and the fund will normally wire proceeds on the next business day.
Shareholders will accrue dividends until the day the fund wires redemption
proceeds. The Fund may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading. The fund
reserves the right to change the time for which purchase and redemption orders
must be submitted to and received by the transfer agent for execution on the
same day on any day when the primary government securities dealers are either
closed for business or close early, or trading in money market securities is
limited due to national holidays.

TAXES

Dividends and distributions received by shareholders are taxable as ordinary
income or long-term capital gains for federal income tax purposes, whether
reinvested in additional shares or taken in cash. Distributions are taxable at
different rates depending on the length of time the fund holds its assets. Every
year, information will be sent showing the amount of dividends and distribution
received from the fund during the prior year.

  Any long-term or short-term capital gains realized from redemptions of the
fund shares will be subject to federal income tax.

  The foreign, state and local tax consequences of investing in the fund may
differ materially from the federal income tax consequences described above.
Shareholders should consult their tax advisor before investing.


                                       A-2
<PAGE>   20

                                                     STATEMENT OF
                                                     ADDITIONAL INFORMATION

                          SHORT-TERM INVESTMENTS TRUST

                               TREASURY PORTFOLIO

                            (CASH MANAGEMENT CLASS)

                             (INSTITUTIONAL CLASS)

                          (PERSONAL INVESTMENT CLASS)

                           (PRIVATE INVESTMENT CLASS)

                                (RESERVE CLASS)

                                (RESOURCE CLASS)

                               11 GREENWAY PLAZA
                                   SUITE 100
                           HOUSTON, TEXAS 77046-1173
                                 (800) 659-1005

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

         THIS STATEMENT OF ADDITIONAL INFORMATION IS NOT A PROSPECTUS.
 IT SHOULD BE READ IN CONJUNCTION WITH A PROSPECTUS OF EACH OF THE ABOVE NAMED
                                    CLASSES
     OF THE TREASURY PORTFOLIO, COPIES OF WHICH MAY BE OBTAINED BY WRITING
                  FUND MANAGEMENT COMPANY, 11 GREENWAY PLAZA,
                      SUITE 100, HOUSTON, TEXAS 77046-1173
                           OR CALLING (800) 659-1005

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

          STATEMENT OF ADDITIONAL INFORMATION DATED DECEMBER 17, 1999
  RELATING TO THE PROSPECTUS OF EACH OF THE FOLLOWING CLASSES OF THE TREASURY
                                   PORTFOLIO:
           CASH MANAGEMENT CLASS PROSPECTUS DATED DECEMBER 17, 1999,
            INSTITUTIONAL CLASS PROSPECTUS DATED DECEMBER 17, 1999,
         PERSONAL INVESTMENT CLASS PROSPECTUS DATED DECEMBER 17, 1999,
          PRIVATE INVESTMENT CLASS PROSPECTUS DATED DECEMBER 17, 1999,
                RESERVE CLASS PROSPECTUS DATED DECEMBER 17, 1999
             AND RESOURCE CLASS PROSPECTUS DATED DECEMBER 17, 1999
                                       B-1
<PAGE>   21

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                               PAGE
                                                               -----
<S>                                                            <C>
Introduction................................................     B-4
General Information about the Trust.........................     B-4
     The Trust and Its Shares...............................     B-4
     Trustees and Officers..................................     B-6
     Remuneration of Trustees...............................     B-8
     Investment Advisor.....................................     B-9
     Administrative Services................................    B-10
     Expenses...............................................    B-11
     Transfer Agent and Custodian...........................    B-11
     Legal Matters..........................................    B-11
     Reports................................................    B-12
     Sub-accounting.........................................    B-12
     Principal Holders of Securities........................    B-12
Share Purchases and Redemptions.............................    B-19
     Purchases and Redemptions..............................    B-19
     Redemptions by the Portfolio...........................    B-19
     Net Asset Value Determination..........................    B-19
     Distribution Agreement.................................    B-20
     Distribution Plan......................................    B-20
     Banking Regulations....................................    B-22
     Performance Information................................    B-22
Investment Program and Restrictions.........................    B-23
     Investment Program.....................................    B-23
     Investment Policies....................................    B-24
     Eligible Securities....................................    B-25
     Investment Restrictions................................    B-25
     Other Investment Policies..............................    B-26
Portfolio Transactions and Brokerage........................    B-26
     General Brokerage Policy...............................    B-26
     Allocation of Portfolio Transactions...................    B-27
     Section 28(e) Standards................................    B-27
Dividends, Distributions and Tax Matters....................    B-28
     Dividends and Distributions............................    B-28
     Tax Matters............................................    B-28
     Qualification as a Regulated Investment Company........    B-29
     Excise Tax on Regulated Investment Companies...........    B-29
     Portfolio Distributions................................    B-29
     Sale or Redemption of Shares...........................    B-30
</TABLE>

                                       B-2
<PAGE>   22

<TABLE>
<CAPTION>
                                                               PAGE
                                                               -----
<S>                                                            <C>
Foreign Shareholders........................................    B-30
     Effect of Future Legislation; Local Tax
      Considerations........................................    B-31
Financial Statements........................................      FS
</TABLE>

                                       B-3
<PAGE>   23

                                  INTRODUCTION

  The Treasury Portfolio (the "Portfolio") is an investment portfolio of
Short-Term Investments Trust (the "Trust"), a mutual fund. The rules and
regulations of the United States Securities and Exchange Commission (the "SEC")
require all mutual funds to furnish prospective investors certain information
concerning the activities of the fund being considered for investment. This
information is included in the Cash Management Class Prospectus dated December
17, 1999, the Institutional Class Prospectus dated December 17, 1999, the
Personal Investment Class Prospectus dated December 17, 1999, the Private
Investment Class Prospectus dated December 17, 1999, the Reserve Class
Prospectus dated December 17, 1999 and the Resource Class Prospectus dated
December 17, 1999 (each a "Prospectus"). Additional copies of each Prospectus
and this Statement of Additional Information may be obtained without charge by
writing the principal distributor of the Trust's shares, Fund Management Company
("FMC"), 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173, or by calling
(800) 659-1005. Investors must receive a Prospectus before they invest.

  This Statement of Additional Information is intended to furnish prospective
investors with additional information concerning the Trust and each class of the
Portfolio. Some of the information required to be in this Statement of
Additional Information is also included in each Prospectus; and, in order to
avoid repetition, reference will be made to sections of the applicable
Prospectus. Additionally, each Prospectus and this Statement of Additional
Information omit certain information contained in the registration statement
filed with the SEC. Copies of the registration statement, including items
omitted from each Prospectus and this Statement of Additional Information, may
be obtained from the SEC by paying the charges prescribed under its rules and
regulations.

                      GENERAL INFORMATION ABOUT THE TRUST

THE TRUST AND ITS SHARES

  The Trust is an open-end diversified management series investment company
which was originally organized as a corporation under the laws of the State of
Maryland on January 24, 1977, but which had no operations prior to November 10,
1980. The Trust was reorganized as a business trust under the laws of the
Commonwealth of Massachusetts on December 31, 1986. The Trust was again
reorganized as a business trust under the laws of the State of Delaware on
October 15, 1993. A copy of the Amended and Restated Agreement and Declaration
of Trust (the "Declaration of Trust") establishing the Trust is on file with the
SEC. On October 15, 1993, the Portfolio succeeded to the assets and assumed the
liabilities of the Treasury Portfolio (the "Predecessor Portfolio") of
Short-Term Investments Co., a Massachusetts business trust ("STIC"), pursuant to
an Agreement and Plan of Reorganization between the Trust and STIC. All
historical financial and other information contained in this Statement of
Additional Information for periods prior to October 15, 1993 relating to the
Portfolio (or a class thereof) is that of the Predecessor Portfolio (or the
corresponding class thereof). Shares of beneficial interest of the Trust are
redeemable at the net asset value thereof at the option of the shareholder or at
the option of the Trust in certain circumstances. For information concerning the
methods of redemption and the rights of share ownership, investors should
consult each Prospectus under the caption "Redeeming Shares."

  The Trust offers on a continuous basis shares representing an interest in one
of three portfolios: the Portfolio, the Government & Agency Portfolio and the
Treasury TaxAdvantage Portfolio (together, the "Portfolios"). The Portfolio
consists of the following six classes of shares: Cash Management Class,
Institutional Class, Personal Investment Class, Private Investment Class,
Reserve Class and Resource Class. Each class of shares is sold pursuant to a
separate Prospectus and this joint Statement of Additional Information. Each
such class has different shareholder qualifications and bears expenses
differently. This Statement of Additional Information relates to each class of
the Portfolio. The classes of the Treasury TaxAdvantage Portfolio and the
Government & Agency Portfolio are offered pursuant to separate prospectuses and
separate statements of additional information.

  As used in the Prospectus, the term "majority of the outstanding shares" of
the Trust, a particular portfolio or a particular class means, respectively, the
vote of the lesser of (i) 67% or more of the shares of the Trust, such portfolio
or such class present at a meeting of the Trust's shareholders, if the holders
of more than 50% of the outstanding shares of the Trust, such portfolio or such
class are present or represented by proxy, or (ii) more than 50% of the
outstanding shares of the Trust, such portfolio or such class.

  All shares of the Trust have equal rights with respect to voting, except that
the holders of shares of a particular class will have the exclusive right to
vote on matters pertaining to distribution plans or shareholder service plans,
if any such plans are adopted, relating solely to such class.

  Shareholders of the Trust do not have cumulative voting rights. Therefore the
holders of more than 50% of the outstanding shares of all series or classes
voting together for election of trustees may elect all of the members of the
Board of Trustees and in such event, the remaining holders cannot elect any
members of the Board of Trustees.

                                       B-4
<PAGE>   24

  The Declaration of Trust provides for the perpetual existence of the Trust.
The Trust, any Portfolio and any class thereof, however, may be terminated at
any time, upon the recommendation of the Board of Trustees, by vote of a
majority of the outstanding shares of the Trust, such Portfolio and such class,
respectively; provided, however, that the Board of Trustees may terminate,
without such shareholder approval, the Trust, any Portfolio and any class
thereof with respect to which there are fewer than 100 holders of record.

  There are no preemptive or conversion rights applicable to any of the Trust's
shares. The Trust's shares, when issued, will be fully paid and non-assessable.
Shares are fully assignable and subject to encumbrance by a shareholder. The
Board of Trustees may establish and designate and change in any manner any
portfolio or any classes or classes thereof, may fix or change the preferences,
voting rights, rights and privileges of any portfolio or classes thereof, and
may divide or combine the shares of any portfolio or classes thereof into a
greater or lesser number. The Board of Trustees also may classify or reclassify
or convert any issued shares of any portfolio, or classes thereof, into a
greater or lesser number. Any such classification or reclassification will
comply with the provisions of the Investment Company Act of 1940, as amended
(the "1940 Act").

  The Declaration of Trust permits the trustees to issue an unlimited number of
full and fractional shares, of $.01 par value, of each class of shares of
beneficial interest of the Trust. The Board of Trustees may establish additional
series or classes of shares from time to time without shareholder approval.

  The assets received by the Trust for the issue or sale of shares of each class
relating to a portfolio and all income, earnings, profits, losses and proceeds
therefrom, subject only to the rights of creditors, will be allocated to that
portfolio, and constitute the underlying assets of that portfolio. The
underlying assets of each portfolio will be segregated and will be charged with
the expenses with respect to that portfolio and its respective classes and with
a share of the general expenses of the Trust. While certain expenses of the
Trust will be allocated to the separate books of account of each portfolio,
certain other expenses may be legally chargeable against the assets of the
entire Trust.

  Under Delaware law, shareholders of a Delaware business trust shall be
entitled to the same limitations of liability extended to shareholders of
private for-profit corporations, however, there is a remote possibility that
shareholders could, under certain circumstances, be held liable for the
obligations of the Trust to the extent the courts of another state which does
not recognize such limited liability were to apply the laws of such state to a
controversy involving such obligations. However, the Declaration of Trust
disclaims shareholder liability for acts or obligations of the Trust and
requires that notice of such disclaimer be given in each agreement, obligation
or instrument entered into or executed by the Trust or the trustees to all
parties, and each party thereto must expressly waive all rights of action
directly against shareholders of the Trust. The Declaration of Trust provides
for indemnification out of the property of the Portfolio for all losses and
expenses of any shareholder of the Portfolio held liable on account of being or
having been a shareholder. Thus, the risk of a shareholder incurring financial
loss due to shareholder liability is limited to circumstances in which the
Portfolio would be unable to meet its obligations and wherein the complaining
party was held not to be bound by the disclaimer.

  The Declaration of Trust further provides that the trustees and officers will
not be personally liable for any act, omission or obligation of the Trust or any
Trustee of officer. However, nothing in the Declaration of Trust protects a
trustee or officer against any liability to the Trust or to the shareholders to
which a trustee or officer would otherwise be subject by reason of willful
misfeasance, bad faith, gross negligence, or reckless disregard of the duties
involved in the conduct of his office with the Trust. The Declaration of Trust
provides for indemnification by the Trust of the trustees, the officers,
employees or agents of the Trust, if it is determined that such person acted in
good faith and reasonably believed: (1) in the case of conduct in his official
capacity for the Trust, that his conduct was in the Trust's best interests, (2)
in all other cases, that his conduct was at least not opposed to the Trust's
best interests and (3) in a criminal proceeding, that he had no reason to
believe that his conduct was unlawful. Such person may not be indemnified
against any liability to the Trust or to the Trust's shareholders to which he
would otherwise be subject by reason of willful misfeasance, bad faith, gross
negligence or reckless disregard of the duties involved in the conduct of his
office. The Declaration of Trust also authorizes the purchase of liability
insurance on behalf of trustees and officers.

  As described in the Prospectus, the Trust will not normally hold annual
shareholders' meetings. At such time as less than a majority of the trustees
have been elected by the shareholders, the trustees then in office will call a
shareholders' meeting for the election of trustees. In addition, trustees may be
removed from office by a written consent signed by the holders of two-thirds of
the outstanding shares of the Trust and filed with the Trust's custodian or by a
vote of the holders of two-thirds of the outstanding shares at a meeting duly
called for that purpose, which meeting shall be held upon written request of the
holders of not less than 10% of the outstanding shares of the Trust.

  Except as otherwise disclosed in each Prospectus and this Statement of
Additional Information, the trustees shall continue to hold office and may
appoint their successors.

                                       B-5
<PAGE>   25

  The overall management of the business and affairs of the Trust is vested with
its Board of Trustees. The Board of Trustees approves all significant agreements
between the Trust and persons or companies furnishing services to the Trust,
including agreements with the Trust's investment advisor, distributor, custodian
and transfer agent. The day-to-day operations of the Trust are delegated to the
Trust's officers and to A I M Advisors, Inc. ("AIM"), subject always to the
objective and policies of the Trust and to the general supervision of the
Trust's Board of Trustees. Certain trustees and officers of the Trust are
affiliated with AIM and A I M Management Group Inc. ("AIM Management"), the
parent corporation of AIM.

TRUSTEES AND OFFICERS

  The trustees and officers of the Trust and their principal occupations during
at least the last five years are set forth below. Unless otherwise indicated,
the address of each trustee and officer is 11 Greenway Plaza, Suite 100,
Houston, Texas 77046.

<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------------------------
                                        POSITIONS HELD
         NAME, ADDRESS AND AGE          WITH REGISTRANT      PRINCIPAL OCCUPATION DURING AT LEAST THE PAST 5 YEARS
<S>  <C>                                <C>                  <C>                                                    <C>
- -----------------------------------------------------------------------------------------------------------------------
     *CHARLES T. BAUER (80)              Trustee and         Chairman of the Board of Directors, A I M Management
                                           Chairman          Group Inc., A I M Advisors, Inc., A I M Capital
                                                             Management, Inc., A I M Distributors, Inc., A I M
                                                             Fund Services, Inc. and Fund Management Company; and
                                                             Executive Vice Chairman and Director, AMVESCAP PLC.
- -----------------------------------------------------------------------------------------------------------------------
     BRUCE L. CROCKETT (55)                Trustee           Director, ACE Limited (insurance company). Formerly,
     906 Frome Lane                                          Director, President and Chief Executive Officer,
     McLean, VA 22102                                        COMSAT Corporation; and Chairman, Board of Governors
                                                             of INTELSAT (international communications company).
- -----------------------------------------------------------------------------------------------------------------------
     OWEN DALY II (75)                     Trustee           Director, Cortland Trust Inc. (investment company).
     Six Blythewood Road                                     Formerly, Director, CF & I Steel Corp., Monumental
     Baltimore, MD 21210                                     Life Insurance Company and Monumental General
                                                             Insurance Company; and Chairman of the Board of
                                                             Equitable Bancorporation.
- -----------------------------------------------------------------------------------------------------------------------
     EDWARD K. DUNN, JR. (64)              Trustee           Chairman of the Board of Directors, Mercantile
     2 Hopkins Plaza, 8th Floor                              Mortgage Corp. Formerly, Vice Chairman of the Board
     Suite 805                                               of Directors, President and Chief Operating Officer,
     Baltimore, MD 21201                                     Mercantile-Safe Deposit & Trust Co., and President,
                                                             Mercantile Bankshares.
- -----------------------------------------------------------------------------------------------------------------------
     JACK M. FIELDS (47)                   Trustee           Chief Executive Officer, Texana Global, Inc. (foreign
     8810 Will Clayton Parkway                               trading company) and Twenty First Century Group, Inc.
     Jetero Plaza, Suite E                                   (a governmental affairs company). Formerly, Member of
     Humble, TX 77338                                        the U.S. House of Representatives.
- -----------------------------------------------------------------------------------------------------------------------
     **CARL FRISCHLING (62)                Trustee           Partner, Kramer Levin Naftalis & Frankel, LLP (law
     919 Third Avenue                                        firm).
     New York, NY 10022
- -----------------------------------------------------------------------------------------------------------------------
     *ROBERT H. GRAHAM (53)              Trustee and         Director, President and Chief Executive Officer,
                                          President          A I M Management Group Inc.; Director and President,
                                                             A I M Advisors, Inc.; and Director and Senior Vice
                                                             President, A I M Capital Management, Inc., A I M
                                                             Distributors, Inc., A I M Fund Services, Inc. and
                                                             Fund Management Company; and Director, AMVESCAP PLC.
- -----------------------------------------------------------------------------------------------------------------------
</TABLE>

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

 * A trustee who is an "interested person" of the Trust and AIM as defined in
   the 1940 Act.

** A trustee who is an "interested person" of the Trust as defined in the 1940
   Act.

                                       B-6
<PAGE>   26

<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------------------------------------
                                        POSITIONS HELD
         NAME, ADDRESS AND AGE          WITH REGISTRANT      PRINCIPAL OCCUPATION DURING AT LEAST THE PAST 5 YEARS
<S>  <C>                                <C>                  <C>                                                    <C>
- -----------------------------------------------------------------------------------------------------------------------
     PREMA MATHAI-DAVIS (49)               Trustee           Chief Executive Officer, YWCA of the U.S.A.
     350 Fifth Avenue, Suite 301
     New York, NY 10118
- -----------------------------------------------------------------------------------------------------------------------
     LEWIS F. PENNOCK (57)                 Trustee           Partner, Pennock & Cooper (law firm).
     6363 Woodway, Suite 825
     Houston, TX 77057
- -----------------------------------------------------------------------------------------------------------------------
     LOUIS S. SKLAR (60)                   Trustee           Executive Vice President, Development and Operations,
     The Williams Tower,                                     Hines Interests Limited Partnership (real estate
       50th Floor                                            development).
     2800 Post Oak Blvd.
     Houston, TX 77056
- -----------------------------------------------------------------------------------------------------------------------
     GARY T. CRUM (52)                   Senior Vice         Director and President, A I M Capital Management,
                                          President          Inc.; Director and Executive Vice President, A I M
                                                             Management Group Inc.; Director and Senior Vice
                                                             President, A I M Advisors, Inc.; and
                                                             Director, A I M Distributors, Inc. and AMVESCAP PLC.
- -----------------------------------------------------------------------------------------------------------------------
     CAROL F. RELIHAN (45)               Senior Vice         Director, Senior Vice President, General Counsel and
                                        President and        Secretary, A I M Advisors, Inc.; Senior Vice
                                          Secretary          President, General Counsel and Secretary, A I M
                                                             Management Group Inc.; Director, Vice President and
                                                             General Counsel, Fund Management Company; General
                                                             Counsel and Vice President, A I M Fund Services,
                                                             Inc.; and Vice President, A I M Capital Management,
                                                             Inc. and A I M Distributors, Inc.
- -----------------------------------------------------------------------------------------------------------------------
     DANA R. SUTTON (40)                Vice President       Vice President and Fund Controller, A I M Advisors,
                                        and Treasurer        Inc.; and Assistant Vice President and Assistant
                                                             Treasurer, Fund Management Company.
- -----------------------------------------------------------------------------------------------------------------------
     MELVILLE B. COX (56)               Vice President       Vice President and Chief Compliance Officer, A I M
                                                             Advisors, Inc., A I M Capital Management, Inc., A I M
                                                             Distributors, Inc., A I M Fund Services, Inc. and
                                                             Fund Management Company.
- -----------------------------------------------------------------------------------------------------------------------
     KAREN DUNN KELLEY (39)             Vice President       Senior Vice President, A I M Capital Management,
                                                             Inc.; and Vice President, A I M Advisors, Inc.
- -----------------------------------------------------------------------------------------------------------------------
     J. ABBOTT SPRAGUE (44)             Vice President       Director and President, Fund Management Company;
                                                             Director, A I M Fund Services, Inc.; and Senior Vice
                                                             President, A I M Advisors, Inc. and A I M Management
                                                             Group Inc.
- -----------------------------------------------------------------------------------------------------------------------
</TABLE>

  The standing committees of the Board of Trustees are the Audit Committee, the
Investments Committee, and the Nominating and Compensation Committee.

  The members of the Audit Committee are Messrs. Crockett, Daly, Dunn
(Chairman), Fields, Frischling, Pennock, Sklar and Dr. Mathai-Davis. The Audit
Committee is responsible for meeting with the Trust's auditors to review audit
procedures and results and to consider any matters arising from an audit to be
brought to the attention of the trustees as a whole with respect to the Trust's
fund accounting or its internal accounting controls, or for considering such
matters as may from time to time be set forth in a charter adopted by the Board
of Trustees and such committee.

  The members of the Investments Committee are Messrs. Bauer, Crockett, Daly,
Dunn, Fields, Frischling, Pennock, Sklar (Chairman) and Dr. Mathai-Davis. The
Investments Committee is responsible for reviewing portfolio compliance,
brokerage allocation, portfolio investment pricing issues, interim dividend and
distribution issues, or considering such matters as may from time to time be set
forth in a charter adopted by the Board of Trustees and such committee.


                                       B-7
<PAGE>   27

  The members of the Nominating and Compensation Committee are Messrs. Crockett
(Chairman), Daly, Dunn, Fields, Pennock, Sklar and Dr. Mathai-Davis. The
Nominating and Compensation Committee is responsible for considering and
nominating individuals to stand for election as trustees who are not interested
persons as long as the Trust maintains a distribution plan pursuant to Rule
12b-1 under the 1940 Act, reviewing from time to time the compensation payable
to the disinterested trustees, or considering such matters as may from time to
time be set forth in a charter adopted by the Board of Trustees and such
committee.

  All of the Trust's trustees also serve as directors or trustees of some or all
of the other investment companies managed or advised by AIM. All of the Trust's
executive officers hold similar offices with some or all of such investment
companies.

REMUNERATION OF TRUSTEES

  Each trustee is reimbursed for expenses incurred in connection with each
meeting of the Board of Trustees or any committee thereof. Each trustee who is
not an officer of the Trust is compensated for his or her services according to
a fee schedule which recognizes the fact that such trustee also serves as a
director or trustee of certain other regulated investment companies managed,
administered or distributed by AIM or its affiliates (the "AIM Funds"). Each
such trustee receives a fee, allocated among the AIM Funds for which he or she
serves as a director or trustee, which consists of an annual retainer component
and a meeting fee component.

  Set forth below is information regarding compensation paid or accrued for each
trustee of the Trust:

<TABLE>
<CAPTION>
                                                                       RETIREMENT
                                                     AGGREGATE          BENEFITS           TOTAL
                                                    COMPENSATION        ACCRUED         COMPENSATION
                                                        FROM             BY ALL           FROM ALL
                     TRUSTEE                          TRUST(1)        AIM FUNDS(2)      AIM FUNDS(3)
                     -------                        ------------      ------------      ------------
<S>                                                 <C>               <C>               <C>
Charles T. Bauer..................................     $    0           $      0           $     0
Bruce L. Crockett.................................      5,724             37,485            96,000
Owen Daly II......................................      5,724            122,898            96,000
Edward K. Dunn, Jr................................      5,724                  0            78,889
Jack Fields.......................................      5,695             15,826            95,500
Carl Frischling(4)................................      5,694             97,791            95,500
Robert H. Graham..................................          0                  0                 0
John F. Kroeger(5)................................        506            107,896            91,654
Prema Mathai-Davis................................      5,344                  0            32,636
Lewis F. Pennock..................................      5,694             45,766            95,500
Ian W. Robinson(6)................................      3,551             94,442            94,500
Louis S. Sklar....................................      5,694             90,232            95,500
</TABLE>

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

(1) The total amount of compensation deferred by all trustees of the Trust
    during the fiscal year ended August 31, 1999, including interest earned
    thereon, was $36,280.

(2) During the fiscal year ended August 31, 1999, the total amount of expenses
    allocated to the Trust in respect of such retirement benefits was $35,554.
    Data reflects compensation for the calendar year ended December 31, 1998.

(3) Each trustee serves as a director or trustee of a total of 12 registered
    investment companies advised by AIM (comprised of over 50 portfolios). Data
    reflects total compensation for the calendar year ended December 31, 1998.

(4) The Trust paid the law firm of Kramer Levin Naftalis & Frankel $13,465 in
    legal fees for services provided to the Portfolio during the fiscal year
    ended August 31, 1999. Mr. Frischling, a trustee of the Trust, is a partner
    in such firm.

(5) Mr. Kroeger was a trustee until June 11, 1998, when he resigned. On that
    date, he became a consultant to the Trust. Of the amount listed above, $0
    was for compensation for services as a trustee and the remainder as a
    consultant. Mr. Kroeger passed away on November 26, 1998. Mr. Kroeger's
    widow will receive his pension as described below under "AIM Funds
    Retirement Plan for Eligible Directors/Trustees."

(6) Mr. Robinson was a trustee until March 12, 1999, when he retired.

                                       B-8
<PAGE>   28

  AIM Funds Retirement Plan for Eligible Directors/Trustees

  Under the terms of the AIM Funds Retirement Plan for Eligible
Directors/Trustees (the "Plan"), each trustee (who is not an employee of any of
the AIM Funds, AIM Management or any of their affiliates) may be entitled to
certain benefits upon retirement from the Board of Trustees. Pursuant to the
Plan, the normal retirement date is the date on which the eligible trustee has
attained age 65 and has completed at least five years of continuous service with
one or more of the regulated investment companies managed, administered or
distributed by AIM or its affiliates (the "Applicable AIM Funds"). Each eligible
trustee is entitled to receive an annual benefit from the Applicable AIM Funds
commencing on the first day of the calendar quarter coincident with or following
his date of retirement equal to a maximum of 75% of the annual retainer paid or
accrued by the Applicable AIM Funds for such trustee during the twelve-month
period immediately preceding the trustee's retirement (including amounts
deferred under a separate agreement between the Applicable AIM Funds and the
trustee) and based on the number of such trustee's years of service (not in
excess of 10 years of service) completed with respect to any of the Applicable
AIM Funds. Such benefit is payable to each eligible trustee in quarterly
installments. If an eligible trustee dies after attaining the normal retirement
date but before receipt of any benefits under the Plan commences, the trustee's
surviving spouse (if any) shall receive a quarterly survivor's benefit equal to
50% of the amount payable to the deceased trustee, for no more than ten years
beginning the first day of the calendar quarter following the date of the
trustee's death. Payments under the Plan are not secured or funded by any
Applicable AIM Fund.

  Set forth below is a table that shows the estimated annual benefits payable to
an eligible trustee upon retirement assuming a specified level of compensation
and years of service classifications. The estimated credited years of service
for Messrs. Crockett, Daly, Dunn, Fields, Frischling, Kroeger, Pennock,
Robinson, Sklar and Dr. Mathai-Davis are 12, 12, 1, 2, 22, 20, 18, 11, 10 and 1
years, respectively.

                        ANNUAL RETAINER UPON RETIREMENT

<TABLE>
<CAPTION>
     NUMBER OF YEARS OF          ANNUAL RETIREMENT
        SERVICE WITH          COMPENSATION PAID BY ALL
    APPLICABLE AIM FUNDS        APPLICABLE AIM FUNDS
    --------------------      ------------------------
<S>                           <C>
10..........................          $67,500
 9..........................          $60,750
 8..........................          $54,000
 7..........................          $47,250
 6..........................          $40,500
 5..........................          $33,750
</TABLE>

  Deferred Compensation Agreements

  Messrs. Daly, Dunn, Fields, Frischling, Robinson and Sklar (for purposes of
this paragraph only, the "deferring trustees") have each executed a Deferred
Compensation Agreement (collectively, the "Agreements"). Pursuant to the
Agreements, the deferring trustees may elect to defer receipt of up to 100% of
their compensation payable by the Trust, and such amounts are placed into a
deferral account. Currently, the deferring trustees may select various AIM Funds
in which all or part of their deferral accounts shall be deemed to be invested.
Distributions from the deferring trustees' deferral accounts will be paid in
cash, generally in equal quarterly installments over a period of five (5) or ten
(10) years (depending on the Agreement) beginning on the date the deferring
trustee's retirement benefits commence under the Plan. The Trust's Board of
Trustees, in its sole discretion, may accelerate or extend the distribution of
such deferral accounts after the deferring trustee's termination of service as a
trustee of the Trust. If a deferring trustee dies prior to the distribution of
amounts in his deferral account, the balance of the deferral account will be
distributed to his designated beneficiary in a single lump sum payment as soon
as practicable after such deferring trustee's death. The Agreements are not
funded and, with respect to the payments of amounts held in the deferral
accounts, the deferring trustees have the status of unsecured creditors of the
Trust and of each other AIM Fund from which they are deferring compensation.

  During the fiscal year ended August 31, 1999, $51,955 in trustees' fees and
expenses were allocated to the Portfolio.

INVESTMENT ADVISOR

  AIM is a wholly owned subsidiary of AIM Management, a holding company that has
been engaged in the financial services business since 1976. The address of AIM
is 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173. AIM together with
its subsidiaries advises or manages over 125 investment portfolios encompassing
a broad range of investment objectives. AIM Management is an indirect wholly
owned subsidiary of AMVESCAP PLC, 11 Devonshire Square, London EC2M 4YR, United
Kingdom. AMVESCAP PLC and its subsidiaries are an independent investment
management group engaged in institutional investment management and retail fund
businesses in the United States, Europe and the Pacific Region. Certain of the

                                       B-9
<PAGE>   29

directors and officers of AIM are also executive officers of the Trust and their
affiliations are shown under "Trustees and Officers." The address of each
director and officer of AIM is 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173.

  FMC is a registered broker-dealer and wholly owned subsidiary of AIM. FMC acts
as distributor of the shares of the Portfolio.

  AIM and the Trust have adopted a Code of Ethics which requires investment
personnel (a) to pre-clear all personal securities transactions subject to the
Code of Ethics, (b) to file reports regarding such transactions, (c) to refrain
from personally engaging in (i) short-term trading of a security, (ii)
transactions involving a security within seven days of an AIM Fund transaction
involving the same security, and (iii) transactions involving securities being
considered for investment by an AIM Fund, and (d) to abide by certain other
provisions under the Code of Ethics. The Code of Ethics also prohibits
investment personnel and all other AIM employees from purchasing securities in
an initial public offering. Personal trading reports are reviewed periodically
by AIM, and the Board of Trustees reviews quarterly and annual reports
(including information on any substantial violations of the Code of Ethics).
Sanctions for violations of the Code of Ethics may include censure, monetary
penalties, suspension or termination of employment.

  The Trust has entered into a Master Investment Advisory Agreement (the
"Advisory Agreement") with AIM. The Advisory Agreement will continue from year
to year provided that it is specifically approved at least annually by the
Trust's Board of Trustees and the affirmative vote of a majority of the trustees
who are not parties to the Advisory Agreement or "interested persons" of any
such party by votes cast in person at a meeting called for such purpose. The
Trust or AIM may terminate the Advisory Agreement on 60 days' notice without
penalty. The Advisory Agreement terminates automatically in the event of its
assignment, as defined in the 1940 Act.

  Pursuant to the terms of the Advisory Agreement, AIM manages the investment of
the Portfolio's assets and obtains and evaluates economic, statistical and
financial information to formulate and implement investment policies for the
Portfolio. Any investment program undertaken by AIM will at all times be subject
to the policies and control of the Trust's Board of Trustees. AIM shall not be
liable to the Trust or to its shareholders for any act or omission by AIM or for
any loss sustained by the Trust or its shareholders except in the case of
willful misfeasance, bad faith, gross negligence or reckless disregard of duty.

  As compensation for its services with respect to the Portfolio, AIM receives a
monthly fee which is calculated by applying the following annual rates to the
average daily net assets of the Portfolio:

<TABLE>
<CAPTION>
                         NET ASSETS                           RATE
                         ----------                           ----
<S>                                                           <C>
First $300 million..........................................    .15%
Over $300 million to $1.5 billion...........................    .06%
Over $1.5 billion...........................................    .05%
</TABLE>

  Pursuant to the Advisory Agreement between the Trust and AIM currently in
effect and under an investment advisory agreement in effect prior to February
28, 1997 which provided for the same level of compensation to AIM, AIM received
fees from the Trust for the fiscal years ended August 31, 1999, 1998 and 1997,
with respect to the Portfolio in the amounts of $3,072,316, $3,026,608 and
$2,666,379, respectively. For the fiscal years ended August 31, 1999, 1998 and
1997, AIM waived no advisory fees with respect to the Portfolio.

  AIM may from time to time waive or reduce its fee. Voluntary fee waivers or
reductions may be rescinded at any time without further notice to investors.
During periods of voluntary fee waivers or reductions, AIM will retain its
ability to be reimbursed for such fee prior to the end of each fiscal year.
Contractual fee waivers or reductions set forth in the Fee Table in a Prospectus
may not be terminated or amended to the Portfolio's detriment during the period
stated in the agreement between AIM and the Trust.

  The Advisory Agreement provides that, upon the request of the Board of
Trustees, AIM may perform or arrange for the performance of certain additional
services on behalf of the Portfolio which are not required by the Advisory
Agreement. AIM may receive reimbursement or reasonable compensation for such
additional services, as may be agreed upon by AIM and the Board of Trustees,
based upon a finding by the Board of Trustees that the provision of such
services would be in the best interest of the Portfolio and its shareholders.
The Board of Trustees has made such a finding and, accordingly, has entered into
a Master Administrative Services Agreement under which AIM will provide the
additional services described below under the caption "Administrative Services."

ADMINISTRATIVE SERVICES

  AIM also acts as the Portfolio's administrator pursuant to a Master
Administrative Services Agreement between AIM and the Trust (the "Administrative
Services Agreement").

                                      B-10
<PAGE>   30

  Under the Administrative Services Agreement, AIM performs, or arranges for the
performance of, accounting and other administrative services for the Portfolio.
As full compensation for the performance of such services, AIM is reimbursed for
any personnel and other costs (including applicable office space, facilities and
equipment) of furnishing the services of a principal financial officer of the
Trust and of persons working under his supervision for maintaining the financial
accounts and books and records of the Trust, including calculation of the
Portfolio's daily net asset value, and preparing tax returns and financial
statements for the Portfolio. The method of calculating such reimbursements must
be annually approved, and the amounts paid will be periodically reviewed, by the
Trust's Board of Trustees.

  For the fiscal years ended August 31, 1999, 1998 and 1997, under the
Administrative Services Agreement and under a prior administrative services
agreement which provided for the same level of reimbursement to AIM, AIM was
reimbursed $179,471, $102,543 and $99,273, respectively, for fund accounting
services for the Portfolio.

EXPENSES

  In addition to fees paid to AIM pursuant to the Advisory Agreement and the
expenses reimbursed to AIM under the Administrative Services Agreement, the
Trust also pays or causes to be paid all other expenses of the Trust, including,
without limitation: the charges and expenses of any registrar, any custodian or
depository appointed by the Trust for the safekeeping of its cash, portfolio
securities and other property, and any transfer, dividend or accounting agent or
agents appointed by the Trust; brokers' commissions chargeable to the Trust in
connection with portfolio securities transactions to which the Trust is a party;
all taxes, including securities issuance and transfer taxes, and fees payable by
the Trust to federal, state or other governmental agencies; the costs and
expenses of engraving or printing of certificates representing shares of the
Trust; all costs and expenses in connection with the registration and
maintenance of registration of the Trust and its shares with the SEC and various
states and other jurisdictions (including filing and legal fees and
disbursements of counsel); the costs and expenses of printing, including
typesetting, and distributing prospectuses and statements of additional
information of the Trust and supplements thereto to the Trust's shareholders;
all expenses of shareholders' and trustees' meetings and of preparing, printing
and mailing of prospectuses, proxy statements and reports to shareholders; fees
and travel expenses of trustees and trustee members of any advisory board or
committee; all expenses incident to the payment of any dividend, distribution,
withdrawal or redemption, whether in shares or in cash; charges and expenses of
any outside service used for pricing of the Trust's shares; charges and expenses
of legal counsel, including counsel to the trustees of the Trust who are not
"interested persons" (as defined in the 1940 Act) of the Trust or AIM, and of
independent accountants in connection with any matter relating to the Trust;
membership dues of industry associations; interest payable on Trust borrowings;
postage; insurance premiums on property or personnel (including officers and
trustees) of the Trust which inure to its benefit; and extraordinary expenses
(including, but not limited to, legal claims and liabilities and litigation
costs and any indemnification related thereto). FMC bears the expenses of
printing and distributing prospectuses and statements of additional information
(other than those prospectuses and statements of additional information
distributed to existing shareholders of the Trust) and any other promotional or
sales literature used by FMC or furnished by FMC to purchasers or dealers in
connection with the public offering of the Trust's shares.

  Expenses of the Trust which are not directly attributable to the operations of
any class of shares or portfolio of the Trust are prorated among all classes of
the Trust. Expenses of the Trust except those listed in the next sentence are
prorated among all classes of such Portfolio. Distribution and service fees,
transfer agency fees and shareholder recordkeeping fees which are directly
attributable to a specific class of shares are charged against the income
available for distribution as dividends to the holders of such shares.

TRANSFER AGENT AND CUSTODIAN

  A I M Fund Services, Inc.("AFS"), a wholly owned subsidiary of AIM, P.O. Box
4497, Houston, Texas 77210-4497, acts as transfer agent for the shares of each
class of the Portfolio pursuant to a Transfer Agency and Service Agreement. For
the services it provides to the Trust, AFS is entitled to receive a fee based on
the average daily net assets of the Trust, plus out-of-pocket expenses and
advances it has incurred. Such compensation may be changed from time to time as
is agreed to by AFS and the Trust.

  The Bank of New York ("BONY") acts as custodian for the portfolio securities
and cash of the Portfolio. BONY receives such compensation from the Trust for
its services in such capacity as is agreed to from time to time by BONY and the
Trust. The address of BONY is 90 Washington Street, 11th Floor, New York, New
York 10286.

LEGAL MATTERS

  The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania serves as counsel to the Trust.

                                      B-11
<PAGE>   31

REPORTS

  The Trust furnishes shareholders with semi-annual reports containing
information about the Trust and its operations, including a schedule of
investments held in the Portfolio and its financial statements. The annual
financial statements are audited by the Trust's independent auditors. The Board
of Trustees has selected KPMG LLP, 700 Louisiana, Houston, Texas 77002, as the
independent auditors to audit the financial statements and review the tax
returns of the Portfolio.

SUB-ACCOUNTING

  The Trust and FMC have arranged for AFS or the Portfolio to offer
sub-accounting services to shareholders of the Portfolio and to maintain
information with respect to the underlying beneficial ownership of the shares of
each class of the Portfolio. Investors who purchase shares of the Portfolio for
the account of others can make arrangements through the Trust or FMC for these
sub-accounting services. In addition, shareholders utilizing certain versions of
AIM LINK--Registered Trademark-- Remote, a personal computer application
software product, may receive sub-accounting services via such software.

PRINCIPAL HOLDERS OF SECURITIES

GOVERNMENT & AGENCY PORTFOLIO

  To the best of the knowledge of the Trust, the names and addresses of the
holders of 5% or more of the outstanding shares of each class of the Government
& Agency Portfolio as of November 1, 1999, and the percentage of such shares
owned by such shareholders as of such date are as follows:

CASH MANAGEMENT CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
Fund Services Associates, Inc. .............................       44.67%         --
     1875 Century Park East -- Suite 1345
     Los Angeles, CA 90067
  Orlando-Orange Co. 40700..................................       31.01%         --
     225 Water Street, 3rd Floor
     P.O. Box 44204
     Jacksonville, FL 32202
  Cruttendon Roth, Incorporated.............................        7.06%         --
     24 Corporate Plaza
     Newport Beach, CA 92660
  Gardnyr Michael Capital, Inc..............................        6.68%         --
     2281 Lee Rd. Ste. 104
     Winter Park, FL 32789
</TABLE>

INSTITUTIONAL CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
AIM Fund of Funds Account...................................       42.22%(b)      --
     Money Market Portfolio Admin.
     11 Greenway Plaza, Ste. 100
     Houston, TX
  Gardnyr Michael Capital, Inc. ............................       24.45%         --
     2281 Lee Rd. Ste. 104
     Winter Park, FL 32789
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

(b) A shareholder who holds more than 25% of the outstanding shares of a
    portfolio may be presumed to be in "control" of such portfolio, as defined
    in the 1940 Act.

                                      B-12
<PAGE>   32

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
Waukesha County.............................................        8.36%         --
     Finance Division, Dept. of Admin.
     1320 Pewaukee Road, Room 310
     Waukesha, WI 53188-3878
</TABLE>

PRIVATE INVESTMENT CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
Fund Services Associates, Inc...............................       78.47%         --
     1875 Century Park East -- Suite 1345
     Los Angeles, CA 90067
  Huntington Capital Corp...................................       17.21%         --
     41 S. High St., Ninth Floor
     Columbus, OH 43287
</TABLE>

RESOURCE CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
Kansas City Power & Light...................................      76.73%            --
     P.O. Box 418679
     Kansas City, MO 64106

  Craigie Incorporated......................................      12.08%            --
     P.O. Box 29715
     Richmond, VA 23242

  Hambrecht & Quist LLC.....................................       8.47%            --
     230 Park Avenue, Floor 19
     New York, NY 10169
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

                                      B-13
<PAGE>   33

TREASURY PORTFOLIO

  To the best of the knowledge of the Trust, the names and addresses of the
holders of 5% or more of the outstanding shares of each class of the Treasury
Portfolio as of November 1, 1999 and the percentage of such shares owned by such
shareholders as of such date are as follows:

CASH MANAGEMENT CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  Bank of New York..........................................      36.16%            --
     One Wall Street
     5th Floor
     Stif/Master Note
     New York, NY 10286
  Bank of Oklahoma..........................................      12.46%            --
     P.O. Box 2180
     Tulsa, OK 74101
  Chase Bank of Texas.......................................      12.10%            --
     600 Travis St., 8th Fl
     8-CBT-39
     Houston, TX 77252-8009
  CIBC World Markets........................................      11.11%            --
     200 Liberty Street
     World Financial Center
     New York, NY 10281
  Fund Services Associates, Inc.............................       7.91%            --
     1875 Century Park East - Suite 1345
     Los Angeles, CA 90067
  Huntington Capital Corp...................................       6.18%            --
     41 S. High St., Ninth Floor
     Columbus, OH 43287
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

                                      B-14
<PAGE>   34

INSTITUTIONAL CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  City of New York Deferred Compensation Plan...............       8.23%            --
     40 Rector Street, 3rd Floor
     New York, NY 10006
  Trust Company Bank........................................       7.22%
     Center 3139
     P.O. Box 105504
     Atlanta, GA 30348
  Weststar Bank Trust Dept..................................       5.67%            --
     P.O. Box 1156
     Bartlesville, OK 74005-1156
  Trustmark National Bank, Trust Department.................       5.37%            --
     248 East Capitol
     Jackson, MS 39205
  Turtle & Co Sweep.........................................       5.14%            --
     P.O. Box 9427
     Boston, MA 02209
  Texas Commerce Bank National Association, as Custo........       5.04%            --
     1585 Broadway
     New York, NY 10036
  Chase Bank of Texas, National Association.................       5.04%            --
     600 Travis, 9th Floor
     Houston, TX 77002
</TABLE>

PERSONAL INVESTMENT CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  Cullen/Frost Discount Brokers.............................      83.98%            --
     P.O. Box 2358
     San Antonio, TX 78299
  Kinco & Co c/o Rnb Securities.............................       7.50%            --
     1 Hanson Pl., Lower Level
     Brooklyn, NY 11243
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

                                      B-15
<PAGE>   35

PRIVATE INVESTMENT CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  Bank of New York..........................................      40.73%              --
     One Wall Street
     5th Floor
     Stif/Master Note
     New York, NY 10286
  Huntington Capital Corp...................................      17.70%              --
     41 S. High St., Ninth Floor
     Columbus, OH 43287
  Strafe & Co...............................................       6.24%              --
     1111 Polaris Parkway
     Columbus, OH 43271-0211
  New Haven Savings Bank Trust Department...................       5.58%              --
     P.O. Box 302
     Trust Department
     New Haven, CT 06502
  Zions First National Bank (NV)............................       5.39%              --
     P.O. Box 30880
     Salt Lake City, UT 84130
</TABLE>

RESERVE CLASS

<TABLE>
<CAPTION>
                                                                                  PERCENT
                                                                 PERCENT           OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  Bank of New York..........................................      99.83%              --
    440 Mamoroneck, 5th Fl.
    Harrison, NY 10286
</TABLE>

RESOURCE CLASS

<TABLE>
<CAPTION>
                                                                                  PERCENT
                                                                 PERCENT           OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
First Union Subaccounts.....................................      65.49%              --
    8739 Research Drive
    Capital Markets
    Charlotte, NC 28262-0675
  Mellon Bank NA............................................      13.12%              --
    P.O. Box 710
    Pittsburgh, PA 15230-0710
  CIBC World Markets........................................      10.08%              --
    200 Liberty Street
    World Financial Center
    New York, NY 10281
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

                                      B-16
<PAGE>   36

TREASURY TAXADVANTAGE PORTFOLIO

  To the best of the knowledge of the Trust, the names and addresses of the
holders of 5% or more of the outstanding shares of each class of the Treasury
TaxAdvantage Portfolio as of November 1, 1999 and the percentage of such shares
owned by such shareholders as of such date are as follows:

INSTITUTIONAL CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  Frost National Bank Tx....................................      14.43%            --
     Muir & Co
     C/O Frost
     P.O. Box 2479
     San Antonio, TX 78298-2479
  First Trust/Var & Co......................................      14.36%            --
     Funds Control Suite 0404
     180 East Fifth Street
     St. Paul, MN 55101
  Bank of America N.A.......................................      13.38%            --
     1401 Elm Street 11th Floor
     P.O. Box 831000
     Dallas, TX 75202-2911
  Key Trust Company.........................................      12.07%            --
     Mail Code OH-01-49-3040
     P.O. Box 94871
     Cleveland, OH 44101-5971
  Kanaly Trust Company......................................      10.79%            --
     4550 Post Oak Place Drive
     Suite 139
     Houston, TX 77027
  Mason-Dixon Trust Company.................................      10.27%            --
     45 W. Main Street
     Westminster, MD 21158-0199
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

                                      B-17
<PAGE>   37

PRIVATE INVESTMENT CLASS

<TABLE>
<CAPTION>
                                                                 PERCENT       PERCENT OWNED
                      NAME AND ADDRESS                           OWNED OF      OF RECORD AND
                      OF RECORD OWNER                         RECORD ONLY(a)   BENEFICIALLY
                      ----------------                        --------------   -------------
<S>                                                           <C>              <C>
  Bank of New York..........................................      32.25%            --
     One Wall Street
     5th Floor
     Stif/Master Note
     New York, NY 10286
  Frost National Bank Tx....................................      21.35%            --
     Muir & Co
     C/O Frost
     P.O. Box 2479
     San Antonio, TX 78298-2479
  Huntington Capital Corp...................................      20.65%            --
     41 S. High St., Ninth Floor
     Columbus, OH 43287
  First Union Securities, Inc...............................      19.39%            --
     8739 Research Drive
     Capital Markets
     Charlotte, NC 28262-0675
</TABLE>

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

(a) The Trust has no knowledge as to whether all or any portion of the shares
    owned of record only are also owned beneficially.

  To the best of the knowledge of the Trust, as of November 1, 1999, the
trustees and officers of the Trust as a group beneficially owned less than 1% of
each class of the Trust's outstanding shares.

                                      B-18
<PAGE>   38

                        SHARE PURCHASES AND REDEMPTIONS

PURCHASES AND REDEMPTIONS

  A complete description of the manner by which shares of a particular class may
be purchased or redeemed appears in each Prospectus under the headings
"Purchasing Shares" and "Redeeming Shares."

  Prior to the initial purchase of Portfolio shares, an investor must complete
and send an Account Application to AFS at P.O. Box 4497, Houston, Texas
77210-4497. An Account Application may be obtained from the distributor. An
investor may make changes to the information provided in the Account Application
by submitting such changes in writing to the transfer agent or by completing and
submitting to the transfer agent a new Account Application.

  The Trust reserves the right to reject any purchase order and to withdraw all
or any part of the offering made by a Prospectus. Any funds received with
respect to an order which is not accepted by the Trust and any funds received
for which an order has not been received will be promptly returned to an
investor. Any request for correction to a transaction of Portfolio shares must
be submitted in writing to AFS. AFS reserves the right to reject any such
request. When a correction results in a dividend adjustment, the institution
must agree in writing to reimburse the Portfolio for any loss resulting from the
correction. Failure to deliver purchase proceeds on the requested settlement
date may result in a claim against the institution for an amount equal to the
overdraft charge incurred by the Portfolio.

  An investor may terminate his relationship with an institution at any time, in
which case an account in the investor's name will be established directly with
the Portfolio and the investor will become a shareholder of record. In such
case, however, the investor will not be able to purchase additional shares of
the Cash Management Class, Personal Investment Class, Private Investment Class,
Reserve Class or the Resource Class directly, except through reinvestment of
dividends and distributions.

  Payment for redeemed shares of the Portfolio is normally made by Federal
Reserve wire to the commercial bank account designated in the shareholder's
Account Application on the day specified below, but may be remitted by check
upon request by a shareholder. A shareholder may change the bank account
designated to receive redemption proceeds by written notice to the Trust. The
authorized signature on the notice must be guaranteed by a commercial bank or
trust company (which may include the shareholder). Additional documentation may
be required when deemed appropriate by the Portfolio or AFS.

  The Trust may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading.

  A "Business Day" of the Trust is any day on which member banks of the Federal
Reserve Bank of New York and The Bank of New York are open for business.
However, the Trust will be closed for business on December 24, 1999. If AFS
receives a redemption request on a Business Day prior to 5:00 p.m. Eastern time,
the redemption will be effected at the net asset value of the Portfolio
determined as of 5:00 p.m. Eastern time and the Trust will normally wire
redemption proceeds on that day. A redemption request received by AFS after 5:00
p.m. Eastern time will be effected at the net asset value of the Portfolio
determined as of 5:00 p.m. Eastern time on the next Business Day and proceeds
will normally be wired on the next Business Day. If proceeds are not wired on
the same day, shareholders will accrue dividends until the day the proceeds are
wired. The Trust, however, reserves the right to change the time for which
purchase and redemption orders must be submitted to and received by the transfer
agent for execution on the same day on any day when the primary government
securities dealers are either closed for business or close early, or trading in
money market securities is limited due to national holidays.

  Any request for correction to a redemption transaction of Portfolio shares
must be submitted in writing to AFS.

REDEMPTIONS BY THE PORTFOLIO

  If the Trust determines that you have provided incorrect information in
opening an account or in the course of conducting subsequent transactions, the
Trust may, at its discretion, redeem the account and distribute the proceeds to
you.

  The Board of Trustees may redeem shares if it determines in its sole
discretion that failure to so redeem may have materially adverse consequences to
the shareholders of the Portfolio.

NET ASSET VALUE DETERMINATION

  The net asset value per share of the Portfolio is determined as of 5:00 p.m.
Eastern time on each Business Day of the Trust. For the purpose of determining
the price at which all shares of the Portfolio are issued and redeemed, the net
asset value per share is calculated by: (a) valuing all securities and
instruments of the Portfolio as set forth below; (b) adding other assets of the
Portfolio, if any; (c) deducting the liabilities of the Portfolio; (d) dividing
the resulting amount by the number of shares outstanding of the Portfolio; and
(e) rounding such per share net asset value to the nearest whole cent. Among
other items, the

                                      B-19
<PAGE>   39

Portfolio's liabilities include accrued expenses and dividends payable, and its
total assets include portfolio securities valued at their market value as well
as income accrued but not yet received.

  The debt instruments held in the Portfolio are valued on the basis of
amortized cost. This method involves valuing an instrument at its cost and
thereafter assuming a constant amortization to maturity of any discount or
premium, regardless of the impact of fluctuating interest rates on the market
value of the instrument. While this method provides certainty in valuation, it
may result in periods during which value, as determined by amortized cost, is
higher or lower than the price the Trust would receive if it sold the entire
portfolio.

  The valuation of the portfolio instruments based upon their amortized cost and
the concomitant maintenance of the net asset value per share of $1.00 for the
Portfolio is permitted in accordance with applicable rules and regulations of
the SEC, including Rule 2a-7 under the 1940 Act, which require the Trust to
adhere to certain conditions. These rules require that the Trust maintain a
dollar-weighted average portfolio maturity of 90 days or less for the Portfolio,
purchase only instruments having remaining maturities of 397 days or less and
invest only in securities determined by the Trust's Board of Trustees to be of
high quality with minimal credit risk.

  The Board of Trustees is required to establish procedures designed to
stabilize, to the extent reasonably practicable, the Trust's price per share at
$1.00 for the Portfolio as computed for the purpose of sales and redemptions.
Such procedures include review of the Portfolio's portfolio holdings by the
Board of Trustees, at such intervals as they may deem appropriate, to determine
whether the net asset value calculated by using available market quotations or
other reputable sources for the Portfolio deviates from $1.00 per share and, if
so, whether such deviation may result in material dilution or is otherwise
unfair to existing holders of the Portfolio's shares. In the event the Board of
Trustees determines that such a deviation exists for the Portfolio, it will take
such corrective action as the Board of Trustees deems necessary and appropriate
with respect to the Portfolio, including the sales of portfolio instruments
prior to maturity to realize capital gains or losses or to shorten the average
portfolio maturity; the withholding of dividends; redemption of shares in kind;
or the establishment of a net asset value per share by using available market
quotations.

DISTRIBUTION AGREEMENT

  The Trust has entered into a Master Distribution Agreement (the "Distribution
Agreement") with FMC, a registered broker-dealer and a wholly owned subsidiary
of AIM, to act as the exclusive distributor of the shares of each class of the
Portfolio. The address of FMC is 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173. See "General Information About the Trust -- Trustees and Officers"
and "-- Investment Advisor" for information as to the affiliation of certain
trustees and officers of the Trust with FMC, AIM and AIM Management.

  The Distribution Agreement provides that FMC has the exclusive right to
distribute shares of each class of the Portfolio either directly or through
other broker-dealers. The Distribution Agreement also provides that FMC will pay
promotional expenses, including the incremental costs of printing prospectuses
and statements of additional information, annual reports and other periodic
reports for distribution to persons who are not shareholders of the Trust and
the costs of preparing and distributing any other supplemental sales literature.
FMC has not undertaken to sell any specified number of shares of the Portfolio.

  The Distribution Agreement will continue in effect from year to year only if
such continuation is specifically approved at least annually by the Trust's
Board of Trustees and the affirmative vote of the trustees who are not parties
to the Distribution Agreement or "interested persons" of any such party by votes
cast in person at a meeting called for such purpose. The Trust or FMC may
terminate the Distribution Agreement on 60 days' written notice without penalty.
The Distribution Agreement will terminate automatically in the event of its
"assignment," as defined in the 1940 Act.

  FMC may, from time to time, at its expense, pay a bonus or other consideration
or incentive to dealers or institutions who sell a minimum dollar amount of the
shares of a particular class during a specific period of time. In some
instances, these incentives may be offered only to certain dealers or
institutions who have sold or may sell significant amounts of shares. The total
amount of such additional bonus or payments or other consideration shall not
exceed 0.05% of the net asset value of the shares of the class sold. Any such
bonus or incentive programs will not change the price paid by investors for the
purchase of shares of the class or the amount received as proceeds from such
sales. Dealers or institutions may not use sales of the shares to qualify for
any incentives to the extent that such incentives may be prohibited by the laws
of any jurisdiction.

DISTRIBUTION PLAN

  The Trust has adopted a Master Distribution Plan (the "Plan") pursuant to Rule
12b-1 under the 1940 Act with respect to the Cash Management Class, Personal
Investment Class, Private Investment Class, Reserve Class and Resource Class.
The Plan provides that the Trust may compensate FMC in connection with the
distribution of shares of the Portfolio. Such compensation may be expended when
and if authorized by the Board of Trustees and may be used to finance such
distribution-related services

                                      B-20
<PAGE>   40
as expenses of organizing and conducting sales seminars, printing of
prospectuses and statements of additional information (and supplements thereto)
and reports for other than existing shareholders, preparation and distribution
of advertising material and sales literature and cost of administering the
Plan.

  Pursuant to the Plan, the Trust may enter into Shareholder Service Agreements
("Service Agreements") with selected broker-dealers, banks, other financial
institutions or their affiliates. Such firms may receive from the Portfolio
compensation for servicing investors as beneficial owners of the shares of the
Cash Management Class, Personal Investment Class, Private Investment Class,
Reserve Class and Resource Class of the Portfolio. These services may include
among other things: (i) answering customer inquiries regarding the shares of
these classes and the Portfolio; (ii) assisting customers in changing dividend
options, account designations and addresses; (iii) performing sub-accounting;
(iv) establishing and maintaining shareholder accounts and records; (v)
processing purchase and redemption transactions; (vi) automatic investment in
the shares of these classes of customer cash account balances; (vii) providing
periodic statements showing a customer's account balance and integrating such
statements with those of other transactions and balances in the customer's other
accounts serviced by such firm; (viii) arranging for bank wires; and (ix) such
other services as the Trust may request on behalf of the shares of these
classes, to the extent such firms are permitted to engage in such services by
applicable statute, rule or regulation. The Plan may only be used for the
purposes specified above and as stated in the Plan. Expenses may not be carried
over from year to year.

  The Plan does not obligate the Trust to reimburse FMC for the actual expenses
FMC may incur in fulfilling its obligations under the Plan. Thus, even if FMC's
actual expenses exceed the fee payable to FMC thereunder at any given time, the
Trust will not be obligated to pay more than that fee. If FMC's expenses are
less than the fee it receives, FMC will retain the full amount of the fee.

  FMC may from time to time waive or reduce any portion of its 12b-1 fee for
Cash Management Class, Personal Investment Class, Private Investment Class,
Reserve Class and Resource Class shares. Voluntary fee waivers or reductions may
be rescinded at any time without further notice to investors. During periods of
voluntary fee waivers or reductions, FMC will retain its ability to be
reimbursed for such fee prior to the end of each fiscal year. Contractual fee
waivers or reductions set forth in the Fee Table in a Prospectus may not be
terminated or amended to the Portfolio's detriment during the period stated in
the agreement between FMC and the Trust.

  The Plan requires the officers of the Trust to provide the Board of Trustees
at least quarterly with a written report of the amounts expended pursuant to the
Plan and the purposes for which such expenditures were made. The Board of
Trustees shall review these reports in connection with their decisions with
respect to the Plan.

  For the fiscal year ended August 31, 1999, FMC received compensation pursuant
to the Plan in the amount of $783,278, or an amount equal to 0.08% of the
average daily net assets of the Cash Management Class, $1,878,076, or an amount
equal to 0.50% of the average daily net assets of the Personal Investment Class,
$1,063,328, or an amount equal to 0.30% of the average daily net assets of the
Private Investment Class, $226,595, or an amount equal to 0.80% of the average
daily net assets of the Reserve Class, $590,788 or an amount equal to 0.16% of
the average daily net assets of the Resource Class. With respect to the Cash
Management Class, $783,278 of such amount (or an amount equal to 0.08% of the
average daily net assets of the class) was paid to dealers and financial
institutions and $0(or an amount equal to 0.0% of the average daily net assets
of the class) was retained by FMC. With respect to the Personal Investment
Class, $1,542,523 of such amount (or an amount equal to 0.40% of the average
daily net assets of the class) was paid to dealers and financial institutions
and $335,553 (or an amount equal to 0.10% of the average daily net assets of the
class) was retained by FMC. With respect to the Private Investment Class,
$955,018 of such amount (or an amount equal to 0.28% of the average daily net
assets of the class) was paid to dealers and financial institutions and $108,310
(or an amount equal to 0.03% of the average daily net assets of the class) was
retained by FMC. With respect to the Reserve Class, $212,433 of such amount (or
an amount equal to 0.08% of the average daily net assets of the class) was paid
to dealers and financial institutions and $14,162 (or an amount equal to 0.05%
of the average daily net assets of the class) was retained by FMC. With respect
to the Resource Class, $590,788 of such amount (or an amount equal to 0.16% of
the average daily net assets of the class) was paid to dealers and financial
institutions and $0 (or an amount equal to 0.0% of the average daily net assets
of the class) was retained by FMC.

  As required by Rule 12b-1 under the 1940 Act, the Plan has been approved by
the Board of Trustees, including a majority of the trustees who are not
"interested persons" (as defined in the 1940 Act) of the Trust and who have no
direct or indirect financial interest in the operation of the Plan or in any
agreements related to the Plan ("Qualified Trustees"). In approving the Plan in
accordance with the requirements of Rule 12b-1, the trustees considered various
factors and determined that there is a reasonable likelihood that the Plan would
benefit the Trust and the holders of shares of the applicable classes of the
Portfolio. Anticipated benefits that may result from the Plan are: (i) FMC,
brokerage firms and financial institutions will provide a shareholder with
repaid access to his account for the purpose of effecting executions of purchase
and redemption orders; (ii) FMC and shareholder service agents will provide
prompt, efficient and reliable responses to shareholder inquiries concerning
account status; (iii) a well-developed, dependable network of shareholder
service agents may help to curb sharp fluctuations in

                                      B-21
<PAGE>   41

rates of redemptions and sales, thereby reducing the chance that an
unanticipated increase in net redemptions could adversely affect the performance
of the Portfolio; and (iv) a successful distribution effort will assist FMC in
maintaining and increasing the organizational strength needed to service the
Portfolio.

  The Plan complies with the Conduct Rules of the National Association of
Securities Dealers, Inc. and provides for payment of a service fee to dealers
and other financial institutions that provide continuing personal shareholder
services to their customers who purchase and own shares of each applicable class
of the Portfolio, in amounts of up to 0.25% of the average net assets of such
class of the Portfolio attributable to the customers of such dealers or
financial institutions. Payments to dealers and other financial institutions in
excess of such amount and payment to FMC would be characterized as an
asset-based sales charge pursuant to the amended Plan. The Plan also imposes a
cap on the total amount of sales charges, including asset-based sales charges,
that may be paid by the Portfolio with respect to each applicable class.

  The Plan, unless sooner terminated in accordance with its terms, shall
continue in effect as to each applicable class from year to year as long as such
continuance is specifically approved at least annually by the Board of Trustees,
including a majority of the Qualified Trustees.

  FMC is a wholly owned subsidiary of AIM, an indirect wholly owned subsidiary
of AMVESCAP PLC. Charles T. Bauer, a Trustee and Chairman of the Trust, and
Robert H. Graham, a Trustee and President of the Trust, own shares of AMVESCAP
PLC.

  The Plan may be terminated as to a particular class of the Portfolio by vote
of a majority of the Qualified Trustees, or by vote of a majority of the holders
of the outstanding voting securities of such class. Any change in the Plan that
would increase materially the distribution expenses paid by an applicable class
requires shareholder approval; otherwise, the Plan may be amended by the
trustees, including a majority of the Qualified Trustees, by vote cast in person
at a meeting called for the purpose of voting upon such amendment. As long as
the Plan is in effect, the selection or nomination of the Qualified Trustees is
committed to the discretion of the Qualified Trustees.

BANKING REGULATIONS

  The Glass-Steagall Act and other applicable laws, among other things,
generally prohibit federally chartered or supervised banks from engaging in the
business of underwriting, selling or distributing securities, but permit banks
to make shares of mutual funds available to their customers and to perform
administrative and shareholder servicing functions. However, judicial or
administrative decisions or interpretations of such laws, as well as changes in
either federal or state statutes or regulations relating to the permissible
activities of banks or their subsidiaries or affiliates, could prevent a bank
from continuing to perform all or a part of its servicing activities. If a bank
were prohibited from so acting, shareholder clients of such bank would be
permitted to remain shareholders of the Trust and alternate means for continuing
the servicing of such shareholders would be sought. In such event, changes in
the operation of the Trust might occur and shareholders serviced by such bank
might no longer be able to avail themselves of any automatic investment or other
services then being provided by such bank. It is not expected that shareholders
would suffer any adverse financial consequences as a result of any of these
occurrences. In addition, state securities laws on this issue may differ from
the interpretations of federal law expressed herein and certain banks and
financial institutions may be required to register as dealers pursuant to state
law.

PERFORMANCE INFORMATION

  As stated under the caption "Performance Information--Performance Table" in
each Prospectus, yield information for the shares of each class of the Portfolio
may be obtained by calling the telephone number set forth in the Prospectus for
that class. Performance will vary from time to time and past results are not
necessarily indicative of future results. Investors should understand that
performance is a function of the type and quality of the Portfolio's investments
as well as its operating expenses and market conditions. Performance information
for the shares of the Portfolio may not provide a basis for comparison with
investments which pay fixed rates of interest for a stated period of time, with
other investments or with investment companies which use a different method of
calculating performance. A shareholder's investment in the Portfolio is not
insured or guaranteed. These factors should be carefully considered by the
investor before making an investment in the Portfolio.

  Calculations of yield will take into account the total income received by the
Portfolio. To the extent that different classes of shares bear different
expenses, the yields of such classes will vary. To the extent that institutions
charge fees in connection with services provided in conjunction with the Trust,
the yield will be lower for those beneficial owners paying such fees.

  The current yields quoted will be the net average annualized yield for an
identified period, such as seven consecutive calendar days or a month. Yields
will be computed by assuming that an account was established with a single share
(the "Single Share Account") on the first day of the period. To arrive at the
quoted yield, the net change in the value of that Single Share Account for the
period (which would include dividends accrued with respect to the share, and
dividends declared on shares purchased with dividends accrued and paid, if any,
but would not include any realized gains and losses or unrealized appreciation
or depre-

                                      B-22
<PAGE>   42

ciation and income other than investment income) will be multiplied by 365 and
then divided by the number of days in the period, with the resulting figure
carried to the nearest hundredth of one percent. The Trust may also furnish a
quotation of effective yields that assumes the reinvestment of dividends for a
365 day year and a return for the entire year equal to the average annualized
yields for the period, which will be computed by compounding the unannualized
current yields for the period by adding 1 to the unannualized current yields,
raising the sum to a power equal to 365 divided by the number of days in the
period, and then subtracting 1 from the results.

  From time to time, AIM or its affiliates may waive all or a portion of their
fees and/or assume certain expenses of the Portfolio. Voluntary fee waivers or
reductions or commitments to assume expenses may be rescinded at any time
without further notice to investors. During periods of voluntary fee waivers or
reductions or commitments to assume expenses may be rescinded at any time
without further notice to investors. During periods of voluntary fee waivers or
reductions or commitments to assume expenses, AIM will retain its ability to be
reimbursed for such fee prior to the end of each fiscal year. Contractual fee
waivers or reductions or reimbursement of expenses set forth in the Fee Table in
a Prospectus may not be terminated or amended to the Portfolio's detriment
during the period stated in the agreement between AIM and the Trust. Fee waivers
or reductions or commitments to reduce expenses will have the effect of the
increasing the Portfolio's yield and total return.

  For the seven-day period ended August 31, 1999, the current and effective
yields for the Private Investment Class were 4.80% and 4.91%, respectively. For
the seven-day period ended August 31, 1999, the current and effective yields for
the Institutional Class were 5.10% and 5.23%, respectively. For the seven-day
period ended August 31, 1999, the current and effective yields for the Cash
Management Class were 5.02% and 5.14%, respectively. For the seven-day period
ended August 31, 1999, the current and effective yields for the Personal
Investment Class were 4.60% and 4.70%, respectively. For the seven-day period
ended August 31, 1999, the current and effective yields for the Reserve Class
were 4.30% and 4.39%, respectively. For the seven-day period ended August 31,
1999, the current and effective yields for the Resource Class were 4.94% and
5.06%, respectively. These yields are quoted for illustration purposes only. The
yields for any other seven-day period may be substantially different from the
yields quoted above.

  The Trust may compare the performance of a class or the performance of
securities in which it may invest to:

          - IBC/Donoghue's Money Fund Averages, which are average yields of
     various types of money market funds that include the effect of compounding
     distributions;

          - other mutual funds, especially those with similar investment
     objectives. These comparisons may be based on data published by
     IBC/Donoghue's Money Fund Report or by Lipper, Inc., a widely recognized
     independent service, which monitors the performance of mutual funds;

          - yields on other money market securities or averages of other money
     market securities as reported by the Federal Reserve Bulletin, by TeleRate,
     a financial information network, or by Bloomberg, a financial information
     firm; and

          - other fixed-income investments such as Certificates of Deposit
     ("CDs").

  The principal value and interest rate of CDs and money market securities are
fixed at the time of purchase whereas a class's yield will fluctuate. Unlike
some CDs and certain other money market securities, money market mutual funds
are not insured by the FDIC. Investors should give consideration to the quality
and maturity of the portfolio securities of the respective investment companies
when comparing investment alternatives.

  The Trust may reference the growth and variety of money market mutual funds
and AIM's innovation and participation in the industry.

                      INVESTMENT PROGRAM AND RESTRICTIONS

INVESTMENT PROGRAM

  Information concerning the Portfolio's investment objective and operating
policies is set forth in each Prospectus. The principal features of the
Portfolio's investment program and the primary risks associated with that
investment program are also discussed in each Prospectus. There can be no
assurance that the Portfolio will achieve its objective. The values of the
securities in which the Portfolio invests fluctuate based upon interest rates,
the financial stability of the issuer and market factors. The following is a
more detailed description of the portfolio instruments eligible for purchase by
the Portfolio, which augments the summary of the Portfolio's investment program
which appears under the heading "Investment Objective and Strategies" in each
Prospectus.

  The Portfolio seeks to achieve its objective by investing in high grade money
market instruments. The money market instruments in which the Portfolio invests
are considered to carry very little risk and accordingly may not have as high a
yield as that

                                      B-23
<PAGE>   43

available on money market instruments of lesser quality. The Portfolio invests
exclusively in direct obligations of the U.S. Treasury, which include Treasury
bills, notes and bonds and repurchase agreements relating to such securities.
The Portfolio may enter into repurchase agreements with respect to U.S. Treasury
securities. The Portfolio may also borrow money and enter into reverse
repurchase agreements with respect to its portfolio securities in amounts up to
10% of the value of its total assets at the time of borrowing or entering into a
reverse repurchase agreement. The Portfolio will only borrow money or enter into
reverse repurchase agreements for temporary or emergency purposes to facilitate
the orderly sale of portfolio securities to accommodate abnormally heavy
redemption requests should they occur.

INVESTMENT POLICIES

  REPURCHASE AGREEMENTS. The Portfolio intends to invest in repurchase
agreements with banks and broker-dealers pertaining to the securities described
above and which at the date of purchase are "First Tier" securities as defined
in Rule 2a-7 under the 1940 Act, as such Rule may be amended from time to time.
Briefly, "First Tier" securities are securities that are rated in the highest
rating category for short-term debt obligations by two nationally recognized
statistical rating organizations ("NRSROs"), or, if only rated by one NRSRO, are
rated in the highest rating category by that NRSRO, or, if unrated, are
determined by the Portfolio's investment advisor (under the supervision of and
pursuant to guidelines established by the Board of Directors) to be of
comparable quality to a rated security that meets the foregoing quality
standards, as well as securities issued by a registered investment company that
is a money market fund and U.S. government securities. A repurchase agreement is
an instrument under which the Portfolio acquires ownership of a debt security
and the seller agrees, at the time of the sale, to repurchase the obligation at
a mutually agreed-upon time and price, thereby determining the yield during the
Portfolio's holding period. Repurchase transactions are limited to a term not to
exceed 365 days. The Portfolio may enter into repurchase agreements only with
institutions believed by the Trust's Board of Trustees to present minimal credit
risk. With regard to repurchase transactions, in the event of a bankruptcy or
other default of a seller of a repurchase agreement (such as the seller's
failure to repurchase the obligation in accordance with the terms of the
agreement), the Portfolio could experience both delays in liquidating the
underlying securities and losses, including: (a) a possible decline in the value
of the underlying security during the period while the Portfolio seeks to
enforce its rights thereto, (b) possible subnormal levels of income and lack of
access to income during this period, and (c) expenses of enforcing its rights.
Repurchase agreements are considered to be loans under the 1940 Act.

  BORROWING MONEY/REVERSE REPURCHASE AGREEMENTS. The Portfolio may borrow money
and enter into reverse repurchase agreements with respect to its portfolio
securities in amounts up to 10% of the value of its total assets at the time of
borrowing or entering into a reverse repurchase agreement. Reverse repurchase
agreements involve the sale by the Portfolio of a portfolio security at an
agreed-upon price, date and interest payment. The Portfolio will borrow money or
enter into reverse repurchase agreements solely for temporary or defensive
purposes, such as to facilitate the orderly sale of portfolio securities or to
accommodate abnormally heavy redemption requests should they occur. Reverse
repurchase transactions are limited to a term not to exceed 92 days. The
Portfolio will use reverse repurchase agreements when the interest income to be
earned from the securities that would otherwise have to be liquidated to meet
redemption requests is greater than the interest expense of the reverse
repurchase transaction. The Portfolio will give shareholders notice of its
intent to enter into a reverse repurchase agreement in sufficient time to permit
shareholder redemptions before the Portfolio enters into any reverse repurchase
agreements. Reverse repurchase agreements involve the risk that the market value
of securities retained by the Portfolio in lieu of liquidation may decline below
the repurchase price of the securities sold by the Portfolio which it is
obligated to repurchase. The risk, if encountered, could cause a reduction in
the net asset value of the Portfolio's shares. Reverse repurchase agreements are
considered to be borrowings by the Portfolio under the 1940 Act.

  LENDING OF PORTFOLIO SECURITIES. The Portfolio may also lend its portfolio
securities in amounts up to 33 1/3% of its total assets to financial
institutions in accordance with the investment restrictions of the Portfolio.
Such loans would involve risks of delay in receiving additional collateral in
the event the value of the collateral decreased below the value of the
securities loaned or of delay in recovering the securities loaned or even loss
of rights in the collateral should the borrower of the securities fail
financially. However, loans will be made only to borrowers deemed by AIM to be
of good standing and only when, in AIM's judgement, the income to be earned from
the loans justifies the attendant risks.

  PURCHASING DELAYED DELIVERY SECURITIES. In managing the Portfolio's
investments, AIM may indicate to dealers or issuers its interest in acquiring
certain securities for the Portfolio for settlement beyond a customary
settlement date. In some cases, the Portfolio may agree to purchase such
securities at stated prices and yields. In such cases, such securities are
considered "delayed deliver" securities when traded in the secondary market.
Since this is done to facilitate the acquisition of portfolio securities and is
not for the purpose of investment leverage, the amount of delayed delivery
securities involved may not exceed the estimated amount of funds available for
investment on the settlement date. Until the settlement date, liquid assets of
the Portfolio with a dollar value sufficient at all times to make payment for
the delayed delivery securities will be segregated. The total amount of
segregated liquid assets may not exceed 25% of the Portfolio's total assets. The
delayed delivery securities,

                                      B-24
<PAGE>   44

which will not begin to accrue interest until the settlement date, will be
recorded as an asset of the Portfolio and will be subject to the risks of market
value fluctuations. The repurchase price of the delayed delivery securities will
be recorded as a liability of the Portfolio until settlement. Absent
extraordinary circumstances, the Portfolio's right to acquire delayed delivery
securities will not be divested prior to the settlement date.

  ILLIQUID SECURITIES. The Portfolio will invest no more than 10% of its net
assets in illiquid securities.

  PORTFOLIO TRANSACTIONS. The Portfolio does not seek profits through short-term
trading and will generally hold portfolio securities to maturity, but AIM may
seek to enhance the yield of the Portfolio by taking advantage of yield
disparities or other factors that occur in the money markets. For example,
market conditions frequently result in similar securities trading at different
prices. AIM may dispose of any portfolio security prior to its maturity if such
disposition and reinvestment of proceeds are expected to enhance yield
consistent with AIM's judgement as to desirable portfolio maturity structure or
if such disposition is believed to be advisable due to other circumstances or
conditions. Securities held by the Portfolio will be disposed of prior to
maturity if an earlier disposition is deemed desirable by AIM to meet redemption
requests. In addition, AIM will continually monitor the creditworthiness of
issuers whose securities are held by the Portfolio, and securities held by the
Portfolio may be disposed of prior to maturity as a result of a revised credit
evaluation of the issuer or other circumstances or considerations. The
Portfolio's policy of investing in securities with maturities of 397 days or
less will result in high portfolio turnover. Since brokerage commissions are not
normally paid on investments of the type made by the Portfolio, the high
turnover rate should not adversely affect the Portfolio's net income.

ELIGIBLE SECURITIES

  The Trust will invest in "Eligible Securities" as defined in Rule 2a-7 under
the 1940 Act, which the Trust's Board of Trustees has determined to present
minimal credit risk.

INVESTMENT RESTRICTIONS

  As a matter of fundamental policy which may not be changed without a majority
vote of shareholders of the Portfolio (as that term is defined under "General
Information about the Trust -- The Trust and its Shares"), the Portfolio may
not:

          (1) concentrate more than 25% of the value of its total assets in the
     securities of one or more issuers conducting their principal business
     activities in the same industry, provided that there is no limitation with
     respect to investments in obligations issued or guaranteed by the U.S.
     Government, its agencies or instrumentalities and bank instruments, such as
     CDs, bankers' acceptances, time deposits and bank repurchase agreements;

          (2) purchase securities of any one issuer (other than obligations of
     the U.S. Government, its agencies or instrumentalities) if, immediately
     after such purchase, more than 5% of the value of the Portfolio's total
     assets would be invested in such issuer, except as permitted by Rule 2a-7
     under the 1940 Act, as amended from time to time, and except that the
     Portfolio may purchase securities of other investment companies to the
     extent permitted by applicable law or exemptive order; or

          (3) borrow money or issue senior securities except (a) for temporary
     or emergency purposes (e.g., in order to facilitate the orderly sale of
     portfolio securities to accommodate abnormally heavy redemption requests),
     the Portfolio may borrow money from banks or obtain funds by entering into
     reverse repurchase agreements, and (b) to the extent that entering into
     commitments to purchase securities in accordance with the Portfolio's
     investment program may be considered the issuance of senior securities,
     provided that the Portfolio will not purchase portfolio securities while
     borrowings in excess of 5% of its total assets are outstanding;

          (4) mortgage, pledge or hypothecate any assets except to secure
     permitted borrowings and except for reverse repurchase agreements and then
     only in an amount up to 33 1/3% of the value of its total assets at the
     time of borrowing or entering into a reverse repurchase agreement;

          (5) make loans of money or securities other than (a) through the
     purchase of debt securities in accordance with the Portfolio's investment
     program, (b) by entering into repurchase agreements and (c) by lending
     portfolio securities to the extent permitted by law or regulation;

          (6) underwrite securities issued by any other person, except to the
     extent that the purchase of securities and the later disposition of such
     securities in accordance with the Portfolio's investment program may be
     deemed an underwriting;

          (7) invest in real estate, except that the Portfolio may purchase and
     sell securities secured by real estate or interests therein or issued by
     issuers which invest in real estate or interests therein;

                                      B-25
<PAGE>   45

          (8) purchase or sell commodities or commodity futures contracts,
     purchase securities on margin, make short sales or invest in puts or calls;
     or

          (9) invest in any obligation not payable as to principal and interest
     in United States currency.

OTHER INVESTMENT POLICIES

  The Portfolio does not intend to invest in companies for the purpose of
exercising control or management, except that the Portfolio may purchase
securities of other investment companies to the extent permitted by the 1940
Act, and rules and regulations thereunder, and, if applicable, exemptive orders
granted by the SEC. The Portfolio has obtained an exemptive order from the SEC
allowing it to invest in money market funds that have AIM or an affiliate of AIM
as an investment advisor (the "Affiliated Money Market Fund"), provided that
investments in Affiliated Money Market Funds do not exceed 25% of the total
assets of the Portfolio. If other funds advised by AIM invest in the Portfolio,
however, the Portfolio will be subject to the provisions of Section 12(d)(1) of
the 1940 Act, which limits the ability of an investment company to invest in
another investment company. With respect to the Portfolio's purchase of shares
of the Affiliated Money Market Funds, the Portfolio will indirectly pay the
advisory fees and other operating expenses of the Affiliated Money Market Funds.
The foregoing policy is non-fundamental.

                      PORTFOLIO TRANSACTIONS AND BROKERAGE

GENERAL BROKERAGE POLICY

  AIM makes decisions to buy and sell securities for the Portfolio, selects
broker-dealers, effects the Portfolio's investment portfolio transactions,
allocates brokerage fees in such transactions, and where applicable, negotiates
commissions and spreads on transactions. Since purchases and sales of portfolio
securities by the Portfolio are usually principal transactions, the Portfolio
incurs little or no brokerage commissions. AIM's primary consideration in
effecting a security transaction is to obtain the most favorable execution of
the order, which includes the best price on the security and a low commission
rate (as applicable). While AIM seeks reasonable competitive commission rates,
the Portfolio may not pay the lowest commission or spread available. See
"Section 28(e) Standards" below.

  In the event the Portfolio purchases securities traded in over-the-counter
markets, the Portfolio deals directly with dealers who make markets in the
securities involved, except when better prices are available elsewhere.
Portfolio transactions placed through dealers who are primary market makers are
effected at net prices without commissions, but which include compensation in
the form of a mark up or mark down.

  AIM may determine target levels of commission business with various brokers on
behalf of its clients (including the Portfolio) over a certain time period. The
target levels will be based upon the following factors, among others: (1) the
execution services provided by the broker; (2) the research services provided by
the broker; and (3) the broker's interest in mutual funds in general and in the
Portfolio and other mutual funds advised by AIM or A I M Capital Management,
Inc. (collectively, the "AIM Funds") in particular, including sales of the
Portfolio and of the other AIM Funds. In connection with (3) above, the
Portfolio's trades may be executed directly by dealers which sell shares of the
AIM Funds or by other broker-dealers with which such dealers have clearing
arrangements. AIM will not use a specific formula in connection with any of
these considerations to determine the target levels.

  AIM will seek, whenever possible, to recapture for the benefit of a Portfolio
any commissions, fees, brokerage or similar payments paid by the Portfolio on
portfolio transactions. Normally, the only fees which AIM can recapture are the
soliciting dealer fees on the tender of the Portfolio's securities in a tender
or exchange offer.

  The Portfolio may engage in certain principal and agency transactions with
banks and their affiliates that own 5% or more of the outstanding voting
securities of the Portfolio provided the conditions of an exemptive order
received by the Portfolio from the SEC are met. In addition, the Portfolio may
purchase or sell a security from or to another AIM Fund provided the Portfolio
follows procedures adopted by the Board of Directors/Trustees of the various AIM
Funds, including the Trust. These inter-fund transactions do not generate
brokerage commissions but may result in custodial fees or taxes or other related
expenses.

  The Portfolio does not seek to profit from short-term trading, and will
generally (but not always) hold portfolio securities to maturity, but AIM may
seek to enhance the yield of the Portfolio by taking advantage of yield
disparities or other factors that occur in the money markets. For example,
market conditions frequently result in similar securities trading at different
prices. AIM may dispose of any portfolio security prior to its maturity if such
disposition and reinvestment of proceeds are expected to enhance yield
consistent with AIM's judgment as to desirable portfolio maturity structure or
if such disposition is believed to be advisable due to other circumstances or
conditions. The amortized cost method of valuing portfolio securities requires
that the Portfolio maintain an average weighted portfolio maturity of ninety
days or less. Thus, there is likely to be relatively high port-

                                      B-26
<PAGE>   46

folio turnover, but since brokerage commissions are not normally paid on money
market instruments, the high rate of portfolio turnover is not expected to have
a material effect on the net income or expenses of the Portfolio. The
Portfolio's policy of investing in securities with maturities of 397 days or
less will result in high portfolio turnover. Since brokerage commissions are not
normally paid on investments of the type made by the Portfolio, the high
turnover rate should not adversely affect the Portfolio's net income.

  Under the 1940 Act, certain persons affiliated with the Trust are prohibited
from dealing with the Portfolios as principal in any purchase or sale of
securities unless an exemptive order allowing such transactions is obtained from
the SEC. Furthermore, the 1940 Act prohibits the Trust from purchasing a
security being publicly underwritten by a syndicate of which certain persons
affiliated with the Trust are members except in accordance with certain
conditions. These conditions may restrict the ability of the Portfolio to
purchase money market obligations being publicly underwritten by such a
syndicate, and the Portfolio may be required to wait until the syndicate has
been terminated before buying such securities. At such time, the market price of
the securities may be higher or lower than the original offering price. A person
affiliated with the Trust may, from time to time, serve as placement agent or
financial advisor to an issuer of money market obligations and be paid a fee by
such issuer. The Portfolio may purchase such money market obligations directly
from the issuer, provided that the purchase is made in accordance with
procedures adopted by the Trust's Board of Trustees and any such purchases are
reviewed at least quarterly by the Trust's Board of Trustees and a determination
is made that all such purchases were effected in compliance with such
procedures, including a determination that the placement fee or other
remuneration paid by the issuer to the person affiliated with the Trust was fair
and reasonable in relation to the fees charged by others performing similar
services.

ALLOCATION OF PORTFOLIO TRANSACTIONS

  AIM and its affiliates manage several other investment accounts. Some of these
accounts may have investment objectives similar to the Portfolio. Occasionally,
identical securities will be appropriate for investment by the Portfolio and by
another fund or one or more of these investment accounts. However, the position
of each account in the same securities and the length of time that each account
may hold its investment in the same securities may vary. The timing and amount
of purchase by each account will also be determined by its cash position. If the
purchase or sale of securities is consistent with the investment policies of the
Portfolio and one or more of these accounts, and is considered at or about the
same time, AIM will fairly allocate transactions in such securities among the
Portfolio and these accounts. AIM may combine such transactions, in accordance
with applicable laws and regulations, to obtain the most favorable execution.
Simultaneous transactions could, however, adversely affect the Portfolio's
ability to obtain or dispose of the full amount of a security which it seeks to
purchase or sell.

  Sometimes the procedure for allocating portfolio transactions among the
various investment accounts advised by AIM could have an adverse effect on the
price or amount of securities available to the Portfolio. In making such
allocations, AIM considers the investment objectives and policies of its
advisory clients, the relative size of portfolio holdings of the same or
comparable securities, the availability of cash for investment, the size of
investment commitments generally held, and the judgments of the persons
responsible for recommending the investment.

SECTION 28(e) STANDARDS

  Section 28(e) of the Securities Exchange Act of 1934 provides that AIM, under
certain circumstances, lawfully may cause an account to pay a higher commission
than the lowest available. Under Section 28(e), AIM must make a good faith
determination that the commissions paid are "reasonable in relation to the value
of the brokerage and research services provided . . . viewed in terms of either
that particular transaction or [AIM's] overall responsibilities with respect to
the accounts as to which it exercises investment discretion." The services
provided by the broker also must lawfully and appropriately assist AIM in the
performance of its investment decision-making responsibilities. Accordingly, in
recognition of research services provided to it, a Fund may pay a broker higher
commissions than those available from another broker.

  Research services received from broker-dealers supplement AIM's own research
(and the research of its affiliates), and may include the following types of
information: statistical and background information on the U.S. and foreign
economies, industry groups and individual companies; forecasts and
interpretations with respect to the U.S. and foreign economies, securities,
markets, specific industry groups and individual companies; information on
federal, state, local and foreign political developments; portfolio management
strategies; performance information on securities, indexes and investment
accounts; information concerning prices of securities; and information supplied
by specialized services to AIM and to the Trust's trustees with respect to the
performance, investment activities, and fees and expenses of other mutual funds.
Broker-dealers may communicate such information electronically, orally, in
written form or on computer software. Research services may also include the
providing of custody services, as well as the providing of equipment used to
communicate research information, the providing of specialized consultations
with AIM personnel with respect to computerized systems and data furnished to
AIM as a component of other research services, the arranging of meetings with
management of companies, and the providing of access to consultants who supply
research information.

                                      B-27
<PAGE>   47

  The outside research assistance is useful to AIM since the broker-dealers used
by AIM tend to follow a broader universe of securities and other matters than
AIM's staff can follow. In addition, the research provides AIM with a diverse
perspective on financial markets. Research services provided to AIM by
broker-dealers are available for the benefit of all accounts managed or advised
by AIM or by its affiliates. Some broker-dealers may indicate that the provision
of research services is dependent upon the generation of certain specified
levels of commissions and underwriting concessions by AIM's clients, including
the Portfolio. However, the Portfolio is not under any obligation to deal with
any broker-dealer in the execution of transactions in portfolio securities.

  In some cases, the research services are available only from the broker-dealer
providing them. In other cases, the research services may be obtainable from
alternative sources in return for cash payments. AIM believes that the research
services are beneficial in supplementing AIM's research and analysis and that
they improve the quality of AIM's investment advice. The advisory fee paid by
the Portfolio is not reduced because AIM receives such services. However, to the
extent that AIM would have purchased research services had they not been
provided by broker-dealers, the expenses to AIM could be considered to have been
reduced accordingly.

                    DIVIDENDS, DISTRIBUTIONS AND TAX MATTERS

DIVIDENDS AND DISTRIBUTIONS

  Dividends with respect to each class of the Portfolio are declared to
shareholders of record as of 5:00 p.m. Eastern time on the date of
declaration. Accordingly, dividends accrue on the first day that a purchase
order for shares of a particular class is effective, provided that the purchase
order has been accepted prior to 5:00 p.m. Eastern time and payment in the form
of federal funds wired has been received by AFS. Dividends do not accrue on the
day that a redemption order is effective, unless the redemption is effective
after 5:00 p.m. Eastern time on that day and redemption proceeds have not been
wired to the shareholder on the same day. Thus, if a purchase order is accepted
prior to 5:00 p.m. Eastern time, the shareholder will receive its pro rata share
of dividends beginning with those declared on that day.

  Dividends and distributions are paid in cash unless the shareholder has
elected to have such dividends and distributions reinvested in the form of
additional full and fractional shares at the net asset value hereof. Such
election, or any revocation thereof, must be made in writing and sent by the
shareholder to the AFS at P.O. Box 4497, Houston, Texas 77210-4497. Such
election or revocation will be effective with dividends paid after it is
received by the transfer agent.

  All dividends declared during a month will normally be paid by wire transfer.
Payment will normally be made on the first business day of the following month.
If a shareholder redeems all the shares in his account at any time during the
month, all dividends declared through the date of redemption are paid to the
shareholder along with the proceeds of the redemption. Information concerning
the amount of the dividends declared on any particular day will normally be
available by 6:00 p.m. Eastern time on that day.

  The dividend accrued and paid for each class of shares of the Portfolio will
consist of: (a) interest accrued and original issue discount earned less
amortization of premiums, if any, for the portfolio to which such class relates,
allocated based upon such class' pro rata share of the total shares outstanding
which relate to such portfolio, less (b) Trust expenses accrued for the
applicable dividend period attributable to such portfolio, such as custodian
fees and accounting expenses, allocated based upon each such class' pro rata of
the net assets of such portfolio, less (c) expenses directly attributable to
each class which are accrued for the applicable dividend period, such as
distribution expenses, if any.

  Should the Trust incur or anticipate any unusual expense, loss or
depreciation, which would adversely affect the net asset value per share of the
Portfolio or the net income per share of a class of the Portfolio for a
particular period, the Board of Trustees would at that time consider whether to
adhere to the present dividend policy described above or to revise it in light
of then prevailing circumstances. For example, if the net asset value per share
of the Portfolio were reduced, or were anticipated to be reduced, below $1.00,
the Board of Trustees might suspend further dividend payments on shares of the
Portfolio until the net asset returns to $1.00. Thus, such expense or loss or
depreciation might result in a shareholder receiving no dividends for the period
during which it held shares of the Portfolio and/or in its receiving upon
redemption a price per share lower than that which it paid.

TAX MATTERS

  The following is only a summary of certain additional tax considerations
generally affecting the Portfolio and its shareholders that are not described in
the Prospectus. No attempt is made to present a detailed explanation of the tax
treatment of the Portfolio or its shareholders, and the discussion here and in
the Prospectus is not intended as a substitute for careful tax planning.

                                      B-28
<PAGE>   48

QUALIFICATION AS A REGULATED INVESTMENT COMPANY

  The Portfolio has elected to be taxed as a regulated investment company under
Subchapter M of the Internal Revenue Code of 1986, as amended (the "Code"). As a
regulated investment company, the Portfolio is not subject to federal income tax
on the portion of its net investment income (i.e., taxable interest, dividends
and other taxable ordinary income, net of expenses) and capital gain net income
(i.e., the excess of capital gains over capital losses) that it distributes to
shareholders, provided that it distributes at least 90% of its investment
company taxable income (i.e., net investment income and the excess of net
short-term capital gain over net long-term capital loss) for the taxable year
(the "Distribution Requirement"), and satisfies certain other requirements of
the Code that are described below. Distributions by the Portfolio made during
the taxable year or, under specified circumstances, within twelve months after
the close of the taxable year, will be considered distributions of income and
gains for the taxable year and can therefore satisfy the Distribution
Requirement.

  In addition to satisfying the Distribution Requirement, a regulated investment
company (1) must derive at least 90% of its gross income from dividends,
interest, certain payments with respect to securities loans, gains from the sale
or other disposition of stock or securities or foreign currencies (to the extent
such currency gains are directly related to the regulated investment company's
principal business of investing in stock or securities) and other income
(including but not limited to gains from options, futures or forward contracts)
derived with respect to its business of investing in such stock, securities or
currencies (the "Income Requirement"); and (2) must satisfy an asset
diversification test in order to qualify for tax purposes as a regulated
investment company (the "Asset Diversification Test"). Under the Asset
Diversification Test, at the close of each quarter of a fund's taxable year, at
least 50% of the value of a fund's assets must consist of cash and cash items,
U.S. Government securities, securities of other regulated investment companies,
and securities of other issuers (as to which a fund has not invested more than
5% of the value of a fund's total assets in securities of such issuer and as to
which a fund does not hold more than 10% of the outstanding voting securities of
such issuer), and no more than 25% of the value of its total assets may be
invested in the securities of any other issuer (other than U.S. Government
securities and securities of other regulated investment companies), or in two or
more issuers which a fund controls and which are engaged in the same or similar
trades or businesses.

  If, for any taxable year the Portfolio does not qualify as a regulated
investment company, all of its taxable income (including its net capital gain)
will be subject to tax at regular corporate rates without any deduction for
distributions to shareholders, and such distributions will be taxable as
ordinary dividends to the extent of the Portfolio's current and accumulated
earnings and profits. Such distributions generally will be eligible for the
dividends received deduction in the case of corporate shareholders.

EXCISE TAX ON REGULATED INVESTMENT COMPANIES

  A 4% non-deductible excise tax is imposed on a regulated investment company
that fails to distribute in each calendar year an amount equal to 98% of
ordinary taxable income for the calendar year and 98% of capital gain net income
for the one-year period ended on October 31 of such calendar year (or, at the
election of a regulated investment company having a taxable year ending November
30 or December 31, for its taxable year( a "taxable year election")). The
balance of such income must be distributed during the next calendar year. For
the foregoing purposes, a regulated investment company is treated as having
distributed any amount on which it is subject to income tax for any taxable year
ending in such calendar year.

  The Portfolio intends to make sufficient distributions or deemed distributions
of its ordinary taxable income and capital gain net income prior to the end of
each calendar year to avoid liability for the excise tax. However, investors
should note that the Portfolio may in certain circumstances be required to
liquidate portfolio investments to make sufficient distributions to avoid excise
tax liability.

PORTFOLIO DISTRIBUTIONS

  The Portfolio anticipates distributing substantially all of its investment
company taxable income for each taxable year. Such distributions will be taxable
to shareholders as ordinary income and treated as dividends for federal income
tax purposes, but they will not qualify for the 70% dividends received deduction
for corporations.

  The Portfolio may either retain or distribute to shareholders its net capital
gain, if any, for each taxable year. The Portfolio currently intends to
distribute any such amounts. If net capital gain is distributed and designated
as a capital gain dividend, it will be taxable to shareholders as long-term
capital gain, regardless of the length of time the shareholder has held his
shares or whether such gain was recognized by the Portfolio prior to the date on
which the shareholder acquired his shares.

  Distributions by the Portfolio that do not constitute ordinary income
dividends or capital gain dividends will be treated as a return of capital to
the extent of (and in reduction of) the shareholder's tax basis in his shares;
any excess will be treated as gain from the sale of this shares.

                                      B-29
<PAGE>   49

  Distributions by the Portfolio will be treated in the manner described above
regardless of whether such distributions are paid in cash or reinvested in
additional shares of the Portfolio. Shareholders receiving a distribution in the
form of additional shares will be treated as receiving a distribution in an
amount equal to the fair market value of the shares received, determined as of
the reinvestment date.

  Ordinarily, shareholders are required to take distributions by the Portfolio
into account in the year in which the distributions are made. However, dividends
declared in October, November or December of any year and payable to
shareholders of record on a specified date in such a month will be deemed to
have been received by the shareholders (and made by the Portfolio) on December
31 of such calendar year if such dividends are actually paid in January of the
following year. Shareholders will be advised annually as to the U.S. federal
income tax consequences of distributions made (or deemed made) during the year
in accordance with the guidance that has been provided by the Internal Revenue
Service.

  The Portfolio will be required in certain cases to withhold and remit to the
U.S. Treasury 31% of the dividends, and in certain cases, of the proceeds of
redemption of shares, paid to any shareholder (1) who has provided either an
incorrect tax identification number or no number at all, (2) who is subject to
backup withholding by the Internal Revenue Service for failure to report the
receipt of interest or dividend income properly, or (3) who has failed to
certify to the Trust that it is not subject to backup withholding or that it is
a corporation or other "exempt recipient."

SALE OR REDEMPTION OF SHARES

  A shareholder will recognize gain or loss on the sale or redemption of shares
of a class in an amount equal to the difference between the proceeds of the sale
or redemption and the shareholder's adjusted tax basis in the shares. All or a
portion of any loss so recognized may be disallowed if the shareholder purchases
other shares of the class within 30 days before or after the sale or redemption.
In general, any gain or loss arising from (or treated as arising from) the sale
or redemption of shares of a class will be considered capital gain or loss and
will be long-term capital gain (taxable at a maximum rate of 20% for
noncorporate shareholders) or loss if the shares were held for longer than one
year. However, any capital loss arising from the sale or redemption of shares
held for six months or less will be treated as a long-term capital loss to the
extent of the amount of capital gain dividends received on such shares. For this
purpose, the special holding period rules of Code Section 246(c)(3) and (4)
generally will apply in determining the holding period of shares.

FOREIGN SHAREHOLDERS

  Taxation of a shareholder who, as to the United States, is a nonresident alien
individual, foreign trust or estate, foreign corporation, or foreign partnership
("foreign shareholder"), depends on whether the income from the Portfolio is
"effectively connected" with a U.S. trade or business carried on by such
shareholder.

  If the income from the Portfolio is not effectively connected with a U.S.
trade or business carried on by a foreign shareholder, dividends and
distributions (other than capital gains dividends) will be subject to U.S.
withholding tax at the rate of 30% (or lower treaty rate) upon the gross amount
of the dividend or distribution. Such a foreign shareholder would generally be
exempt from U.S. federal income tax on gains realized on the sale of shares of a
class, capital gain dividends and amounts retained by the Portfolio that are
designated as undistributed capital gains.

  If the income from the Portfolio is effectively connected with a U.S. trade or
business carried on by a foreign shareholder, then ordinary income dividends,
capital gain dividends and any gains realized upon the sale of shares of the
Portfolio will be subject to U.S. federal income tax at the rates applicable to
U.S. citizens or domestic corporations.

  In the case of foreign noncorporate shareholders, the Portfolio may be
required to withhold U.S. federal income tax at a rate of 31% on distributions
that are otherwise exempt from withholding tax unless such shareholders furnish
the Portfolio with proper notification of their foreign status.

  The tax consequences to a foreign shareholder entitled to claim the benefits
of an applicable tax treaty may be different from those described herein.
Foreign shareholders are urged to consult their own tax advisers with respect to
the particular tax consequences to them of an investment in the Portfolio,
including the applicability of foreign taxes.

  Foreign persons who file a United States tax return for a U.S. tax refund and
who are not eligible to obtain a social security number must apply to the
Internal Revenue Service (IRS) for an individual taxpayer identification number,
using IRS Form W-7. For a copy of the IRS Form W-7 and accompanying
instructions, please contact your tax advisor or transfer agent.

                                      B-30
<PAGE>   50

EFFECT OF FUTURE LEGISLATION; LOCAL TAX CONSIDERATIONS

  The foregoing general discussion of U.S. federal income tax consequences is
based on the Code and the regulations issued thereunder as in effect on November
1, 1999. Future legislative or administrative changes or court decisions may
significantly change the conclusions expressed herein, and any such changes or
decisions may have a retroactive effect with respect to the transactions
contemplated herein.

  Rules of state and local taxation of ordinary income dividends and capital
gain dividends from regulated investment companies often differ from the rules
for U.S. federal income taxation described above. Shareholders are urged to
consult their tax advisers as to the consequences of these and other state and
local tax rules affecting investment in the Trust.

                                      B-31
<PAGE>   51

                              FINANCIAL STATEMENTS

                                       FS
<PAGE>   52

INDEPENDENT AUDITORS' REPORT

To the Board of Trustees and Shareholders
Short-Term Investments Trust:

We have audited the accompanying statement of assets and liabilities of
Treasury Portfolio (a series portfolio of Short-Term Investments Trust),
including the schedule of investments, as of August 31, 1999, and the related
statement of operations for the year then ended, the statement of changes in
net assets for each of the two years in the period then ended, and the
financial highlights for the period January 4, 1999 (date sales commenced for
the Reserve Class) through August 31, 1999. These financial statements and
financial highlights are the responsibility of the Fund's management. Our
responsibility is to express an opinion on these financial statements and
financial highlights based on our audit.
 We conducted our audit in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements and financial
highlights are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements. Our procedures included confirmation of securities owned as of
August 31, 1999 by correspondence with the custodian. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audit provides a reasonable basis for our opinion.
 In our opinion, the financial statements and financial highlights referred to
above present fairly, in all material respects, the financial position of
Treasury Portfolio as of August 31, 1999, the results of its operations for the
year then ended, the changes in its net assets for each of the two years in the
period then ended, and the financial highlights for the period January 4, 1999
(date sales commenced for the Reserve Class) through August 31, 1999, in
conformity with generally accepted accounting principles.

KPMG LLP

October 1, 1999
Houston, Texas

                                      FS-1

<PAGE>   53


SCHEDULE OF INVESTMENTS
August 31, 1999

                                                      PAR
                                           MATURITY  (000)       VALUE
U.S. TREASURY SECURITIES - 18.03%

U.S. TREASURY BILLS(a) - 2.85%

4.49%                                      11/04/99 $ 50,000 $   49,600,889
- ---------------------------------------------------------------------------
4.631%                                     11/18/99   25,000     24,749,178
- ---------------------------------------------------------------------------
4.48%                                      12/09/99   50,000     49,383,312
- ---------------------------------------------------------------------------
4.615%                                     01/06/00   25,000     24,592,983
- ---------------------------------------------------------------------------
                                                                148,326,362
- ---------------------------------------------------------------------------

U.S. TREASURY NOTES - 15.18%

5.75%                                      09/30/99   75,000     75,061,771
- ---------------------------------------------------------------------------
7.125%                                     09/30/99   50,000     50,095,927
- ---------------------------------------------------------------------------
5.625%                                     10/31/99   80,000     80,113,813
- ---------------------------------------------------------------------------
7.50%                                      10/31/99   50,000     50,229,754
- ---------------------------------------------------------------------------
7.75%                                      11/30/99   55,612     56,002,337
- ---------------------------------------------------------------------------
5.625%                                     12/31/99   75,000     75,156,752
- ---------------------------------------------------------------------------
7.75%                                      12/31/99  100,000    100,822,053
- ---------------------------------------------------------------------------
6.375%                                     01/15/00   50,000     50,235,197
- ---------------------------------------------------------------------------
5.375%                                     01/31/00   25,000     25,056,803
- ---------------------------------------------------------------------------
7.75%                                      01/31/00   25,000     25,301,941
- ---------------------------------------------------------------------------
5.875%                                     02/15/00  100,000    100,380,204
- ---------------------------------------------------------------------------
8.50%                                      02/15/00   75,000     76,242,207
- ---------------------------------------------------------------------------
6.75%                                      04/30/00   25,000     25,220,193
- ---------------------------------------------------------------------------
                                                                789,918,952
- ---------------------------------------------------------------------------
   Total U.S. Treasury Securities (Cost
    $938,245,314)                                               938,245,314
- ---------------------------------------------------------------------------
   Total Investments (excluding Repurchase
    Agreements)                                                 938,245,314
- ---------------------------------------------------------------------------

REPURCHASE AGREEMENTS(b) - 82.11%

BancAmerica Robertson Stephens(c)
 5.43%                                     09/01/99  225,000    225,000,000
- ---------------------------------------------------------------------------
Barclays Capital, Inc.(d)
 5.43%                                     09/01/99  225,000    225,000,000
- ---------------------------------------------------------------------------
Bear, Stearns & Co. Inc.(e)
 5.43%                                           --  150,000    150,000,000
- ---------------------------------------------------------------------------
Bear, Stearns & Co. Inc.(f)
 5.17%                                     01/24/00  200,000    200,000,000
- ---------------------------------------------------------------------------
Chase Securities Inc.(g)
 5.43%                                     09/01/99  225,000    225,000,000
- ---------------------------------------------------------------------------
CIBC Oppenheimer Corp.(h)
 5.43%                                     09/01/99  225,000    225,000,000
- ---------------------------------------------------------------------------
Credit Suisse First Boston Corp.(i)
 5.23%                                     02/14/00  200,000    200,000,000
- ---------------------------------------------------------------------------
Deutsche Bank Securities, Inc.(j)
 5.43%                                           --  800,000    800,000,000
- ---------------------------------------------------------------------------

                                     FS-2
<PAGE>   54

                                                        PAR
                                             MATURITY  (000)       VALUE
REPURCHASE AGREEMENTS - (continued)

Merrill Lynch Government Securities, Inc(k)
 5.43%                                       09/01/99 $225,000 $  225,000,000
- --------------------------------------------------------------------------------
Salomon Smith Barney Inc.(l)
 5.43%                                       09/01/99  750,000    750,000,000
- --------------------------------------------------------------------------------
Societe Generale Cowen Securities Corp.(m)
 5.43%                                       09/01/99  500,000    500,000,000
- --------------------------------------------------------------------------------
State Street Bank & Trust Co.(n)
 5.43%                                       09/01/99  225,000    225,000,000
- --------------------------------------------------------------------------------
Warburg Dillon Read LLC(o)
 5.34%                                       02/01/00  100,000    100,000,000
- --------------------------------------------------------------------------------
Warburg Dillon Read LLC(p)
 5.42%                                       09/01/99  222,630    222,630,039
- --------------------------------------------------------------------------------
   Total Repurchase Agreements (Cost
    $4,272,630,039)                                             4,272,630,039
- --------------------------------------------------------------------------------
TOTAL INVESTMENTS - 100.14%                                     5,210,875,353(q)
- --------------------------------------------------------------------------------
LIABILITIES LESS OTHER ASSETS - (0.14)%                            (7,128,247)
- --------------------------------------------------------------------------------
NET ASSETS - 100.00%                                           $5,203,747,106
================================================================================
NOTES TO SCHEDULE OF INVESTMENTS:
(a) U.S. Treasury bills are traded on a discount basis. In such cases the
    interest rate shown represents the rate of discount paid or received at the
    time of purchase by the Portfolio.
(b) Collateral on repurchase agreements, including the Portfolio's pro-rata
    interest in joint repurchase agreements, is taken into possession by the
    Portfolio upon entering into the repurchase agreement. The collateral is
    marked to market daily to ensure its market value is at least 102% of the
    sales price of the repurchase agreement. The investments in some repurchase
    agreements are through participation in joint accounts with other mutual
    funds, private accounts and certain non-registered investment companies
    managed by the investment advisor or its affiliates.
(c) Repurchase agreement entered into 08/31/99 with a maturing value of
    $225,033,938. Collateralized by $209,140,000 U.S. Treasury obligations,
    4.00% to 13.75% due 02/15/00 to 02/15/07 with an aggregate market value at
    08/31/99 of $229,996,602.
(d) Repurchase agreement entered into 08/31/99 with a maturing value of
    $225,033,938. Collateralized by $230,079,000 U.S. Treasury obligations,
    4.25% to 6.125% due 11/15/03 to 08/15/29 with an aggregate market value at
    08/31/99 of $229,500,304.
(e) Open repurchase agreement entered into 08/27/97; however, either party may
    terminate the agreement upon demand. Interest rates, par and collateral are
    redetermined daily. Collateralized by $451,335,000 U.S. Treasury
    obligations, 0% to 8.75% due 07/20/00 to 11/15/26 with an aggregate market
    value at 08/31/99 of $153,430,781.
(f) Term repurchase agreement entered into 07/28/99; however, either party may
    terminate the agreement upon demand. Interest rates, par and collateral are
    redetermined daily. Collateralized by $153,000,000 U.S Treasury
    obligations, 4.50% to 10.625% due 05/15/00 to 08/15/17 with an aggregate
    market value at 08/31/99 of $204,012,877.
(g) Repurchase agreement entered into 08/31/99 with a maturing value of
    $225,033,938. Collateralized by $225,851,000 U.S. Treasury obligations, 0%
    to 3.875% due 09/02/99 to 04/15/29 with an aggregate market value at
    08/31/99 of $229,500,787.
(h) Repurchase agreement entered into 08/31/99 with a maturing value of
    $225,033,938. Collateralized by $223,219,000 U.S. Treasury obligations, 0%
    to 7.25% due 09/15/99 to 08/15/26 with an aggregate market value at
    08/31/99 of $229,504,040.
(i) Term repurchase agreement entered into 07/27/99; however, either party may
    terminate the agreement upon demand. Interest rates, par and collateral are
    redetermined daily. Collateralized by $445,674,874 U.S Treasury
    obligations, 0% to 12.00% due 11/15/99 to 11/15/27 with an aggregate market
    value at 08/31/99 of $206,048,641.
(j) Open repurchase agreement entered into 07/29/98; however, either party may
    terminate the agreement upon demand. Interest rates, par and collateral are
    redetermined daily. Collateralized by $795,187,000 U.S. Treasury
    obligations, 3.375% to 8.00% due 08/31/00 to 11/15/21 with an aggregate
    market value at 08/31/99 of $816,000,276.
(k) Repurchase agreement entered into 08/31/99 with a maturing value of
    $225,033,938. Collateralized by $169,934,000 U.S. Treasury obligations,
    6.875% to 12.50% due 08/15/14 to 08/15/25 with an aggregate market value at
    08/31/99 of $229,503,106.
(l) Repurchase agreement entered into 08/31/99 with a maturing value of
    $750,113,125. Collateralized by $746,935,000 U.S. Treasury obligations,
    6.00% to 7.00% due 08/15/04 to 07/15/06 with an aggregate market value at
    08/31/99 of $765,177,675.
(m) Repurchase agreement entered into 08/31/99 with a maturing value of
    $500,075,417. Collateralized by $439,557,000 U.S. Treasury obligations,
    4.50% to 12.50% due 09/30/99 to 08/15/26 with an aggregate market value at
    08/31/99 of $510,297,171.
(n) Repurchase agreement entered into 08/31/99 with a maturing value of
    $225,033,938. Collateralized by $230,660,000 U.S. Treasury obligations,
    5.125% due 08/31/00 with a market value at 08/31/99 of $229,760,426.
(o) Term repurchase agreement entered into 08/19/99; however, either party may
    terminate the agreement upon demand. Interest rates, par and collateral are
    redetermined daily. Collateralized by $90,430,000 U.S Treasury obligations,
    7.50% due 11/15/16 with a market value at 08/31/99 of $102,000,601.
(p) Joint repurchase agreement entered into 08/31/99 with a maturing value of
    $500,075,278. Collateralized by $500,003,334 U.S. Treasury obligations,
    6.50% to 9.125% due 05/15/18 to 11/15/26 with an aggregate market value at
    08/31/99 of $510,003,412.
(q) Also represents cost for federal income tax purposes.

See Notes to Financial Statements.

                                     FS-3
<PAGE>   55

STATEMENT OF ASSETS AND LIABILITIES
August 31, 1999

ASSETS:

Investments, excluding repurchase agreements, at value
 (amortized cost)                                         $  938,245,314
- ------------------------------------------------------------------------
Repurchase agreements                                      4,272,630,039
- ------------------------------------------------------------------------
Interest receivable                                           13,668,357
- ------------------------------------------------------------------------
Investment for deferred compensation plan                        101,152
- ------------------------------------------------------------------------
Other assets                                                     172,580
- ------------------------------------------------------------------------
  Total assets                                             5,224,817,442
- ------------------------------------------------------------------------

LIABILITIES:

Payables for:
 Dividends                                                    20,194,469
- ------------------------------------------------------------------------
 Deferred compensation                                           101,152
- ------------------------------------------------------------------------
Accrued administrative services fees                              24,787
- ------------------------------------------------------------------------
Accrued advisory fees                                            247,796
- ------------------------------------------------------------------------
Accrued distribution fees                                        396,227
- ------------------------------------------------------------------------
Accrued transfer agent fees                                        2,629
- ------------------------------------------------------------------------
Accrued trustees' fees                                             4,200
- ------------------------------------------------------------------------
Accrued operating expenses                                        99,076
- ------------------------------------------------------------------------
  Total liabilities                                           21,070,336
- ------------------------------------------------------------------------
NET ASSETS                                                $5,203,747,106
========================================================================

NET ASSETS:

Institutional Class                                       $3,164,199,019
========================================================================
Private Investment Class                                  $  415,184,467
========================================================================
Personal Investment Class                                 $  284,932,336
========================================================================
Cash Management Class                                     $  860,354,479
========================================================================
Reserve Class                                             $  119,976,218
========================================================================
Resource Class                                            $  359,100,587
========================================================================

SHARES OF BENEFICIAL INTEREST, $.01 PAR VALUE PER SHARE:

Institutional Class                                        3,163,983,313
========================================================================
Private Investment Class                                     415,165,788
========================================================================
Personal Investment Class                                    284,906,884
========================================================================
Cash Management Class                                        860,290,642
========================================================================
Reserve Class                                                119,973,330
========================================================================
Resource Class                                               359,071,030
========================================================================

NET ASSET VALUE PER SHARE:

Net asset value, offering and redemption price per share  $         1.00
========================================================================

See Notes to Financial Statements.

                                     FS-4
<PAGE>   56

STATEMENT OF OPERATIONS
For the year ended August 31, 1999

INVESTMENT INCOME:

Interest income                                       $261,703,046
- -------------------------------------------------------------------

EXPENSES:

Advisory fees                                            3,072,316
- -------------------------------------------------------------------
Custodian fees                                             196,425
- -------------------------------------------------------------------
Administrative services fees                               179,471
- -------------------------------------------------------------------
Trustees' fees and expenses                                 51,955
- -------------------------------------------------------------------
Transfer agent fees                                        594,299
- -------------------------------------------------------------------
Distribution fees (Note 2)                               6,590,154
- -------------------------------------------------------------------
Other                                                      500,054
- -------------------------------------------------------------------
  Total expenses                                        11,184,674
- -------------------------------------------------------------------
Less: Fee waivers                                       (2,048,089)
- -------------------------------------------------------------------
  Net expenses                                           9,136,585
- -------------------------------------------------------------------
Net investment income                                  252,566,461
- -------------------------------------------------------------------
Net realized gain on sales of investments                  233,481
- -------------------------------------------------------------------
Net increase in net assets resulting from operations  $252,799,942
===================================================================

STATEMENT OF CHANGES IN NET ASSETS
For the years ended ended August 31, 1999 and 1998

                                                   1999            1998
                                              --------------  --------------

OPERATIONS:

 Net investment income                        $  252,566,461  $  282,365,404
- -----------------------------------------------------------------------------
 Net realized gain on sales of investments           233,481          17,887
- -----------------------------------------------------------------------------
  Net increase in net assets resulting from
   operations                                    252,799,942     282,383,291
- -----------------------------------------------------------------------------
Distributions to shareholders from net
 investment income:
  Institutional Class                           (154,878,876)   (171,162,611)
- -----------------------------------------------------------------------------
  Private Investment Class                       (16,111,371)    (20,105,302)
- -----------------------------------------------------------------------------
  Personal Investment Class                      (16,331,172)    (18,031,165)
- -----------------------------------------------------------------------------
  Cash Management Class                          (46,789,257)    (55,954,060)
- -----------------------------------------------------------------------------
  Reserve Class                                   (1,139,360)             --
- -----------------------------------------------------------------------------
  Resource Class                                 (17,316,425)    (17,112,266)
- -----------------------------------------------------------------------------
Distributions to shareholders from net
 realized gains:
  Institutional Class                               (432,034)             --
- -----------------------------------------------------------------------------
  Private Investment Class                           (43,761)             --
- -----------------------------------------------------------------------------
  Personal Investment Class                          (47,801)             --
- -----------------------------------------------------------------------------
  Cash Management Class                             (126,796)             --
- -----------------------------------------------------------------------------
  Resource Class                                     (49,581)             --
- -----------------------------------------------------------------------------
Share transactions-net (See Note 4)               59,979,434    (116,572,228)
- -----------------------------------------------------------------------------
  Net increase (decrease) in net assets           59,512,942    (116,554,341)
- -----------------------------------------------------------------------------

NET ASSETS:

  Beginning of period                          5,144,234,164   5,260,788,505
- -----------------------------------------------------------------------------
  End of period                               $5,203,747,106  $5,144,234,164
=============================================================================

NET ASSETS CONSIST OF:

  Shares of beneficial interest               $5,203,390,987  $5,143,411,553
- -----------------------------------------------------------------------------
  Undistributed net realized gain on sales of
   investments                                       356,119         822,611
- -----------------------------------------------------------------------------
                                              $5,203,747,106  $5,144,234,164
=============================================================================

See Notes to Financial Statements.

                                     FS-5
<PAGE>   57

NOTES TO FINANCIAL STATEMENTS
August 31, 1999

NOTE 1-SIGNIFICANT ACCOUNTING POLICIES

Short-Term Investments Trust (the "Fund") is registered under the Investment
Company Act of 1940, as amended, as an open-end series, diversified management
investment company. The Fund is organized as a Delaware business trust
consisting of three different portfolios, each of which offers separate series
of shares: the Treasury Portfolio, the Government & Agency Portfolio and the
Treasury TaxAdvantage Portfolio. Information presented in these financial
statements pertains only to the Treasury Portfolio (the "Portfolio"), with the
assets, liabilities and operations of each portfolio being accounted for
separately. The Portfolio currently offers six different classes of shares: the
Institutional Class, the Private Investment Class, the Personal Investment
Class, the Cash Management Class, the Reserve Class and the Resource Class.
Matters affecting each class are voted on exclusively by the shareholders of
each class. The Portfolio is a money market fund whose investment objective is
the maximization of current income to the extent consistent with the
preservation of capital and the maintenance of liquidity.
 The preparation of financial statements in conformity with generally accepted
accounting principles requires management to make estimates and assumptions
that affect the reported amounts of assets and liabilities at the date of the
financial statements and the reported amounts of revenues and expenses during
the reporting period. Actual results could differ from those estimates. The
following is a summary of significant accounting policies followed by the
Portfolio in the preparation of its financial statements.
A. Security Valuations - The Portfolio's securities are valued on the basis of
   amortized cost which approximates market value. This method values a
   security at its cost on the date of purchase and thereafter assumes a
   constant amortization to maturity of any discount or premium.
B. Securities Transactions, Investment Income and Distributions - Securities
   transactions are accounted for on a trade date basis. Realized gains or
   losses are computed on the basis of specific identification of the
   securities sold. Interest income, adjusted for amortization of premiums and
   discounts on investments, is accrued daily. Dividends to shareholders are
   declared daily and are paid on the first business day of the following
   month.
C. Federal Income Taxes - The Portfolio intends to comply with the requirements
   of the Internal Revenue Code necessary to qualify as a regulated investment
   company and, as such, will not be subject to federal income taxes on
   otherwise taxable income (including net realized capital gains) which is
   distributed to shareholders. Therefore, no provision for federal income
   taxes is recorded in the financial statements.
D. Expenses - Distribution expenses directly attributable to a class of shares
   are charged to that class' operations. All other expenses are allocated
   among the classes.

NOTE 2-ADVISORY FEES AND OTHER TRANSACTIONS WITH AFFILIATES

The Fund has entered into a master investment advisory agreement with A I M
Advisors, Inc. ("AIM"). Under the terms of the master investment advisory
agreement, AIM receives a monthly fee with respect to the Portfolio calculated
by applying a monthly rate, based upon the following annual rates, to the
average daily net assets of the Portfolio:

Net Assets                         RATE
- ----------------------------------------
First $300 million                 0.15%
- ----------------------------------------
Over $300 million to $1.5 billion  0.06%
- ----------------------------------------
Over $1.5 billion                  0.05%
- ----------------------------------------

                                     FS-6
<PAGE>   58

 The Fund, pursuant to a master administrative services agreement with AIM, has
agreed to pay AIM for certain administrative costs incurred in providing
accounting services to the Fund. During the year ended August 31, 1999, AIM was
paid $179,471 for such services.
 The Fund, pursuant to a transfer agency and service agreement, has agreed to
pay A I M Fund Services, Inc. ("AFS") a fee for providing transfer agent and
shareholder services to the Fund. During the year ended August 31, 1999, AFS
was paid $477,417 for such services.
 Under the terms of a master distribution agreement between Fund Management
Company ("FMC") and the Fund, FMC acts as the exclusive distributor of the
Fund's shares. The Fund has adopted a master distribution plan (the "Plan")
pursuant to Rule 12b-1 under the 1940 Act with respect to the Private
Investment Class, the Personal Investment Class, the Cash Management Class, the
Reserve Class and the Resource Class of the Portfolio. The Plan provides that
the Private Investment Class, the Personal Investment Class, the Cash
Management Class, the Reserve Class and the Resource Class pay up to a 0.50%,
0.75%, 0.10%, 1.00%, and 0.20%, respectively, maximum annual rate of the
average daily net assets attributable to such class. Of this amount, the Fund
may pay an asset-based sales charge to FMC and the Fund may pay a service fee
of (a) 0.25% of the average daily net assets of each of the Private Investment
Class, Personal Investment Class, and the Reserve Class, (b) 0.10% of the
average daily net assets of the Cash Management Class and (c) 0.20% of the
average daily net assets of the Resource Class, to selected banks, broker-
dealers and other financial institutions who offer continuing personal
shareholder services to their customers who purchase and own shares of the
Private Investment Class, the Personal Investment Class, the Cash Management
Class, the Reserve Class or the Resource Class. Any amounts not paid as a
service fee under such Plan would constitute an asset-based sales charge. The
Plan also imposes a cap on the total amount of sales charges, including asset-
based sales charges, that may be paid by the Portfolio with respect to each
class. During the year ended August 31, 1999, the Private Investment Class, the
Personal Investment Class, the Cash Management Class, the Reserve Class and the
Resource Class paid $1,063,328, $1,878,076, $783,278, $226,595 and $590,788,
respectively, as compensation under the Plan. FMC waived fees of $2,048,089 for
the same period. Certain officers and trustees of the Trust are officers of
AIM, FMC and AFS.
 During the year ended August 31, 1999, the Portfolio paid legal fees of
$13,465 for services rendered by Kramer, Levin, Naftalis & Frankel LLP as
counsel to the Board of Trustees. A member of that firm is a trustee of the
Fund.

NOTE 3-TRUSTEES' FEES

Trustees' fees represent remuneration paid to trustees who are not an
"interested person" of AIM. The Fund may invest trustees' fees, if so elected
by a trustee, in mutual fund shares in accordance with a deferred compensation
plan.

                                     FS-7
<PAGE>   59

NOTE 4-SHARE INFORMATION

Changes in shares outstanding during the years ended August 31, 1999 and 1998
were as follows:
<TABLE>
<CAPTION>

                                      1999                              1998
                         --------------------------------  --------------------------------
                             SHARES           AMOUNT           SHARES           AMOUNT
                         ---------------  ---------------  ---------------  ---------------
<S>                       <C>             <C>               <C>             <C>
Sold:
  Institutional Class     18,697,189,201  $18,697,189,201   18,385,087,568  $18,385,087,568
- -------------------------------------------------------------------------------------------
  Private Investment
   Class                   1,543,792,773    1,543,792,773    1,991,337,616    1,991,337,616
- -------------------------------------------------------------------------------------------
  Personal Investment
   Class                   3,783,262,789    3,783,262,789    3,949,434,631    3,949,434,631
- -------------------------------------------------------------------------------------------
  Cash Management Class    6,593,996,488    6,593,996,488    6,742,292,291    6,742,292,291
- -------------------------------------------------------------------------------------------
  Reserve Class*             339,249,182      339,249,182               --               --
- -------------------------------------------------------------------------------------------
  Resource Class           2,625,595,247    2,625,595,247    2,712,585,402    2,712,585,402
- -------------------------------------------------------------------------------------------
Issued as reinvestment
 of dividends:
  Institutional Class         35,404,120       35,404,120       34,740,376       34,740,376
- -------------------------------------------------------------------------------------------
  Private Investment
   Class                       5,531,007        5,531,007        5,517,795        5,517,795
- -------------------------------------------------------------------------------------------
  Personal Investment
   Class                      14,908,717       14,908,717       16,025,048       16,025,048
- -------------------------------------------------------------------------------------------
  Cash Management Class       18,450,756       18,450,756       20,427,201       20,427,201
- -------------------------------------------------------------------------------------------
  Reserve Class*                 740,689          740,689               --               --
- -------------------------------------------------------------------------------------------
  Resource Class              16,749,204       16,749,204       15,915,270       15,915,270
- -------------------------------------------------------------------------------------------
Reacquired:
  Institutional Class    (18,556,477,426) (18,556,477,426) (18,839,453,624) (18,839,453,624)
- -------------------------------------------------------------------------------------------
  Private Investment
   Class                  (1,494,418,811)  (1,494,418,811)  (2,099,963,668)  (2,099,963,668)
- -------------------------------------------------------------------------------------------
  Personal Investment
   Class                  (3,919,007,542)  (3,919,007,542)  (3,882,639,209)  (3,882,639,209)
- -------------------------------------------------------------------------------------------
  Cash Management Class   (6,685,798,097)  (6,685,798,097)  (6,658,189,744)  (6,658,189,744)
- -------------------------------------------------------------------------------------------
  Reserve Class*            (220,016,541)    (220,016,541)              --               --
- -------------------------------------------------------------------------------------------
  Resource Class          (2,739,172,322)  (2,739,172,322)  (2,509,689,181)  (2,509,689,181)
- -------------------------------------------------------------------------------------------
Net increase (decrease)       59,979,434  $    59,979,434     (116,572,228) $  (116,572,228)
===========================================================================================
</TABLE>

* The Reserve Class commenced sales on January 4, 1999.

                                     FS-8
<PAGE>   60

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Cash Management
Class outstanding for each of the years in the five-year period ended August
31, 1999.

                              1999         1998      1997      1996     1995
                            --------     --------  --------  --------  -------
Net asset value, beginning
 of period                  $   1.00     $   1.00  $   1.00  $   1.00  $  1.00
- --------------------------  --------     --------  --------  --------  -------
Income from investment
 operations:
  Net investment income         0.05         0.05      0.05      0.05     0.05
- --------------------------  --------     --------  --------  --------  -------
Less distributions:
  Dividends from net
   investment income           (0.05)       (0.05)    (0.05)    (0.05)   (0.05)
- --------------------------  --------     --------  --------  --------  -------
Net asset value, end of
 period                     $   1.00     $   1.00  $   1.00  $   1.00  $  1.00
==========================  ========     ========  ========  ========  =======
Total return                    4.89%        5.56%     5.39%     5.48%    5.57%
==========================  ========     ========  ========  ========  =======
Ratios/supplemental data:
Net assets, end of period
 (000s omitted)             $860,354     $933,791  $829,243  $789,627  $81,219
==========================  ========     ========  ========  ========  =======
Ratio of expenses to
 average net assets(a)          0.17%(b)     0.17%     0.17%     0.17%    0.18%
==========================  ========     ========  ========  ========  =======
Ratio of net investment
 income to average net
 assets(c)                      4.77%(b)     5.42%     5.25%     5.25%    5.42%
==========================  ========     ========  ========  ========  =======
(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.19%, 0.19%, 0.19%, 0.19% and 0.20% for the periods 1999-1995,
    respectively.
(b) Ratios based on average net assets of $979,097,144.
(c) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.75%, 5.40%, 5.24%, 5.23% and 5.40% for the periods
    1999-1995, respectively.

                                      FS-9

<PAGE>   61

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Institutional Class
outstanding for each of the years in the five-year period ended August 31,
1999.
<TABLE>
<CAPTION>

                            1999           1998        1997        1996        1995
                         ----------     ----------  ----------  ----------  ----------
<S>                      <C>            <C>         <C>         <C>         <C>
Net asset value,
 beginning of period     $     1.00     $     1.00  $     1.00  $     1.00  $     1.00
- -----------------------  ----------     ----------  ----------  ----------  ----------
Income from investment
 operations:
  Net investment income        0.05           0.05        0.05        0.05        0.06
- -----------------------  ----------     ----------  ----------  ----------  ----------
Less distributions:
  Dividends from net
   investment income          (0.05)         (0.05)      (0.05)      (0.05)      (0.06)
- -----------------------  ----------     ----------  ----------  ----------  ----------
Net asset value, end of
 period                  $     1.00     $     1.00  $     1.00  $     1.00  $     1.00
=======================  ==========     ==========  ==========  ==========  ==========
Total return                   4.97%          5.64%       5.47%       5.57%       5.66%
=======================  ==========     ==========  ==========  ==========  ==========
Ratios/supplemental
 data:
Net assets, end of
 period (000s omitted)   $3,164,199     $2,988,375  $3,408,010  $2,335,441  $2,669,637
=======================  ==========     ==========  ==========  ==========  ==========
Ratio of expenses to
 average net assets            0.09%(a)       0.08%       0.09%       0.09%       0.10%
=======================  ==========     ==========  ==========  ==========  ==========
Ratio of net investment
 income to average net
 assets                        4.85%(a)       5.50%       5.35%       5.43%       5.53%
=======================  ==========     ==========  ==========  ==========  ==========
(a)Ratios based on average net assets of $3,197,910,489.
</TABLE>

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

                                    FS-10
<PAGE>   62

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Personal Investment
Class outstanding for each of the years in the five-year period ended August
31, 1999.

                             1999         1998      1997      1996      1995
                           --------     --------  --------  --------  --------
Net asset value,
 beginning of period       $   1.00     $   1.00  $   1.00  $   1.00  $   1.00
- -------------------------  --------     --------  --------  --------  --------
Income from investment
 operations:
  Net investment income        0.04         0.05      0.05      0.05      0.05
- -------------------------  --------     --------  --------  --------  --------
Less distributions:
  Dividends from net
   investment income          (0.04)       (0.05)    (0.05)    (0.05)    (0.05)
- -------------------------  --------     --------  --------  --------  --------
Net asset value, end of
 period                    $   1.00     $   1.00  $   1.00  $   1.00  $   1.00
=========================  ========     ========  ========  ========  ========
Total return                   4.45%        5.12%     4.95%     5.04%     5.13%
=========================  ========     ========  ========  ========  ========
Ratios/supplemental data:
Net assets, end of period
 (000s omitted)            $284,932     $405,801  $322,971  $192,947  $114,527
=========================  ========     ========  ========  ========  ========
Ratio of expenses to
 average net assets(a)         0.59%(b)     0.58%     0.60%     0.59%     0.60%
=========================  ========     ========  ========  ========  ========
Ratio of net investment
 income to average net
 assets(c)                     4.35%(b)     5.01%     4.85%     4.91%     5.03%
=========================  ========     ========  ========  ========  ========
(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.84%, 0.83%, 0.86%, 0.92% and 0.90% for the periods 1999-1995,
    respectively.
(b) Ratios based on average net assets of $375,615,292.
(c) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.10%, 4.76%, 4.59%, 4.58% and 4.73% for the periods
    1999-1995, respectively.

                                      FS-11
<PAGE>   63

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Private Investment
Class outstanding for each of the years in the five-year period ended August
31, 1999.

                             1999         1998      1997      1996      1995
                           --------     --------  --------  --------  --------
Net asset value,
 beginning of period       $   1.00     $   1.00  $   1.00  $   1.00  $   1.00
- -------------------------  --------     --------  --------  --------  --------
Income from investment
 operations:
  Net investment income        0.05         0.05      0.05      0.05      0.05
- -------------------------  --------     --------  --------  --------  --------
Less distributions:
  Dividends from net
   investment income          (0.05)       (0.05)    (0.05)    (0.05)    (0.05)
- -------------------------  --------     --------  --------  --------  --------
Net asset value, end of
 period                    $   1.00     $   1.00  $   1.00  $   1.00  $   1.00
=========================  ========     ========  ========  ========  ========
Total return                   4.66%        5.33%     5.16%     5.25%     5.34%
=========================  ========     ========  ========  ========  ========
Ratios/supplemental data:
Net assets, end of period
 (000s omitted)            $415,184     $360,307  $463,441  $352,537  $394,585
=========================  ========     ========  ========  ========  ========
Ratio of expenses to
 average net assets(a)         0.39%(b)     0.38%     0.39%     0.39%     0.40%
=========================  ========     ========  ========  ========  ========
Ratio of net investment
 income to average net
 assets(c)                     4.55%(b)     5.20%     5.05%     5.14%     5.23%
=========================  ========     ========  ========  ========  ========
(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.59%, 0.58%, 0.59%, 0.59% and 0.60% for the periods 1999-1995,
    respectively.
(b) Ratios based on average net assets of $354,442,723.
(c) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.35%, 5.00%, 4.85%, 4.94% and 5.03% for the periods
    1999-1995, respectively.

                                      FS-12
<PAGE>   64

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Reserve Class
outstanding during the period January 4, 1999 (date sales commenced) through
August 31, 1999.

                                                           1999
                                                         --------
Net asset value, beginning of period                     $   1.00
- -------------------------------------------------------  --------
Income from investment operations:
  Net investment income                                      0.03
- -------------------------------------------------------  --------
Less distributions:
  Dividends from net investment income                      (0.03)
- -------------------------------------------------------  --------
Net asset value, end of period                           $   1.00
=======================================================  ========
Total return(a)                                              2.63%
=======================================================  ========
Ratios/supplemental data:
Net assets, end of period (000s omitted)                 $119,976
=======================================================  ========
Ratio of expenses to average net assets(b)                   0.89%(c)
=======================================================  ========
Ratio of net investment income to average net assets(d)      2.09%(c)
=======================================================  ========
(a) Not annualized for periods less than one year.
(b) After fee waivers and/or expense reimbursements. Ratio of expenses to
    average net assets prior to fee waivers and/or expense reimbursements was
    1.09%.
(c) Ratios based on average net assets of $28,324,369.
(d) After fee waivers and/or expense reimbursements. Ratio of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements was 1.89%.

                                     FS-13
<PAGE>   65

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Resource Class
outstanding for each of the years in the three-year period ended August 31,
1999 and the period March 12, 1996 (date sales commenced) through August 31,
1996.

                                     1999         1998      1997     1996
                                   --------     --------  --------  -------
Net asset value, beginning of
 period                            $   1.00     $   1.00  $   1.00  $  1.00
- ---------------------------------  --------     --------  --------  -------
Income from investment
 operations:
  Net investment income                0.05         0.05      0.05     0.03
- ---------------------------------  --------     --------  --------  -------
Less distributions:
  Dividends from net investment
   income                             (0.05)       (0.05)    (0.05)   (0.03)
=================================  ========     ========  ========  =======
Net asset value, end of period     $   1.00     $   1.00  $   1.00  $  1.00
=================================  ========     ========  ========  =======
Total return                           4.80%        5.47%     5.30%    2.43%
=================================  ========     ========  ========  =======
Ratios/supplemental data:
Net assets, end of period (000s
 omitted)                          $359,101     $455,961  $237,123  $33,339
=================================  ========     ========  ========  =======
Ratio of expenses to average net
 assets(a)                             0.25%(b)     0.24%     0.25%    0.25%(c)
=================================  ========     ========  ========  =======
Ratio of net investment income to
 average net assets(d)                 4.69%(b)     5.34%     5.19%    5.07%(c)
=================================  ========     ========  ========  =======
(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursement were
    0.29%, 0.28%, 0.29% and 0.29% (annualized) for the periods 1999-1996,
    respectively.
(b) Ratios based on average net assets of $369,242,180.
(c) Annualized
(d) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursement were 4.65%, 5.30%, 5.15% and 5.03% (annualized) for the
    periods 1999-1996, respectively.

                                      FS-14
<PAGE>   66
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------


OBTAINING ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------

More information may be obtained free of charge upon request. The Statement of
Additional Information (SAI), a current version of which is on file with the
Securities and Exchange Commission (SEC), contains more details about the fund
and is incorporated by reference into the prospectus (is legally a part of this
prospectus). Annual and semiannual reports to shareholders contain additional
information about the fund's investments. The fund's annual report also
discusses the market conditions and investment strategies that significantly
affected the fund's performance during its last fiscal year.

  If you have questions about this fund, another fund in The AIM Family of
Funds--Registered Trademark-- or your account, or wish to obtain free copies of
the fund's current SAI or annual or semiannual reports, please contact us

- ---------------------------------------------------------
<TABLE>
<S>                          <C>
BY MAIL:                     A I M Fund Services, Inc.
                             P. O. Box 4497
                             Houston, TX 77210-4497

BY TELEPHONE:                (800) 659-1005

BY E-MAIL:                   [email protected]

ON THE INTERNET:             http://www.aimfunds.com
                             (prospectuses and annual
                             and semiannual reports
                             only)
</TABLE>
- ---------------------------------------------------------

You also can review and obtain copies of the fund's SAI, reports and other
information at the SEC's Public Reference Room in Washington, DC; on the EDGAR
database on the SEC's Internet website (http://www.sec.gov); or, after paying a
duplication fee, by sending a letter to the SEC's Public Reference Section,
Washington, DC 20549-0102 or by sending an electronic mail request to
[email protected]. Please call the SEC at 1-202-942-8090 for information about
the Public Reference Room.

- -----------------------------------
 Treasury Portfolio
 SEC 1940 Act file number: 811-2729
- -----------------------------------

[AIM LOGO APPEARS HERE]      www.aimfunds.com             INVEST WITH DISCIPLINE
                                                        --Registered Trademark--
<PAGE>   67
        TREASURY PORTFOLIO

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

        PERSONAL INVESTMENT CLASS
        Treasury Portfolio seeks to maximize current income consistent with the
        preservation of capital and the maintenance of liquidity.

        PROSPECTUS
        DECEMBER 17, 1999

                                       This prospectus contains important
                                       information about the Personal
                                       Investment Class of the fund. Please
                                       read it before investing and keep it
                                       for future reference.

                                       As with all other mutual fund
                                       securities, the Securities and
                                       Exchange Commission has not approved
                                       or disapproved these securities or
                                       determined whether the information
                                       in this prospectus is adequate or
                                       accurate. Anyone who tells you
                                       otherwise is committing a crime.

                                       There can be no assurance that the
                                       fund will be able to maintain a
                                       stable net asset value of $1.00 per
                                       share.

        [AIM LOGO APPEARS HERE]                  INVEST WITH DISCIPLINE

                                                --Registered Trademark--
<PAGE>   68
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

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

<TABLE>
<S>                                       <C>

INVESTMENT OBJECTIVE AND STRATEGIES           1

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

PRINCIPAL RISKS OF INVESTING IN THE
  FUND                                        1

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

PERFORMANCE INFORMATION                       2

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

Annual Total Returns                          2

Performance Table                             2

FEE TABLE AND EXPENSE EXAMPLE                 3

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

Fee Table                                     3

Expense Example                               3

FUND MANAGEMENT                               4

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

The Advisor                                   4

Advisor Compensation                          4

OTHER INFORMATION                             4

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

Suitability for Investors                     4

Dividends and Distributions                   4

FINANCIAL HIGHLIGHTS                          5

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

SHAREHOLDER INFORMATION                     A-1

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

Distribution and Service (12b-1) Fees       A-1

Purchasing Shares                           A-1

Redeeming Shares                            A-1

Pricing of Shares                           A-2

Taxes                                       A-2

OBTAINING ADDITIONAL INFORMATION     Back Cover

- - - - - - - - - - - - - - - - - - - - - - - - - -
</TABLE>

The AIM Family of Funds, The AIM Family of Funds and Design (i.e., the AIM
logo), AIM and Design, AIM, AIM LINK, AIM Institutional Funds, aimfunds.com, La
Familia AIM de Fondos, La Familia AIM de Fondos and Design and Invest with
Discipline are registered service marks and AIM Bank Connection, AIM Funds, AIM
Funds and Design, AIM Internet Connect and AIM Investor are service marks of
A I M Management Group Inc.

No dealer, salesperson or any other person has been authorized to give any
information or to make any representations other than those contained in this
prospectus, and you should not rely on such other information or
representations.
<PAGE>   69
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

INVESTMENT OBJECTIVE AND STRATEGIES
- --------------------------------------------------------------------------------

The fund's investment objective is to maximize current income consistent with
the preservation of capital and the maintenance of liquidity.

  The fund attempts to meet this objective by investing in direct obligations of
the U.S. Treasury, including bills, notes and bonds, and repurchase agreements
secured by those obligations. The fund will maintain a weighted average maturity
of 90 days or less. The fund invests in compliance with Rule 2a-7 under the
Investment Company Act of 1940.

  The portfolio managers focus on securities they believe have favorable
prospects for current income consistent with the preservation of capital and the
maintenance of liquidity. The portfolio managers usually hold portfolio
securities to maturity, but may sell a particular security when they deem it
advisable, such as when any of the factors above materially changes.

  In anticipation of or in response to adverse market conditions, for cash
management purposes, or for defensive purposes, the fund may temporarily hold
all or a portion of its assets in cash or shares of affiliated money market
funds. As a result, the fund may not achieve its investment objective.

PRINCIPAL RISKS OF INVESTING IN THE FUND
- --------------------------------------------------------------------------------

An investment in the fund is not a deposit of a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. Although the fund seeks to preserve the value of your investment at
$1.00 per share, it is possible to lose money by investing in the fund.
Additionally, the fund's yield will vary as the short-term securities in its
portfolio mature and the proceeds are reinvested in securities with different
interest rates.

  The following factors could reduce the fund's income and/or share price:

- - sharply rising interest rates; and

- - downgrades of credit ratings or defaults of any of the fund's holdings.

  If the seller of a repurchase agreement in which the fund invests defaults on
its obligation or declares bankruptcy, the fund may experience delays in selling
the securities underlying the repurchase agreement. As a result, the fund may
incur losses arising from decline in the value of those securities, reduced
levels of income and expenses of enforcing its rights.

  The value of your shares could be adversely affected if the computer systems
used by the fund's investment advisor and the fund's other service providers are
unable to distinguish the year 2000 from the year 1900.

  The fund's investment advisor and independent technology consultants are
working to avoid year 2000-related problems in its systems and to obtain
assurances that other service providers are taking similar steps. Year 2000
problems may also affect issuers in whose securities the fund invests.

                                        1
<PAGE>   70
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
The bar chart and table shown below provide an indication of the risks of
investing in the fund. The fund's past performance is not necessarily an
indication of its future performance.

ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
The following bar chart shows changes in the performance of the Personal
Investment Class shares from year to year. Personal Investment Class shares are
not subject to sales loads.

                                    [GRAPH]

<TABLE>
<CAPTION>
                                          Annual
Year Ended                                Total
December 31                               Return
- -----------                               ------
<S>                                       <C>
1992....................................   3.43%
1993....................................   2.68%
1994....................................   3.63%
1995....................................   5.42%
1996....................................   4.88%
1997....................................   5.04%
1998....................................   4.95%
</TABLE>

The Personal Investment Class shares' year-to-date total return as of September
30, 1999 was 3.26%.

  During the periods shown in the bar chart, the highest quarterly return was
1.37% (quarter ended June 30, 1995) and the lowest quarterly return was 0.66%
(quarter ended June 30, 1993).

PERFORMANCE TABLE

The following performance table reflects the performance of Personal Investment
Class shares over the periods indicated.

<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS
- ------------------------------------------------------------------------------------------------------
(for the periods ended                                                          SINCE      INCEPTION
December 31, 1998)                               1 YEAR   5 YEARS   10 YEARS   INCEPTION     DATE
- ------------------------------------------------------------------------------------------------------
<S>                                              <C>      <C>       <C>        <C>         <C>
Personal Investment Class                         4.95%    4.78%        --       4.32%      08/08/91
- ------------------------------------------------------------------------------------------------------
</TABLE>

Personal Investment Class shares' seven-day yield on December 31, 1998 was
4.31%. For the current seven-day yield, call (800) 877-4744.

                                        2
<PAGE>   71
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

FEE TABLE AND EXPENSE EXAMPLE
- --------------------------------------------------------------------------------

FEE TABLE

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

<TABLE>
<CAPTION>
SHAREHOLDER FEES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(fees paid directly from           PERSONAL
your investment)               INVESTMENT CLASS
- -----------------------------------------------
<S>                            <C>
Maximum Sales Charge (Load)
Imposed on Purchases
(as a percentage of
offering price)                       None

Maximum Deferred
Sales Charge (Load)
(as a percentage of
original purchase
price or redemption
proceeds, whichever is less)          None
- -----------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(expenses that are deducted        PERSONAL
from fund assets)              INVESTMENT CLASS
- -----------------------------------------------
<S>                            <C>
Management Fees                      0.06%
Distribution and/or
Service (12b-1) Fees                 0.75
Other Expenses                       0.03
Total Annual Fund
Operating Expenses                   0.84
Fee Waiver(1)                        0.25
Net Expenses                         0.59
- -----------------------------------------------
</TABLE>

(1) The distributor has contractually agreed to waive 0.25% of the Rule 12b-1
    distribution plan fee.
You should also consider the effect of any account fees charged by the financial
institution managing the account.
  As a result of 12b-1 fees, long-term shareholders in the fund may pay more
than the maximum permitted initial sales charge.

EXPENSE EXAMPLE

This example is intended to help you compare the costs of investing in the
Personal Investment Class of 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 gross operating expenses remain the same. To the extent fees are waived
or expenses are reimbursed, the expenses will be lower. Although your actual
returns and costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
                     1 YEAR   3 YEARS   5 YEARS   10 YEARS
- ----------------------------------------------------------
<S>                  <C>      <C>       <C>       <C>
Personal Investment
Class                 $86      $268      $466      $1,037
- ----------------------------------------------------------
</TABLE>

                                        3
<PAGE>   72
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

FUND MANAGEMENT
- --------------------------------------------------------------------------------

THE ADVISOR

A I M Advisors, Inc. (the advisor) serves as the fund's investment advisor and
is responsible for its day-to-day management. The advisor is located at 11
Greenway Plaza, Suite 100, Houston, Texas 77046-1173. The advisor supervises all
aspects of the fund's operations and provides investment advisory services to
the fund, including obtaining and evaluating economic, statistical and financial
information to formulate and implement investment programs for the fund.

  The advisor has acted as an investment advisor since its organization in 1976.
Today, the advisor, together with its subsidiaries, advises or manages over 125
investment portfolios, including the fund, encompassing a broad range of
investment objectives.

ADVISOR COMPENSATION

During the fiscal year ended August 31, 1999, the advisor received compensation
of 0.06% of average daily net assets.

OTHER INFORMATION
- --------------------------------------------------------------------------------

SUITABILITY FOR INVESTORS

The Personal Investment Class of the fund is intended for use primarily by
customers of banks, certain broker-dealers and other institutions
(institutions). Individuals, corporations, partnerships and other businesses
that maintain qualified accounts at an institution may invest in shares of the
Personal Investment Class. Each institution will render administrative support
services to its customers who are the beneficial owners of the shares of the
Personal Investment Class. Such services include, among other things,
establishment and maintenance of shareholder accounts and records; assistance in
processing purchase and redemption transactions in shares of the Personal
Investment Class; providing periodic statements showing a client's account
balance in shares of the Personal Investment Class; distribution of fund proxy
statements, annual reports and other communications to shareholders whose
accounts are serviced by the institution; and such other services as the fund
may reasonably request. Institutions will be required to certify to the fund
that they comply with applicable state law regarding registration as
broker-dealers, or that they are exempt from such registration.

  The Personal Investment Class is designed to be a convenient and economical
way to invest in an open-end diversified money market fund. It is anticipated
that most investors will perform their own subaccounting.

  Investors in the Personal Investment Class have the opportunity to receive a
somewhat higher yield than might be obtainable through direct investment in
money market instruments, and enjoy the benefits of diversification, economies
of scale and same-day liquidity. Generally, higher interest rates can be
obtained on the purchase of very large blocks of money market instruments. Of
course, any such relative increase in interest rates may be offset to some
extent by the operating expenses of the Personal Investment Class.

DIVIDENDS AND DISTRIBUTIONS

The fund expects that its distributions will consist primarily of ordinary
income.

DIVIDENDS

The fund generally declares dividends on each business day and pays dividends
monthly. A business day is any day on which both the Federal Reserve Bank of New
York and The Bank of New York, the fund's custodian, are open for business.

  Dividends are paid on settled shares of the fund as of 5:00 p.m. Eastern time.
Generally, shareholders whose purchase orders have been received by the fund
prior to 5:00 p.m. Eastern time and shareholders whose redemption proceeds have
not been wired to them on any business day are eligible to receive dividends on
that business day. The dividend declared on any day preceding a non-business day
of the fund will include the income accrued on such non-business day. Dividends
and distributions are paid in cash unless the shareholder has elected to have
such dividends and distributions reinvested in the form of additional full and
fractional shares at net asset value.

CAPITAL GAINS DISTRIBUTIONS

The fund generally distributes net realized capital gains (including net
short-term capital gains), if any, annually. The fund does not expect to realize
any long-term capital gains and losses.

                                        4
<PAGE>   73
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand the financial
performance of the Personal Investment Class. Certain information reflects
financial results for a single fund share.

  The total returns in the table represent the rate that 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 KPMG LLP, whose report, along with the
fund's financial statements, is included in the fund's annual report, which is
available upon request.

<TABLE>
<CAPTION>
                                                                 PERSONAL INVESTMENT CLASS
                                                    ----------------------------------------------------
                                                                    YEAR ENDED AUGUST 31,
                                                     1999         1998       1997       1996       1995
- --------------------------------------------------------------------------------------------------------
<S>                                               <C>        <C>        <C>        <C>        <C>
Net asset value, beginning of period              $   1.00     $   1.00   $   1.00   $   1.00   $   1.00
Income from investment operations:
  Net investment income                               0.04         0.05       0.05       0.05       0.05
Less distributions:
  Dividends from net investment income               (0.04)       (0.05)     (0.05)     (0.05)     (0.05)
Net asset value, end of period                    $   1.00     $   1.00   $   1.00   $   1.00   $   1.00
Total return                                          4.45%        5.12%      4.95%      5.04%      5.13%
- --------------------------------------------------------------------------------------------------------
Ratios/supplemental data:
- --------------------------------------------------------------------------------------------------------
Net assets, end of period (000s omitted)          $284,932     $405,801   $322,971   $192,947   $114,527
Ratio of expenses to average net assets(a)            0.59%(b)     0.58%      0.60%      0.59%      0.60%
Ratio of net investment income (loss) to average
  net assets(c)                                       4.35%(b)     5.01%      4.85%      4.91%      5.03%
- --------------------------------------------------------------------------------------------------------
</TABLE>

(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.84%, 0.83%, 0.86%, 0.92%, and 0.90% for the periods 1999-1995,
    respectively.
(b) Ratios are based on average net assets of $375,615,292.
(c) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.10%, 4.76%, 4.59%, 4.58% and 4.73% for the periods
    1999-1995, respectively.

                                        5
<PAGE>   74
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

SHAREHOLDER INFORMATION
- --------------------------------------------------------------------------------

The fund currently offers six classes of shares all of which share a common
investment objective and portfolio of investments. The six classes differ only
with respect to distribution arrangements for different categories of investors.

DISTRIBUTION AND SERVICE (12b-1) FEES

The fund has adopted a 12b-1 plan with respect to the Personal Investment Class
that allows the fund to pay distribution fees to Fund Management Company
(distributor) for the sale and distribution of its shares and fees for services
provided to shareholders. Because the fund pays these fees out of its assets on
an ongoing basis, over time these fees will increase the cost of your investment
and may cost you more than paying other types of sales charges.

PURCHASING SHARES

The minimum initial investment in the Personal Investment Class is $1,000. No
minimum amount is required for subsequent investments in the fund, nor are
minimum balances required.

  Purchase orders will be accepted for execution on the day the order is placed,
provided that the order is properly submitted and received by the transfer agent
prior to 5:00 p.m. Eastern time on a business day of the fund. Purchase orders
received after such time will be processed at the next day's net asset value.
You may purchase shares by submitting an Account Application to the fund's
transfer agent, A I M Fund Services, Inc. (transfer agent) at P.O. Box 4497,
Houston, Texas 77210-4497 prior to your initial purchase of shares. You must
open a fund account through an institution in accordance with procedures
established by such institution. A purchase order is considered received at the
time The Bank of New York receives federal funds (member bank deposits with a
Federal Reserve Bank) for the order, provided the transfer agent has received
notice of the order. Subsequent purchases of shares of the funds may also be
made via AIM LINK--Registered Trademark-- Remote, a personal computer
application software product.

  If you propose to open a fund account with an institution, you should consult
with a representative of such institution to obtain a description of the rules
governing such an account. A statement with regard to your investment in the
Personal Investment Class is supplied periodically, and confirmations of all
transactions for your account are provided by the institution promptly upon
request. In addition, proxies, periodic reports and other information from the
institution with regard to your shares of the Personal Investment Class will be
sent to you.

  You may place an order for the purchase of shares of the Personal Investment
Class with the institution. The institution is responsible for the prompt
transmission of the order to the transfer agent. The fund is normally required
to make immediate settlement in federal funds for portfolio securities
purchased. Accordingly, payment for shares of the Personal Investment Class
purchased by institutions on behalf of their clients must be in federal funds.
If an order is paid for other than in federal funds, the order may be delayed up
to two business days while the institution completes the conversion into federal
funds.

REDEEMING SHARES

You may redeem any or all of your shares at the net asset value next determined
after receipt of a redemption request in proper form by the fund. There is no
charge for redemption. Redemption requests with respect to shares of the
Personal Investment Class are normally made through your institution.

  You may request a redemption by calling the transfer agent at (800) 877-4744,
or by using AIM LINK--Registered Trademark-- Remote. Payment for redeemed shares
is normally made by Federal Reserve wire to the commercial bank account
designated in your Account Application. You may also request that payment be
made by check. We use reasonable procedures to confirm that instructions
communicated by telephone are genuine and are not liable for telephone
instructions that are reasonably believed to be genuine. Such reasonable
procedures may include recordings of telephone transactions maintained for a
reasonable period of time.

  Payment for redemption orders received prior to 5:00 p.m. Eastern time will
normally be made on the same day. Payment for shares redeemed by mail and
payment for telephone redemptions in amounts of less than $1,000 may be made by
check mailed within seven days after receipt of the redemption request in proper
form. The fund may make payment for telephone redemptions in excess of $1,000 by
check when it is considered to be in the fund's best interest to do so.

  Dividends payable up to the date of redemption on redeemed shares will
normally be paid by wire transfer on the next dividend payment date. However, if
all of the shares in your account are redeemed, you will receive dividends
payable up to the date of redemption with the proceeds of the redemption.

REDEMPTIONS BY THE FUND

If your account has been open at least one year, you have not made an additional
purchase in the account during the past six calendar months, and the value of
your account falls below $500 for three consecutive months due to redemptions or
exchanges (excluding retirement accounts), the fund has the right to redeem the
account after giving you 60 days' prior written notice. You may avoid having
your account redeemed during the notice period by bringing the account value up
to $500.

  If the fund determines that you have not provided a correct Social Security or
other tax ID number on your account application, the fund may, at its
discretion, redeem the account and distribute the proceeds to you.

                                       A-1
<PAGE>   75
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------

SHAREHOLDER INFORMATION (continued)
- --------------------------------------------------------------------------------

  THE FUND AND ITS AGENTS RESERVE THE RIGHT AT ANY TIME TO:

  - REJECT OR CANCEL ANY PART OF ANY PURCHASE ORDER;

  - MODIFY ANY TERMS OR CONDITIONS OF PURCHASE OF SHARES OF THE FUND; OR

  - WITHDRAW ALL OR ANY PART OF THE OFFERING MADE BY THIS PROSPECTUS.

PRICING OF SHARES

DETERMINATION OF NET ASSET VALUE

The price of each of the fund's shares is the fund's net asset value per share.
The fund determines the net asset value of its shares as of 5:00 p.m. Eastern
time on each day on which both the Federal Reserve Bank of New York and The Bank
of New York are open for business (business day). The fund values portfolio
securities on the basis of amortized cost, which approximates market value.

TIMING OF ORDERS

The fund prices purchase and redemption orders at the net asset value calculated
after the transfer agent receives an order in good form. If the transfer agent
receives a redemption request on a business day prior to 5:00 p.m. Eastern time,
the fund will normally wire redemption proceeds on that day. If the transfer
agent receives a redemption request after 5:00 p.m. Eastern time on a business
day of the fund, the redemption will be processed at the net asset value next
determined and the fund will normally wire proceeds on the next business day.
Shareholders will accrue dividends until the day the fund wires redemption
proceeds. The Fund may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading. The fund
reserves the right to change the time for which purchase and redemption orders
must be submitted to and received by the transfer agent for execution on the
same day on any day when the primary government securities dealers are either
closed for business or close early, or trading in money market securities is
limited due to national holidays.

TAXES

Dividends and distributions received by shareholders are taxable as ordinary
income or long-term capital gains for federal income tax purposes, whether
reinvested in additional shares or taken in cash. Distributions are taxable at
different rates depending on the length of time the fund holds its assets. Every
year, information will be sent showing the amount of dividends and distributions
received from the fund during the prior year.

  Any long-term or short-term capital gains realized from redemptions of the
fund shares will be subject to federal income tax.

  The foreign, state and local tax consequences of investing in the fund may
differ materially from the federal income tax consequences described above.
Shareholders should consult their tax advisor before investing.

                                       A-2
<PAGE>   76
                       ----------------------------------
                               TREASURY PORTFOLIO
                       ----------------------------------


OBTAINING ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------

More information may be obtained free of charge upon request. The Statement of
Additional Information (SAI), a current version of which is on file with the
Securities and Exchange Commission (SEC), contains more details about the fund
and is incorporated by reference into the prospectus (is legally a part of this
prospectus). Annual and semiannual reports to shareholders contain additional
information about the fund's investments. The fund's annual report also
discusses the market conditions and investment strategies that significantly
affected the fund's performance during its last fiscal year.

  If you have questions about this fund, another fund in The AIM Family of
Funds--Registered Trademark-- or your account, or wish to obtain free copies of
the fund's current SAI or annual or semiannual reports, please contact us

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

<TABLE>
<S>                          <C>
BY MAIL:                     A I M Fund Services, Inc.
                             P.O. Box 4497
                             Houston, TX 77210-4497

BY TELEPHONE:                (800) 877-4744

BY E-MAIL:                   [email protected]

ON THE INTERNET:             http://www.aimfunds.com
                             (prospectuses and annual
                             and semiannual reports
                             only)
</TABLE>
- ---------------------------------------------------------

You also can review and obtain copies of the fund's SAI, reports and other
information at the SEC's Public Reference Room in Washington, DC; on the EDGAR
database on the SEC's Internet website (http://www.sec.gov); or, after paying a
duplication fee, by sending a letter to the SEC's Public Reference Section,
Washington, DC 20549-0102 or by sending an electronic mail request to
[email protected]. Please call the SEC at 1-202-942-8090 for information about
the Public Reference Room.

- -----------------------------------
 Treasury Portfolio
 SEC 1940 Act file number: 811-2729
- -----------------------------------

[AIM LOGO APPEARS HERE]      www.aimfunds.com             INVEST WITH DISCIPLINE
                                                        --Registered Trademark--
<PAGE>   77
        TREASURY PORTFOLIO

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

        PRIVATE INVESTMENT CLASS
        Treasury Portfolio seeks to maximize current income consistent with the
        preservation of capital and the maintenance of liquidity.

        PROSPECTUS
        DECEMBER 17, 1999

                                       This prospectus contains important
                                       information about the Private
                                       Investment Class of the fund. Please
                                       read it before investing and keep it
                                       for future reference.

                                       As with all other mutual fund
                                       securities, the Securities and
                                       Exchange Commission has not approved
                                       or disapproved these securities or
                                       determined whether the information
                                       in this prospectus is adequate or
                                       accurate. Anyone who tells you
                                       otherwise is committing a crime.

                                       There can be no assurance that the
                                       fund will be able to maintain a
                                       stable net asset value of $1.00 per
                                       share.

        [AIM LOGO APPEARS HERE]                  INVEST WITH DISCIPLINE

                                                --Registered Trademark--
<PAGE>   78
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

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

<TABLE>
<S>                                       <C>

INVESTMENT OBJECTIVE AND STRATEGIES           1

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

PRINCIPAL RISKS OF INVESTING IN THE
  FUND                                        1

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

PERFORMANCE INFORMATION                       2

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

Annual Total Returns                          2

Performance Table                             2

FEE TABLE AND EXPENSE EXAMPLE                 3

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

Fee Table                                     3

Expense Example                               3

FUND MANAGEMENT                               4

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

The Advisor                                   4

Advisor Compensation                          4

OTHER INFORMATION                             4

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

Suitability for Investors                     4

Dividends and Distributions                   4

FINANCIAL HIGHLIGHTS                          5

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

SHAREHOLDER INFORMATION                     A-1

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

Distribution and Service (12b-1) Fees       A-1

Purchasing Shares                           A-1

Redeeming Shares                            A-1

Pricing of Shares                           A-2

Taxes                                       A-2

OBTAINING ADDITIONAL INFORMATION     Back Cover

- - - - - - - - - - - - - - - - - - - - - - - - - -
</TABLE>

The AIM Family of Funds, The AIM Family of Funds and Design (i.e., the AIM
logo), AIM and Design, AIM, AIM LINK, AIM Institutional Funds, aimfunds.com, La
Familia AIM de Fondos, La Familia AIM de Fondos and Design and Invest with
Discipline are registered service marks and AIM Bank Connection, AIM Funds, AIM
Funds and Design, AIM Internet Connect and AIM Investor are service marks of
A I M Management Group Inc.

No dealer, salesperson or any other person has been authorized to give any
information or to make any representations other than those contained in this
prospectus, and you should not rely on such other information or
representations.
<PAGE>   79
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

INVESTMENT OBJECTIVE AND STRATEGIES
- --------------------------------------------------------------------------------

The fund's investment objective is to maximize current income consistent with
the preservation of capital and the maintenance of liquidity.

  The fund attempts to meet this objective by investing in direct obligations of
the U.S. Treasury, including bills, notes and bonds, and repurchase agreements
secured by those obligations. The fund will maintain a weighted average maturity
of 90 days or less. The fund invests in compliance with Rule 2a-7 under the
Investment Company Act of 1940.

  The portfolio managers focus on securities they believe have favorable
prospects for current income consistent with the preservation of capital and the
maintenance of liquidity. The portfolio managers usually hold portfolio
securities to maturity, but may sell a particular security when they deem it
advisable, such as when any of the factors above materially changes.

  In anticipation of or in response to adverse market conditions, for cash
management purposes, or for defensive purposes, the fund may temporarily hold
all or a portion of its assets in cash or shares of affiliated money market
funds. As a result, the fund may not achieve its investment objective.

PRINCIPAL RISKS OF INVESTING IN THE FUND
- --------------------------------------------------------------------------------

An investment in the fund is not a deposit of a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. Although the fund seeks to preserve the value of your investment at
$1.00 per share, it is possible to lose money by investing in the fund.
Additionally, the fund's yield will vary as the short-term securities in its
portfolio mature and the proceeds are reinvested in securities with different
interest rates.

  The following factors could reduce the fund's income and/or share price:

- - sharply rising interest rates; and

- - downgrades of credit ratings or defaults of any of the fund's holdings.

  If the seller of a repurchase agreement in which the fund invests defaults on
its obligation or declares bankruptcy, the fund may experience delays in selling
the securities underlying the repurchase agreement. As a result, the fund may
incur losses arising from decline in the value of those securities, reduced
levels of income and expenses of enforcing its rights.

  The value of your shares could be adversely affected if the computer systems
used by the fund's investment advisor and the fund's other service providers are
unable to distinguish the year 2000 from the year 1900.

  The fund's investment advisor and independent technology consultants are
working to avoid year 2000-related problems in its systems and to obtain
assurances that other service providers are taking similar steps. Year 2000
problems may also affect issuers in whose securities the fund invests.

                                        1
<PAGE>   80
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
The bar chart and table shown below provide an indication of the risks of
investing in the fund. The fund's past performance is not necessarily an
indication of its future performance.

ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
The following bar chart shows changes in the performance of the Private
Investment Class shares from year to year. Private Investment Class shares are
not subject to sales loads.

                                    [GRAPH]

<TABLE>
<CAPTION>
Year Ended December 31                    Return (%)
- ----------------------                    ----------
<S>                                       <C>
1992....................................    3.53%
1993....................................    2.85%
1994....................................    3.84%
1995....................................    5.63%
1996....................................    5.09%
1997....................................    5.25%
1998....................................    5.16%
</TABLE>

The Private Investment Class shares' year-to-date total return as of September
30, 1999 was 3.41%.

  During the periods shown in the bar chart, the highest quarterly return was
1.42% (quarter ended June 30, 1995) and the lowest quarterly return was 0.70%
(quarter ended June 30, 1993).

PERFORMANCE TABLE

The following performance table reflects the performance of Private Investment
Class shares over the periods indicated.

<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS
- ------------------------------------------------------------------------------------------------------
(for the periods ended                                                          SINCE      INCEPTION
December 31, 1998)                               1 YEAR   5 YEARS   10 YEARS   INCEPTION     DATE
- ------------------------------------------------------------------------------------------------------
<S>                                              <C>      <C>       <C>        <C>         <C>
Private Investment Class                          5.16%    4.99%        --       4.48%      11/22/91
- ------------------------------------------------------------------------------------------------------
</TABLE>

Private Investment Class shares' seven-day yield on December 31, 1998 was 4.51%.
For the current seven-day yield, call (800) 877-7748.

                                        2
<PAGE>   81
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FEE TABLE AND EXPENSE EXAMPLE
- --------------------------------------------------------------------------------

FEE TABLE

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

<TABLE>
<CAPTION>
SHAREHOLDER FEES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(fees paid directly from           PRIVATE
your investment)               INVESTMENT CLASS
- -----------------------------------------------
<S>                            <C>
Maximum Sales Charge (Load)
Imposed on Purchases
(as a percentage of
offering price)                      None
Maximum Deferred
Sales Charge (Load)
(as a percentage of
original purchase
price or redemption
proceeds, whichever is less)         None
- -----------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(expenses that are deducted        PRIVATE
from fund assets)              INVESTMENT CLASS
- -----------------------------------------------
<S>                            <C>
Management Fees                      0.06%
Distribution and/or
Service (12b-1) Fees                 0.50
Other Expenses                       0.03
Total Annual Fund
Operating Expenses                   0.59
Fee Waver(1)                         0.20
Net Expenses                         0.39
- -----------------------------------------------
</TABLE>

(1) The distributor has contractually agreed to waive 0.20% of the Rule 12b-1
    distribution plan fee.
You should also consider the effect of any account fees charged by the financial
institution managing the account.
  As a result of 12b-1 fees, long-term shareholders in the fund may pay more
than the maximum permitted initial sales charge.

EXPENSE EXAMPLE

This example is intended to help you compare the costs of investing in the
Private Investment Class of 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 gross operating expenses remain the same. To the extent fees are waived
or expenses are reimbursed, the expenses will be lower. Although your actual
returns and costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
                 1 YEAR   3 YEARS   5 YEARS   10 YEARS
- ------------------------------------------------------
<S>              <C>      <C>       <C>       <C>
Private
Investment
Class             $60      $189      $329       $738
- ------------------------------------------------------
</TABLE>

                                        3
<PAGE>   82
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FUND MANAGEMENT
- --------------------------------------------------------------------------------

THE ADVISOR

A I M Advisors, Inc. (the advisor) serves as the fund's investment advisor and
is responsible for its day-to-day management. The advisor is located at 11
Greenway Plaza, Suite 100, Houston, Texas 77046-1173. The advisor supervises all
aspects of the fund's operations and provides investment advisory services to
the fund, including obtaining and evaluating economic, statistical and financial
information to formulate and implement investment programs for the fund.

  The advisor has acted as an investment advisor since its organization in 1976.
Today, the advisor, together with its subsidiaries, advises or manages over 125
investment portfolios, including the fund, encompassing a broad range of
investment objectives.

ADVISOR COMPENSATION

During the fiscal year ended August 31, 1999, the advisor received compensation
of 0.06% of average daily net assets.

OTHER INFORMATION
- --------------------------------------------------------------------------------

SUITABILITY FOR INVESTORS

The Private Investment Class of the fund is intended for use primarily by
customers of banks, certain broker-dealers and other institutions
(institutions). Individuals, corporations, partnerships and other businesses
that maintain qualified accounts at an institution may invest in shares of the
Private Investment Class. Each institution will render administrative support
services to its customers who are the beneficial owners of the shares of the
Private Investment Class. Such services include, among other things,
establishment and maintenance of shareholder accounts and records; assistance in
processing purchase and redemption transactions in shares of the Private
Investment Class; providing periodic statements showing a client's account
balance in shares of the Private Investment Class; distribution of fund proxy
statements, annual reports and other communications to shareholders whose
accounts are serviced by the institution; and such other services as the fund
may reasonably request. Institutions will be required to certify to the fund
that they comply with applicable state law regarding registration as
broker-dealers, or that they are exempt from such registration.

  The Private Investment Class is designed to be a convenient and economical way
to invest in an open-end diversified money market fund. It is anticipated that
most investors will perform their own subaccounting.

  Investors in the Private Investment Class have the opportunity to receive a
somewhat higher yield than might be obtainable through direct investment in
money market instruments, and enjoy the benefits of diversification, economies
of scale and same-day liquidity. Generally, higher interest rates can be
obtained on the purchase of very large blocks of money market instruments. Of
course, any such relative increase in interest rates may be offset to some
extent by the operating expenses of the Private Investment Class.

DIVIDENDS AND DISTRIBUTIONS

The fund expects that its distributions will consist primarily of ordinary
income.

DIVIDENDS

The fund generally declares dividends on each business day and pays dividends
monthly. A business day is any day on which both the Federal Reserve Bank of New
York and The Bank of New York, the fund's custodian, are open for business.

  Dividends are paid to settled shares of the fund as of 5:00 p.m. Eastern time.
Generally, shareholders whose purchase orders have been received by the fund
prior to 5:00 p.m. Eastern time and shareholders whose redemption proceeds have
not been wired to them on any business day are eligible to receive dividends on
that business day. The dividend declared on any day preceding a non-business day
of the fund will include the income accrued on such non-business day. Dividends
and distributions are paid in cash unless the shareholder has elected to have
such dividends and distributions reinvested in the form of additional full and
fractional shares at the net asset value.

CAPITAL GAINS DISTRIBUTIONS

The fund generally distributes net realized capital gains (including net
short-term capital gains), if any, annually. The fund does not expect to realize
any long-term capital gains and losses.

                                        4
<PAGE>   83
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand the financial
performance of the Private Investment Class. Certain information reflects
financial results for a single fund share.

  The total returns in the table represent the rate that 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 KPMG LLP, whose report, along with the
fund's financial statements, is included in the fund's annual report, which is
available upon request.

<TABLE>
<CAPTION>
                                                                PRIVATE INVESTMENT CLASS
                                                  ----------------------------------------------------
                                                                 YEAR ENDED AUGUST 31,
                                                    1999       1998       1997       1996       1995
- ------------------------------------------------------------------------------------------------------
<S>                                               <C>        <C>        <C>        <C>        <C>
Net asset value, beginning of period              $    1.00  $    1.00  $    1.00  $    1.00  $      1.00
Income from investment operations:
  Net investment income                                0.05       0.05       0.05       0.05         0.05
Less distributions:
  Dividends from net investment income                (0.05)     (0.05)     (0.05)     (0.05)       (0.05)
Net asset value, end of period                    $    1.00  $    1.00  $    1.00  $    1.00  $      1.00
Total return                                           4.66%      5.33%      5.16%      5.25%        5.34%
- ------------------------------------------------------------------------------------------------------
Ratios/supplemental data:
- ------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<S>                                               <C>        <C>        <C>        <C>        <C>
Net assets, end of period (000s omitted)          $415,184   $360,307   $463,441   $352,537   $394,585
Ratio of expenses to average net assets(a)            0.39%(b)     0.38%     0.39%     0.39%      0.40%
Ratio of net investment income to average net
  assets(c)                                           4.55%(b)     5.20%     5.05%     5.14%      5.23%
- ------------------------------------------------------------------------------------------------------
</TABLE>

(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.59%, 0.58%, 0.59%, 0.59% and 0.60% for the periods 1999-1995,
    respectively.
(b) Ratios based on average net assets of $354,442,723.
(c) After few waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.35%, 5.00%, 4.85%, 4.94% and 5.03% for the periods
    1999-1995, respectively.

                                        5
<PAGE>   84
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------
SHAREHOLDER INFORMATION
- --------------------------------------------------------------------------------


The fund currently offers six classes of shares all of which share a common
investment objective and portfolio of investments. The six classes differ only
with respect to distribution arrangements for different categories of investors.

DISTRIBUTION AND SERVICE (12b-1) FEES

The fund has adopted a 12b-1 plan with respect to the Private Investment Class
that allows the fund to pay distribution fees to Fund Management Company
(distributor) for the sale and distribution of its shares and fees for services
provided to shareholders. Because the fund pays these fees out of its assets on
an ongoing basis, over time these fees will increase the cost of your investment
and may cost you more than paying other types of sales charges.

PURCHASING SHARES

The minimum initial investment in the Private Investment Class is $10,000. No
minimum amount is required for subsequent investments in the fund, nor are
minimum balances required.

  Purchase orders will be accepted for execution on the day the order is placed,
provided that the order is properly submitted and received by the transfer agent
prior to 5:00 p.m. Eastern time on a business day of the fund. Purchase orders
received after such time will be processed at the next day's net asset value.
You may purchase shares by submitting an Account Application to the fund's
transfer agent, A I M Fund Services, Inc. (transfer agent) at P.O. Box 4497,
Houston, Texas 77210-4497 prior to your initial purchase of shares. You must
open a fund account through an institution in accordance with procedures
established by such institution. A purchase order is considered received at the
time The Bank of New York receives federal funds (member bank deposits with a
Federal Reserve Bank) for the order, provided the transfer agent has received
notice of the order. Subsequent purchases of shares of the funds may also be
made via AIM LINK--Registered Trademark-- Remote, a personal computer
application software product.

  If you propose to open a fund account with an institution, you should consult
with a representative of such institution to obtain a description of the rules
governing such an account. A statement with regard to your investment in the
Private Investment Class is supplied periodically, and confirmations of all
transactions for your account are provided by the institution promptly upon
request. In addition, proxies, periodic reports and other information from the
institution with regard to your shares of the Private Investment Class will be
sent to you.

  You may place an order for the purchase of shares of the Private Investment
Class with the institution. The institution is responsible for the prompt
transmission of the order to the transfer agent. The fund is normally required
to make immediate settlement in federal funds for portfolio securities
purchased. Accordingly, payment for shares of the Private Investment Class
purchased by institutions on behalf of their clients must be in federal funds.
If an order to purchase shares is paid for other than in federal funds, the
order may be delayed up to two business days while the institution completes the
conversion into federal funds.

REDEEMING SHARES

You may redeem any or all of your shares at the net asset value next determined
after receipt of a redemption request in proper form by the fund. There is no
charge for redemption. Redemption requests with respect to shares of the Private
Investment Class are normally made through your institution.

  You may request a redemption by calling the transfer agent at (800) 877-7748,
or by using AIM LINK--Registered Trademark-- Remote. Payment for redeemed shares
is normally made by Federal Reserve wire to the commercial bank account
designated in your Account Application. You may also request that payment be
made by check. We use reasonable procedures to confirm that instructions
communicated by telephone are genuine and are not liable for telephone
instructions that are reasonably believed to be genuine. Such reasonable
procedures may include recordings of telephone transactions maintained for a
reasonable period of time.

  Payment for redemption orders received prior to 5:00 p.m. Eastern time will
normally be made on the same day. Payment for shares redeemed by mail and
payment for telephone redemptions in amounts of less than $1,000 may be made by
check mailed within seven days after receipt of the redemption request in proper
form. The fund may make payment for telephone redemptions in excess of $1,000 by
check when it is considered to be in the fund's best interest to do so.

  Dividends payable up to the date of redemption on redeemed shares will
normally be paid by wire transfer on the next dividend payment date. However, if
all of the shares in your account are redeemed, you will receive dividends
payable up to the date of redemption with the proceeds of the redemption.

REDEMPTIONS BY THE FUND

If your account has been open at least one year, you have not made an additional
purchase in the account during the past six calendar months, and the value of
your account falls below $500 for three consecutive months due to redemptions or
exchanges (excluding retirement accounts), the fund has the right to redeem the
account after giving you 60 days' prior written notice. You may avoid having
your account redeemed during the notice period by bringing the account value up
to $500.

  If the fund determines that you have not provided a correct Social Security or
other tax ID number on your account application, the fund may, at its
discretion, redeem the account and distribute the proceeds to you.

                                       A-1
<PAGE>   85
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION (continued)
- --------------------------------------------------------------------------------

  THE FUND AND ITS AGENTS RESERVES THE RIGHT AT ANY TIME TO:

  - REJECT OR CANCEL ANY PART OF ANY PURCHASE ORDER;

  - MODIFY ANY TERMS OR CONDITIONS OF PURCHASE OF SHARES OF THE FUND; OR

  - WITHDRAW ALL OR ANY PART OF THE OFFERING MADE BY THIS PROSPECTUS.

PRICING OF SHARES

DETERMINATION OF NET ASSET VALUE

The price of each of the fund's shares is the fund's net asset value per share.
The fund determines the net asset value of its shares as of 5:00 p.m. Eastern
time on each day on which both the Federal Reserve Bank of New York and The Bank
of New York are open for business (business day). The fund values portfolio
securities on the basis of amortized cost, which approximates market value.

TIMING OF ORDERS

The fund prices purchase and redemption orders at the net asset value calculated
after the transfer agent receives an order in good form. If the transfer agent
receives a redemption request on a business day prior to 5:00 p.m. Eastern time,
the fund will normally wire redemption proceeds on that day. If the transfer
agent receives a redemption request after 5:00 p.m. Eastern time on a business
day of the fund, the redemption will be processed at the net asset value next
determined and the fund will normally wire proceeds on the next business day.
Shareholders will accrue dividends until the day the fund wires redemption
proceeds. The Fund may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading. The fund
reserves the right to change the time for which purchase and redemption orders
must be submitted to and received by the transfer agent for execution on the
same day on any day when the primary government securities dealers are either
closed for business or close early, or trading in money market securities is
limited due to national holidays.

TAXES

Dividends and distributions received by shareholders are taxable as ordinary
income or long-term capital gains for federal income tax purposes, whether
reinvested in additional shares or taken in cash. Distributions are taxable at
different rates depending on the length of time the fund holds its assets. Every
year, information will be sent showing the amount of dividends and distributions
received from the fund during the prior year.

  Any long-term or short-term capital gains realized from redemptions of the
fund shares will be subject to federal income tax.

  The foreign, state and local tax consequences of investing in the fund may
differ materially from the federal income tax consequences described above.
Shareholders should consult their tax advisor before investing.

                                       A-2
<PAGE>   86
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

OBTAINING ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------

More information may be obtained free of charge upon request. The Statement of
Additional Information (SAI), a current version of which is on file with the
Securities and Exchange Commission (SEC), contains more details about the fund
and is incorporated by reference into the prospectus (is legally a part of this
prospectus). Annual and semiannual reports to shareholders contain additional
information about the fund's investments. The fund's annual report also
discusses the market conditions and investment strategies that significantly
affected the fund's performance during its last fiscal year.

  If you have questions about this fund, another fund in The AIM Family of
Funds--Registered Trademark-- or your account, or wish to obtain free copies
of the fund's current SAI or annual or semiannual reports, please contact us

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

<TABLE>
<S>                          <C>
BY MAIL:                     A I M Fund Services, Inc.
                             P.O. Box 4497
                             Houston, TX 77210-4497

BY TELEPHONE:                (800) 877-7748

BY E-MAIL:                   [email protected]

ON THE INTERNET:             http://www.aimfunds.com
                             (prospectuses and annual
                             and semiannual reports
                             only)
</TABLE>

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

You also can review and obtain copies of the fund's SAI, reports and other
information at the SEC's Public Reference Room in Washington, DC; on the EDGAR
database on the SEC's Internet website (http://www.sec.gov); or, after paying a
duplication fee, by sending a letter to the SEC's Public Reference Section,
Washington, DC 20549-0102 or by sending an electronic mail request to
[email protected]. Please call the SEC at 1-202-942-8090 for information about
the Public Reference Room.

- -----------------------------------
 Treasury Portfolio
 SEC 1940 Act file number: 811-2729
- -----------------------------------

[AIM LOGO APPEARS HERE]      www.aimfunds.com             INVEST WITH DISCIPLINE
                                                        --Registered Trademark--
<PAGE>   87
        TREASURY PORTFOLIO

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

        RESERVE CLASS
        Treasury Portfolio seeks to maximize current income consistent with the
        preservation of capital and the maintenance of liquidity.

        PROSPECTUS
        DECEMBER 17, 1999

                                       This prospectus contains important
                                       information about the Reserve Class
                                       of the fund. Please read it before
                                       investing and keep it for future
                                       reference.

                                       As with all other mutual fund
                                       securities, the Securities and
                                       Exchange Commission has not approved
                                       or disapproved these securities or
                                       determined whether the information
                                       in this prospectus is adequate or
                                       accurate. Anyone who tells you
                                       otherwise is committing a crime.

                                       There can be no assurance that the
                                       fund will be able to maintain a
                                       stable net asset value of $1.00 per
                                       share.

        [AIM LOGO APPEARS HERE]                  INVEST WITH DISCIPLINE
                                                --Registered Trademark--
<PAGE>   88
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

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

<TABLE>
<S>                                       <C>

INVESTMENT OBJECTIVE AND STRATEGIES           1

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

PRINCIPAL RISKS OF INVESTING IN THE
  FUND                                        1

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

PERFORMANCE INFORMATION                       2

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

Annual Total Returns                          2

Performance Table                             2

FEE TABLE AND EXPENSE EXAMPLE                 3

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

Fee Table                                     3

Expense Example                               3

FUND MANAGEMENT                               4

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

The Advisor                                   4

Advisor Compensation                          4

OTHER INFORMATION                             4

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

Suitability for Investors                     4

Dividends and Distributions                   4

FINANCIAL HIGHLIGHTS                          5

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

SHAREHOLDER INFORMATION                     A-1

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

Distribution and Service (12b-1) Fees       A-1

Purchasing Shares                           A-1

Redeeming Shares                            A-1

Pricing of Shares                           A-2

Taxes                                       A-2

OBTAINING ADDITIONAL INFORMATION     Back Cover

- - - - - - - - - - - - - - - - - - - - - - - - - -
</TABLE>

The AIM Family of Funds, The AIM Family of Funds and Design (i.e., the AIM
logo), AIM and Design, AIM, AIM LINK, AIM Institutional Funds, aimfunds.com, La
Familia AIM de Fondos, La Familia AIM de Fondos and Design and Invest with
Discipline are registered service marks and AIM Bank Connection, AIM Funds, AIM
Funds and Design, AIM Internet Connect and AIM Investor are service marks of
A I M Management Group Inc.

No dealer, salesperson or any other person has been authorized to give any
information or to make any representations other than those contained in this
prospectus, and you should not rely on such other information or
representations.
<PAGE>   89
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

INVESTMENT OBJECTIVE AND STRATEGIES
- --------------------------------------------------------------------------------

The fund's investment objective is to maximize current income consistent with
the preservation of capital and the maintenance of liquidity.

  The fund attempts to meet this objective by investing in direct obligations of
the U.S. Treasury, including bills, notes and bonds, and repurchase agreements
secured by those obligations. The fund will maintain a weighted average maturity
of 90 days or less. The fund invests in compliance with Rule 2a-7 under the
Investment Company Act of 1940.

  The portfolio managers focus on securities they believe have favorable
prospects for current income consistent with the preservation of capital and the
maintenance of liquidity. The portfolio managers usually hold portfolio
securities to maturity, but may sell a particular security when they deem it
advisable, such as when any of the factors above materially changes.

  In anticipation of or in response to adverse market conditions, for cash
management purposes, or for defensive purposes, the fund may temporarily hold
all or a portion of its assets in cash or shares of affiliated money market
funds. As a result, the fund may not achieve its investment objective.

PRINCIPAL RISKS OF INVESTING IN THE FUND
- --------------------------------------------------------------------------------

An investment in the fund is not a deposit of a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. Although the fund seeks to preserve the value of your investment at
$1.00 per share, it is possible to lose money by investing in the fund.
Additionally, the fund's yield will vary as the short-term securities in its
portfolio mature and the proceeds are reinvested in securities with different
interest rates.

  The following factors could reduce the fund's income and/or share price:

- - sharply rising interest rates; and

- - downgrades of credit ratings or defaults of any of the fund's holdings.

  If the seller of a repurchase agreement in which the fund invests defaults on
its obligation or declares bankruptcy, the fund may experience delays in selling
the securities underlying the repurchase agreement. As a result, the fund may
incur losses arising from decline in the value of those securities, reduced
levels of income and expenses of enforcing its rights.

  The value of your shares could be adversely affected if the computer systems
used by the fund's investment advisor and the fund's other service provides are
unable to distinguish the year 2000 from the year 1900.

  The fund's investment advisor and independent technology consultants are
working to avoid year 2000-related problems in its systems and to obtain
assurances that other service providers are taking similar steps. Year 2000
problems may also affect issuers in whose securities the fund invests.

                                        1
<PAGE>   90
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
The bar chart and table shown below provide an indication of the risks of
investing in the fund. The fund's past performance is not necessarily an
indication of its future performance.

ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
The following bar chart shows changes in the performance of the Institutional
Class shares from year to year. Neither the Reserve Class shares nor the
Institutional Class shares are subject to sales loads.

                                    [GRAPH]

<TABLE>
<CAPTION>
                                          Annual
Year Ended                                Total
December 31                               Return
- -----------                               ------
<S>                                       <C>
1989....................................  9.21%
1990....................................  8.27%
1991....................................  6.16%
1992....................................  3.86%
1993....................................  3.15%
1994....................................  4.15%
1995....................................  5.95%
1996....................................  5.41%
1997....................................  5.56%
1998....................................  5.48%
</TABLE>

The returns are those of the fund's Institutional Class shares, which are not
offered in this prospectus. Reserve Class shares would have substantially
similar annual returns because the shares are invested in the same portfolio of
securities but would be lower to the extent that the classes have different
expenses.

  The Institutional Class shares' year-to-date total return as of September 30,
1999 was 3.64%.

  During the periods shown in the bar chart, Institutional Class' highest
quarterly return was 2.32% (quarter ended June 30, 1989) and its lowest
quarterly return was 0.77% (quarter ended June 30, 1993).

PERFORMANCE TABLE

The following performance table reflects the performance of Institutional Class
shares over the periods indicated.

<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS
- ------------------------------------------------------------------------------------------------------
(for the periods ended                                                          SINCE      INCEPTION
December 31, 1998)                               1 YEAR   5 YEARS   10 YEARS   INCEPTION     DATE
- ------------------------------------------------------------------------------------------------------
<S>                                              <C>      <C>       <C>        <C>         <C>
Institutional Class                               5.48%    5.31%      5.71%      6.34%      04/12/84
Reserve Class                                       --       --         --         --       01/04/99
- ------------------------------------------------------------------------------------------------------
</TABLE>

For the current seven-day yield of Reserve Class shares, call (800) 417-8837.

                                        2
<PAGE>   91
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FEE TABLE AND EXPENSE EXAMPLE
- --------------------------------------------------------------------------------

FEE TABLE

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

<TABLE>
<CAPTION>
SHAREHOLDER FEES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(fees paid directly from
your investment)                 RESERVE CLASS
- ----------------------------------------------
<S>                              <C>
Maximum Sales Charge (Load)
Imposed on Purchases
(as a percentage of
offering price)                       None

Maximum Deferred
Sales Charge (Load)
(as a percentage of
original purchase
price or redemption
proceeds, whichever is less)          None
- ----------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(expenses that are deducted
from fund assets)                RESERVE CLASS
- ----------------------------------------------
<S>                              <C>
Management Fees                       0.06%
Distribution and/or
Service (12b-1) Fees                  1.00
Other Expenses                        0.03
Total Annual Fund
Operating Expenses                    1.09
Fee Waiver(1)                         0.20
Net Expenses                          0.89
- ----------------------------------------------
</TABLE>

(1) The distributor has contractually agreed to waive 0.20% of the Rule 12b-1
    distribution plan fee.
You should also consider the effect of any account fees charged by the financial
institution managing the account.
  As a result of 12b-1 fees, long-term shareholders in the fund may pay more
than the maximum permitted initial sales charge.

EXPENSE EXAMPLE

This example is intended to help you compare the costs of investing in the
Reserve Class of 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 gross operating expenses remain the same. To the extent fees are waived
or expenses are reimbursed, the expenses will be lower. Although your actual
returns and costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
                  1 YEAR   3 YEARS   5 YEARS   10 YEARS
- -------------------------------------------------------
<S>               <C>      <C>       <C>       <C>
Reserve Class      $111     $347      $601      $1,329
- -------------------------------------------------------
</TABLE>

                                        3
<PAGE>   92
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FUND MANAGEMENT
- --------------------------------------------------------------------------------

THE ADVISOR

A I M Advisors, Inc. (the advisor) serves as the fund's investment advisor and
is responsible for its day-to-day management. The advisor is located at 11
Greenway Plaza, Suite 100, Houston, Texas 77046-1173. The advisor supervises all
aspects of the fund's operations and provides investment advisory services to
the fund, including obtaining and evaluating economic, statistical and financial
information to formulate and implement investment programs for the fund.

  The advisor has acted as an investment advisor since its organization in 1976.
Today, the advisor, together with its subsidiaries, advises or manages over 125
investment portfolios, including the fund, encompassing a broad range of
investment objectives.

ADVISOR COMPENSATION

During the fiscal year ended August 31, 1999, the advisor received compensation
of 0.06% of average daily net assets.

OTHER INFORMATION
- --------------------------------------------------------------------------------

SUITABILITY FOR INVESTORS

The Reserve Class of the fund is intended for use primarily by customers of
banks, certain broker-dealers and other institutions (institutions).
Individuals, corporations, partnerships and other businesses that maintain
qualified accounts at an institution may invest in shares of the Reserve Class.
Each institution will render administrative support services to its customers
who are the beneficial owners of the shares of the Reserve Class. Such services
include, among other things, establishment and maintenance of shareholder
accounts and records; assistance in processing purchase and redemption
transactions in shares of the Reserve Class; providing periodic statements
showing a client's account balance in shares of the Reserve Class; distribution
of fund proxy statements, annual reports and other communications to
shareholders whose accounts are serviced by the institution; and such other
services as the fund may reasonably request. Institutions will be required to
certify to the fund that they comply with applicable state law regarding
registration as broker-dealers, or that they are exempt from such registration.

  The Reserve Class is designed to be a convenient and economical way to invest
in an open-end diversified money market fund. It is anticipated that most
investors will perform their own subaccounting.

  Investors in the Reserve Class have the opportunity to receive a somewhat
higher yield than might be obtainable through direct investment in money market
instruments, and enjoy the benefits of diversification, economies of scale and
same-day liquidity. Generally, higher interest rates can be obtained on the
purchase of very large blocks of money market instruments. Of course, any such
relative increase in interest rates may be offset to some extent by the
operating expenses of the Reserve Class.

DIVIDENDS AND DISTRIBUTIONS

The fund expects that its distributions will consist primarily of ordinary
income.

DIVIDENDS

The fund generally declares dividends on each business day and pays dividends
monthly. A business day is any day on which both the Federal Reserve Bank of New
York and The Bank of New York, the fund's custodian, are open for business.

  Dividends are paid on settled shares of the fund as of 5:00 p.m. Eastern time.
Generally, shareholders whose purchase orders have been received by the fund
prior to 5:00 p.m. Eastern time and shareholders whose redemption proceeds have
not been wired to them on any business day are eligible to receive dividends on
that business day. The dividend declared on any day preceding a non-business day
of the fund will include the income accrued on such non-business day. Dividends
and distributions are paid in cash unless the shareholder has elected to have
such dividends and distributions reinvested in the form of additional full and
fractional shares at the net asset value.

CAPITAL GAINS DISTRIBUTIONS

The fund generally distributes net realized capital gains (including net
short-term capital gains), if any, annually. The fund does not expect to realize
any long-term capital gains and losses.

                                        4
<PAGE>   93
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand the financial
performance of the Reserve Class. Certain information reflects financial results
for a single fund share.

  The total returns in the table represent the rate that 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 KPMG LLP, whose report, along with the
fund's financial statements, is included in the fund's annual report, which is
available upon request.

<TABLE>
<CAPTION>
                                                               RESERVE CLASS
                                                              ---------------
                                                              FOR THE PERIOD
                                                              JANUARY 4, 1999
                                                                  THROUGH
                                                                AUGUST 31,
                                                                   1999
- -----------------------------------------------------------------------------
<S>                                                           <C>
Net asset value, beginning of period                             $   1.00
Income from investment operations:
  Net investment income                                              0.03
Less distributions:
  Dividends from net investment income                              (0.03)
Net asset value, end of period                                   $   1.00
Total return(a)                                                      2.63%
- -----------------------------------------------------------------------------
Ratios/supplemental data:
- -----------------------------------------------------------------------------
Net assets, end of period (000s omitted)                         $119,976
Ratio of expenses to average net assets(b)                           0.89%(c)
Ratio of net investment income to average net assets(d)              2.09%(c)
- -----------------------------------------------------------------------------
</TABLE>

(a) Not annualized for periods less than one year.
(b) After fee waivers and/or expense reimbursements. Ratio of expenses to
    average net assets prior to fee waivers and/or expense reimbursements was
    1.09%.
(c) Ratios based on average net assets of $28,324,369.
(d) After fee waivers and/or expense reimbursements. Ratio of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursement was 1.89%.

                                        5
<PAGE>   94
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION
- --------------------------------------------------------------------------------

The fund currently offers six classes of shares all of which share a common
investment objective and portfolio of investments. The six classes differ only
with respect to distribution arrangements for different categories of investors.

DISTRIBUTION AND SERVICE (12b-1) FEES

The fund has adopted a 12b-1 plan with respect to the Reserve Class that allows
the fund to pay distribution fees to Fund Management Company (distributor) for
the sale and distribution of its shares and fees for services provided to
shareholders. Because the fund pays these fees out of its assets on an ongoing
basis, over time these fees will increase the cost of your investment and may
cost you more than paying other types of sales charges.

PURCHASING SHARES

The minimum initial investment in the Reserve Class is $1,000. No minimum amount
is required for subsequent investments in the fund, nor are minimum balances
required.

  Purchase orders will be accepted for execution on the day the order is placed,
provided that the order is properly submitted and received by the transfer agent
prior to 5:00 p.m. Eastern time on a business day of the fund. Purchase orders
received after such time will be processed at the next day's net asset value.
You may purchase shares by submitting an Account Application to the fund's
transfer agent, A I M Fund Services, Inc. (transfer agent) at P.O. Box 4497,
Houston, Texas 77210-4497 prior to your initial purchase of shares. You must
open a fund account through an institution in accordance with procedures
established by such institution. A purchase order is considered received at the
time The Bank of New York receives federal funds (member bank deposits with a
Federal Reserve Bank) for the order, provided the transfer agent has received
notice of the order. Subsequent purchases of shares of the funds may also be
made via AIM LINK--Registered Trademark-- Remote, a personal computer
application software product.

  If you propose to open a fund account with an institution, you should consult
with a representative of such institution to obtain a description of the rules
governing such an account. A statement with regard to your investment in the
Reserve Class is supplied periodically, and confirmations of all transactions
for your account are provided by the institution promptly upon request. In
addition, proxies, periodic reports and other information from the institution
with regard to shares of the Reserve Class will be sent to you.

  You may place an order for the purchase of shares of the Reserve Class with
the institution. The institution is responsible for the prompt transmission of
the order to the transfer agent. The fund is normally required to make immediate
settlement in federal funds for portfolio securities purchased. Accordingly,
payment for shares of the Reserve Class purchased by institutions on behalf of
their clients must be in federal funds. If an order to purchase shares is paid
for other than in federal funds, the order may be delayed up to two business
days while the institution completes the conversion into federal funds.

REDEEMING SHARES

You may redeem any or all of your shares at the net asset value next determined
after receipt of a redemption request in proper form by the fund. There is no
charge for redemption. Redemption requests with respect to shares of the Reserve
Class are normally made through your institution.

  You may request a redemption by calling the transfer agent at (800) 417-8837,
or by using AIM LINK--Registered Trademark-- Remote. Payment for redeemed
shares is normally made by Federal Reserve wire to the commercial bank account
designated in your Account Application. You may also request that payment be
made by check. We use reasonable procedures to confirm that instructions
communicated by telephone are genuine and are not liable for telephone
instructions that are reasonably believed to be genuine. Such reasonable
procedures may include recordings of telephone transactions maintained for a
reasonable period of time.

  Payment for redemption orders received prior to 5:00 p.m. Eastern time will
normally be made on the same day. Payment for shares redeemed by mail and
payment for telephone redemptions in amounts of less than $1,000 may be made by
check mailed within seven days after receipt of the redemption request in proper
form. The fund may make payment for telephone redemptions in excess of $1,000 by
check when it is considered to be in the fund's best interest to do so.

  Dividends payable up to the date of redemption on redeemed shares will
normally be paid by wire transfer on the next dividend payment date. However, if
all of the shares in your account are redeemed, you will receive dividends
payable up to the date of redemption with the proceeds of the redemption.

REDEMPTIONS BY THE FUND

If your account has been open at least one year, you have not made an additional
purchase in the account during the past six calendar months, and the value of
your account falls below $500 for three consecutive months due to redemptions or
exchanges (excluding retirement accounts), the fund has the right to redeem the
account after giving you 60 days' prior written notice. You may avoid having
your account redeemed during the notice period by bringing the account value up
to $500.

  If the fund determines that you have not provided a correct Social Security or
other tax ID number on your account application, the fund may, at its
discretion, redeem the account and distribute the proceeds to you.

  THE FUND AND ITS AGENTS RESERVE THE RIGHT AT ANY TIME TO:

  - REJECT OR CANCEL ANY PART OF ANY PURCHASE ORDER;

  - MODIFY ANY TERMS OR CONDITIONS OF PURCHASE OF SHARES OF THE FUND; OR

  - WITHDRAW ALL OR ANY PART OF THE OFFERING MADE BY THIS PROSPECTUS.

                                       A-1
<PAGE>   95
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION (continued)
- --------------------------------------------------------------------------------

PRICING OF SHARES

DETERMINATION OF NET ASSET VALUE

The price of each of the fund's shares is the fund's net asset value per share.
The fund determines the net asset value of its shares as of 5:00 p.m. Eastern
time on each day on which both the Federal Reserve Bank of New York and The Bank
of New York are open for business (business day). The fund values portfolio
securities on the basis of amortized cost, which approximates market value.

TIMING OF ORDERS

The fund prices purchase and redemption orders at the net asset value calculated
after the transfer agent receives an order in good form. If the transfer agent
receives a redemption request on a business day prior to 5:00 p.m. Eastern time,
the fund will normally wire redemption proceeds on that day. If the transfer
agent receives a redemption request after 5:00 p.m. Eastern time on a business
day of the fund, the redemption will be processed at the net asset value next
determined and the fund will normally wire proceeds on the next business day.
Shareholders will accrue dividends until the day the fund wires redemption
proceeds. The Fund may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading. The fund
reserves the right to change the time for which purchase and redemption orders
must be submitted to and received by the transfer agent for execution on the
same day on any day when the primary government securities dealers are either
closed for business or close early, or trading in money market securities is
limited due to national holidays.

TAXES

Dividends and distributions received are taxable as ordinary income or long-term
capital gains for federal income tax purposes, whether reinvested in additional
shares or taken in cash. Distributions are taxable at different rates depending
on the length of time the fund holds its assets. Every year, information will be
sent showing the amount of dividends and distributions received from the fund
during the prior year.

  Any long-term or short-term capital gains realized from redemptions of the
fund shares will be subject to federal income tax.

  The foreign, state and local tax consequences of investing in the fund may
differ materially from the federal income tax consequences described above.
Shareholders should consult their tax advisor before investing.

                                       A-2
<PAGE>   96
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

OBTAINING ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------

More information may be obtained free of charge upon request. The Statement of
Additional Information (SAI), a current version of which is on file with the
Securities and Exchange Commission (SEC), contains more details about the fund
and is incorporated by reference into the prospectus (is legally a part of this
prospectus). Annual and semiannual reports to shareholders contain additional
information about the fund's investments. The fund's annual report also
discusses the market conditions and investment strategies that significantly
affected the fund's performance during its last fiscal year.

  If you have questions about this fund, another fund in The AIM Family of
Funds--Registered Trademark-- or your account, or wish to obtain free copies
of the fund's current SAI or annual or semiannual reports, please contact us

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

<TABLE>
<S>                          <C>
BY MAIL:                     A I M Fund Services, Inc.
                             P.O. Box 4497
                             Houston, TX 77210-4497

BY TELEPHONE:                (800) 417-8837

BY E-MAIL:                   [email protected]

ON THE INTERNET:             http://www.aimfunds.com
                             (prospectuses and annual
                             and semiannual reports
                             only)
</TABLE>

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

You also can review and obtain copies of the fund's SAI, reports and other
information at the SEC's Public Reference Room in Washington, DC; on the EDGAR
database on the SEC's Internet website (http://www.sec.gov); or, after paying a
duplication fee, by sending a letter to the SEC's Public Reference Section,
Washington, DC 20549-0102 or by sending an electronic mail request to
[email protected]. Please call the SEC at 1-202-942-8090 for information about
the Public Reference Room.

- -----------------------------------
 Treasury Portfolio
 SEC 1940 Act file number: 811-2729
- -----------------------------------

[AIM LOGO APPEARS HERE]      www.aimfunds.com             INVEST WITH DISCIPLINE
                                                        --Registered Trademark--
<PAGE>   97
        TREASURY PORTFOLIO

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

        RESOURCE CLASS
        Treasury Portfolio seeks to maximize current income consistent with the
        preservation of capital and the maintenance of liquidity.

        PROSPECTUS
        DECEMBER 17, 1999

                                       This prospectus contains important
                                       information about the Resource Class
                                       of the fund. Please read it before
                                       investing and keep it for future
                                       reference.

                                       As with all other mutual fund
                                       securities, the Securities and
                                       Exchange Commission has not approved
                                       or disapproved these securities or
                                       determined whether the information
                                       in this prospectus is adequate or
                                       accurate. Anyone who tells you
                                       otherwise is committing a crime.

                                       There can be no assurance that the
                                       fund will be able to maintain a
                                       stable net asset value of $1.00 per
                                       share.

        [AIM LOGO APPEARS HERE]                  INVEST WITH DISCIPLINE
                                                 --Registered Trademark--
<PAGE>   98
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

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

<TABLE>
<S>                                       <C>

INVESTMENT OBJECTIVE AND STRATEGIES           1

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

PRINCIPAL RISKS OF INVESTING IN THE
  FUND                                        1

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

PERFORMANCE INFORMATION                       2

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

Annual Total Returns                          2

Performance Table                             2

FEE TABLE AND EXPENSE EXAMPLE                 3

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

Fee Table                                     3

Expense Example                               3

FUND MANAGEMENT                               4

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

The Advisor                                   4

Advisor Compensation                          4

OTHER INFORMATION                             4

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

Suitability for Investors                     4

Dividends and Distributions                   4

FINANCIAL HIGHLIGHTS                          5

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

SHAREHOLDER INFORMATION                     A-1

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

Distribution and Service (12b-1) Fees       A-1

Purchasing Shares                           A-1

Redeeming Shares                            A-1

Pricing of Shares                           A-2

Taxes                                       A-2

OBTAINING ADDITIONAL INFORMATION     Back Cover

- - - - - - - - - - - - - - - - - - - - - - - - - -
</TABLE>

The AIM Family of Funds, The AIM Family of Funds and Design (i.e., the AIM
logo), AIM and Design, AIM, AIM LINK, AIM Institutional Funds, aimfunds.com, La
Familia AIM de Fondos, La Familia AIM de Fondos and Design and Invest with
Discipline are registered service marks and AIM Bank Connection, AIM Funds, AIM
Funds and Design, AIM Internet Connect and AIM Investor are service marks of
A I M Management Group Inc.

No dealer, salesperson or any other person has been authorized to give any
information or to make any representations other than those contained in this
prospectus, and you should not rely on such other information or
representations.
<PAGE>   99
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

INVESTMENT OBJECTIVE AND STRATEGIES
- --------------------------------------------------------------------------------

The fund's investment objective is to maximize current income consistent with
the preservation of capital and the maintenance of liquidity.

  The fund attempts to meet this objective by investing in direct obligations of
the U.S. Treasury, including bills, notes and bonds, and repurchase agreements
secured by those obligations. The fund will maintain a weighted average maturity
of 90 days or less. The fund invests in compliance with Rule 2a-7 under the
Investment Company Act of 1940.

  The portfolio managers focus on securities they believe have favorable
prospects for current income consistent with the preservation of capital and the
maintenance of liquidity. The portfolio managers usually hold portfolio
securities to maturity, but may sell a particular security when they deem it
advisable, such as when any of the factors above materially changes.

  In anticipation of or in response to adverse market conditions, for cash
management purposes, or for defensive purposes, the fund may temporarily hold
all or a portion of its assets in cash or shares of affiliated money market
funds. As a result, the fund may not achieve its investment objective.

PRINCIPAL RISKS OF INVESTING IN THE FUND
- --------------------------------------------------------------------------------

An investment in the fund is not a deposit of a bank and is not insured or
guaranteed by the Federal Deposit Insurance Corporation or any other government
agency. Although the fund seeks to preserve the value of your investment at
$1.00 per share, it is possible to lose money by investing in the fund.
Additionally, the fund's yield will vary as the short-term securities in its
portfolio mature and the proceeds are reinvested in securities with different
interest rates.

  The following factors could reduce the fund's income and/or share price:

- - sharply rising interest rates; and

- - downgrades of credit ratings or defaults of any of the fund's holdings.

  If the seller of a repurchase agreement in which the fund invests defaults on
its obligation or declares bankruptcy, the fund may experience delays in selling
the securities underlying the repurchase agreement. As a result, the fund may
incur losses arising from decline in the value of those securities, reduced
levels of income and expenses of enforcing its rights.

  The value of your shares could be adversely affected if the computer systems
used by the fund's investment advisor and the fund's other service providers are
unable to distinguish the year 2000 from the year 1900.

  The fund's investment advisor and independent technology consultants are
working to avoid year 2000-related problems in its systems and to obtain
assurances that other service providers are taking similar steps. Year 2000
problems may also affect issuers in whose securities the fund invests.

                                        1
<PAGE>   100
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
The bar chart and table shown below provide an indication of the risks of
investing in the fund. The fund's past performance is not necessarily an
indication of its future performance.

ANNUAL TOTAL RETURNS
- --------------------------------------------------------------------------------
The following bar chart shows changes in the performance of the Resource Class
shares from year to year. Resource Class shares are not subject to sales loads.

                                    [GRAPH]

<TABLE>
<CAPTION>
                                          Annual
Year Ended                                Total
December 31                               Return
- -----------                               ------
<S>                                       <C>
1997....................................   5.39%
1998....................................   5.31%
</TABLE>

The Resource Class shares' year-to-date total return as of September 30, 1999
was 3.52%.

  During the periods shown in the bar chart, the highest quarterly return was
1.36% (quarter ended December 31, 1997) and the lowest quarterly return was
1.21% (quarter ended December 31, 1998).

PERFORMANCE TABLE

The following performance table reflects the performance of Resource Class
shares over the periods indicated.

<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS
- ------------------------------------------------------------------------------------------------------
(for the periods ended                                                          SINCE      INCEPTION
December 31, 1998)                               1 YEAR   5 YEARS   10 YEARS   INCEPTION     DATE
- ------------------------------------------------------------------------------------------------------
<S>                                              <C>      <C>       <C>        <C>         <C>
Resource Class                                    5.31%     --         --        5.31%      03/16/96
- ------------------------------------------------------------------------------------------------------
</TABLE>

Resource Class share's seven-day yield on December 31, 1998 was 4.65%. For the
current seven-day yield, call (800) 825-6858.

                                        2
<PAGE>   101
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FEE TABLE AND EXPENSE EXAMPLE
- --------------------------------------------------------------------------------

FEE TABLE

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

<TABLE>
<CAPTION>
SHAREHOLDER FEES
- - - - - - - - - - - - - - - - - - - - - - - - - -
(fees paid directly from
your investment)                RESOURCE CLASS
- ----------------------------------------------
<S>                             <C>
Maximum Sales Charge (Load)
Imposed on Purchases
(as a percentage of
offering price)                      None

Maximum Deferred
Sales Charge (Load)
(as a percentage of
original purchase
price or redemption
proceeds, whichever is less)         None
- ----------------------------------------------
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- -- - - - - - - - - - - - - - - - - - - - - - - -
(expenses that are deducted
from fund assets)                 RESOURCE CLASS
- --------------------------------------------------
<S>                               <C>
Management Fees                          0.06%
Distribution and/or Service
(12b-1) Fees                             0.20
Other Expenses                           0.03
Total Annual Fund
Operating Expenses                       0.29
Fee Waiver(1)                            0.04
Net Expenses                             0.25
- --------------------------------------------------
</TABLE>

(1) The distributor has contractually agreed to waive 0.04% of the Rule 12b-1
    distribution plan fee.

You should also consider the effect of any account fees charged by the financial
institution managing the account.

EXPENSE EXAMPLE

This example is intended to help you compare the costs of investing in the
Resource Class of 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 gross operating expenses remain the same. To the extent fees are waived
or expenses are reimbursed, the expenses will be lower. Although your actual
returns and costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
                 1 YEAR   3 YEARS   5 YEARS   10 YEARS
- ------------------------------------------------------
<S>              <C>      <C>       <C>       <C>
Resource Class    $30       $93      $163       $368
- ------------------------------------------------------
</TABLE>

                                        3
<PAGE>   102
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FUND MANAGEMENT
- --------------------------------------------------------------------------------

THE ADVISOR

A I M Advisors, Inc. (the advisor) serves as the fund's investment advisor and
is responsible for its day-to-day management. The advisor is located at 11
Greenway Plaza, Suite 100, Houston, Texas 77046-1173. The advisor supervises all
aspects of the fund's operations and provides investment advisory services to
the fund, including obtaining and evaluating economic, statistical and financial
information to formulate and implement investment programs for the fund.

  The advisor has acted as an investment advisor since its organization in 1976.
Today, the advisor, together with its subsidiaries, advises or manages over 125
investment portfolios, including the fund, encompassing a broad range of
investment objectives.

ADVISOR COMPENSATION

During the fiscal year ended August 31, 1999, the advisor received compensation
of 0.06% of average daily net assets.

OTHER INFORMATION
- --------------------------------------------------------------------------------

SUITABILITY FOR INVESTORS

The Resource Class of the fund is intended for use primarily by customers of
banks, certain broker-dealers and other institutions (institutions). It is
expected that the shares of the Resource Class may be particularly suitable
investments for corporate cash managers, municipalities or other public
entities. Individuals, corporations, partnerships and other businesses that
maintain qualified accounts at an institution may invest in shares of the
Resource Class. Each institution will render administrative support services to
its customers who are the beneficial owners of the shares of the Resource Class.
Such services include, among other things, establishment and maintenance of
shareholder accounts and records; assistance in processing purchase and
redemption transactions in shares of the Resource Class; providing periodic
statements showing a client's account balance in shares of the Resource Class;
distribution of fund proxy statements, annual reports and other communications
to shareholders whose accounts are serviced by the institution; and such other
services as the fund may reasonably request. Institutions will be required to
certify to the fund that they comply with applicable state law regarding
registration as broker-dealers, or that they are exempt from such registration.

  The Resource Class is designed to be a convenient and economical way to invest
in an open-end diversified money market fund. It is anticipated that most
investors will perform their own subaccounting.

  Investors in the Resource Class have the opportunity to receive a somewhat
higher yield than might be obtainable through direct investment in money market
instruments, and enjoy the benefits of diversification, economies of scale and
same-day liquidity. Generally, higher interest rates can be obtained on the
purchase of very large blocks of money market instruments. Of course, any such
relative increase in interest rates may be offset to some extent by the
operating expenses of the Resource Class.

DIVIDENDS AND DISTRIBUTIONS

The fund expects that its distributions will consist primarily of ordinary
income.

DIVIDENDS

The fund generally declares dividends on each business day and pays dividends
monthly. A business day is any day on which both the Federal Reserve Bank of New
York and The Bank of New York, the fund's custodian, are open for business.

  Dividends are paid to settled shares of the fund as of 5:00 p.m. Eastern time.
Generally, shareholders whose purchase orders have been received by the fund
prior to 5:00 p.m. Eastern time and shareholders whose redemption proceeds have
not been wired to them on any business day are eligible to receive dividends on
that business day. The dividend declared on any day preceding a non-business day
of the fund will include the income accrued on such non-business day. Dividends
and distributions are paid in cash unless the shareholder has elected to have
such dividends and distributions reinvested in the form of additional full and
fractional shares at the net asset value.

CAPITAL GAINS DISTRIBUTIONS

The fund generally distributes net realized capital gains (including net
short-term capital gains), if any, annually. The fund does not expect to realize
any long-term capital gains and losses.

                                        4
<PAGE>   103
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand the financial
performance of the Resource Class. Certain information reflects financial
results for a single fund share.

  The total returns in the table represent the rate that 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 KPMG LLP, whose report, along with the
fund's financial statements, is included in the fund's annual report, which is
available upon request.

<TABLE>
<CAPTION>
                                                                    RESOURCE CLASS
                                                  -------------------------------------------------
                                                                                     FOR THE PERIOD
                                                                                     MARCH 12, 1996
                                                                                        THROUGH
                                                        YEAR ENDED AUGUST 31,          AUGUST 31,
                                                    1999         1998       1997          1996
- ---------------------------------------------------------------------------------------------------
<S>                                               <C>          <C>        <C>        <C>
Net asset value, beginning of period              $   1.00     $   1.00   $   1.00      $  1.00
Income from investment operations:
  Net investment income                               0.05         0.05       0.05         0.03
Less distributions:
  Dividends from net investment income               (0.05)       (0.05)     (0.05)       (0.03)
Net asset value, end of period                    $   1.00     $   1.00   $   1.00      $  1.00
Total return                                          4.80%        5.47%      5.30%        2.43%
- ---------------------------------------------------------------------------------------------------
Ratios/supplemental data:
- ------------------------------------------------------------------  -------------------------------
Net assets, end of period (000s omitted)          $359,101     $455,961   $237,123      $33,339
Ratio of expenses to average net assets(a)            0.25%(b)     0.24%      0.25%        0.25%(c)
Ratio of net investment income to average net
  assets(d)                                           4.69%(b)     5.34%      5.19%        5.07%(c)
- ---------------------------------------------------------------------------------------------------
</TABLE>

(a) After fee waivers and/or expense reimbursements. Ratios of expenses to
    average net assets prior to fee waivers and/or expense reimbursements were
    0.29%, 0.28%, 0.29%, and 0.29% (annualized) for the periods 1999-1996,
    respectively.
(b) Ratios based on average net assets of $369,242,180.
(c) Annualized.
(d) After fee waivers and/or expense reimbursements. Ratios of net investment
    income to average net assets prior to fee waivers and/or expense
    reimbursements were 4.65%, 5.30%, 5.15%, and 5.03% (annualized) for the
    periods 1999-1996, respectively.

                                        5
<PAGE>   104
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION
- --------------------------------------------------------------------------------

The fund currently offers six classes of shares all of which share a common
investment objective and portfolio of investments. The six classes differ only
with respect to distribution arrangements for different categories of investors.

DISTRIBUTION AND SERVICE (12b-1) FEES

The fund has adopted a 12b-1 plan with respect to the Resource Class that allows
the fund to pay distribution fees to Fund Management Company (distributor) for
the sale and distribution of its shares and fees for services provided to
shareholders. Because the fund pays these fees out of its assets on an ongoing
basis, over time these fees will increase the cost of your investment and may
cost you more than paying other types of sales charges.

PURCHASING SHARES

The minimum initial investment in the Resource Class is $10,000. No minimum
amount is required for subsequent investments in the fund, nor are minimum
balances required.

  Purchase orders will be accepted for execution on the day the order is placed,
provided that the order is properly submitted and received by the transfer agent
prior to 5:00 p.m. Eastern time on a business day of the fund. Purchase orders
received after such time will be processed at the next day's net asset value.
You may purchase shares by submitting an Account Application to the fund's
transfer agent, A I M Fund Services, Inc. (transfer agent) at P.O. Box 4497,
Houston, Texas 77210-4497 prior to your initial purchase of shares. You must
open a fund account through an institution in accordance with procedures
established by such institution. A purchase order is considered received at the
time The Bank of New York receives federal funds (member bank deposits with a
Federal Reserve Bank) for the order, provided the transfer agent has received
notice of the order. Subsequent purchases of shares of the funds may also be
made via AIM LINK--Registered Trademark-- Remote, a personal computer
application software product.

  If you propose to open a fund account with an institution, you should consult
with a representative of such institution to obtain a description of the rules
governing such an account. A statement with regard to your investment in the
Resource Class is supplied periodically, and confirmations of all transactions
for your account are provided by the institution promptly upon request. In
addition, proxies, periodic reports and other information from the institution
with regard to your shares of the Resource Class will be sent to you.

  You may place an order for the purchase of shares of the Resource Class with
the institution. The institution is responsible for the prompt transmission of
the order to the transfer agent. The fund is normally required to make immediate
settlement in federal funds for portfolio securities purchased. Accordingly,
payment for shares of the Resource Class purchased by institutions on behalf of
their clients must be in federal funds. If an order to purchase shares is paid
for other than in federal funds, the order may be delayed up to two business
days while the institution completes the conversion into federal funds.

REDEEMING SHARES

You may redeem any or all of your shares at the net asset value next determined
after receipt of a redemption request in proper form by the fund. There is no
charge for redemption. Redemption requests with respect to shares of the
Resource Class are normally made through your institution.

  You may request a redemption by calling the transfer agent at (800) 825-6858,
or by using AIM LINK--Registered Trademark-- Remote. Payment for redeemed shares
is normally made by Federal Reserve wire to the commercial bank account
designated in your Account Application. You may also request that payment be
made by check. We use reasonable procedures to confirm that instructions
communicated by telephone are genuine and are not liable for telephone
instructions that are reasonably believed to be genuine. Such reasonable
procedures may include recordings of telephone transactions maintained for a
reasonable period of time.

  Payment for redemption orders received prior to 5:00 p.m. Eastern time will
normally be made on the same day. Payment for shares redeemed by mail and
payment for telephone redemptions in amounts of less than $1,000 may be made by
check mailed within seven days after receipt of the redemption request in proper
form. The fund may make payment for telephone redemptions in excess of $1,000 by
check when it is considered to be in the fund's best interest to do so.

  Dividends payable up to the date of redemption on redeemed shares will
normally be paid by wire transfer on the next dividend payment date. However, if
all of the shares in your account are redeemed, you will receive dividends
payable up to the date of redemption with the proceeds of the redemption.

REDEMPTIONS BY THE FUND

If your account has been open at least one year, you have not made an additional
purchase in the account during the past six calendar months, and the value of
your account falls below $500 for three consecutive months due to redemptions or
exchanges (excluding retirement accounts), the fund has the right to redeem the
account after giving you 60 days' prior written notice. You may avoid having
your account redeemed during the notice period by bringing the account value up
to $500.

  If the fund determines that you have not provided a correct Social Security or
other tax ID number on your account application, the fund may, at its
discretion, redeem the account and distribute the proceeds to you.

                                       A-1
<PAGE>   105
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

SHAREHOLDER INFORMATION (continued)
- --------------------------------------------------------------------------------

  THE FUND AND ITS AGENTS RESERVE THE RIGHT AT ANY TIME TO:

  - REJECT OR CANCEL ANY PART OF ANY PURCHASE ORDER;

  - MODIFY ANY TERMS OR CONDITIONS OF PURCHASE OF SHARES OF THE FUND; OR

  - WITHDRAW ALL OR ANY PART OF THE OFFERING MADE BY THIS PROSPECTUS.

PRICING OF SHARES

DETERMINATION OF NET ASSET VALUE

The price of each of the fund's shares is the fund's net asset value per share.
The fund determines the net asset value of its shares as of 5:00 p.m. Eastern
time on each day on which both the Federal Reserve Bank of New York and The Bank
of New York are open for business (business day). The fund values portfolio
securities on the basis of amortized cost, which approximates market value.

TIMING OF ORDERS

The fund prices purchase and redemption orders at the net asset value calculated
after the transfer agent receives an order in good form. If the transfer agent
receives a redemption request on a business day prior to 5:00 p.m. Eastern time,
the fund will normally wire redemption proceeds on that day. If the transfer
agent receives a redemption request after 5:00 p.m. Eastern time on a business
day of the fund, the redemption will be processed at the net asset value next
determined and the fund will normally wire proceeds on the next business day.
Shareholders will accrue dividends until the day the fund wires redemption
proceeds. The Fund may postpone the right of redemption only under unusual
circumstances, as allowed by the Securities and Exchange Commission, such as
when the New York Stock Exchange restricts or suspends trading. The fund
reserves the right to change the time for which purchase and redemption orders
must be submitted to and received by the transfer agent for execution on the
same day on any day when the primary government securities dealers are either
closed for business or close early, or trading in money market securities is
limited due to national holidays.

TAXES

Dividends and distributions received are taxable as ordinary income or long-term
capital gains for federal income tax purposes, whether reinvested in additional
shares or taken in cash. Distributions are taxable at different rates depending
on the length of time the fund holds its assets. Every year, information will be
sent showing the amount of dividends and distributions received from the fund
during the prior year.

  Any long-term or short-term capital gains realized from redemptions of the
fund shares will be subject to federal income tax.

  The foreign, state and local tax consequences of investing in the fund may
differ materially from the federal income tax consequences described above.
Shareholders should consult their tax advisor before investing.

                                       A-2
<PAGE>   106
                               ------------------
                               TREASURY PORTFOLIO
                               ------------------

OBTAINING ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------

More information may be obtained free of charge upon request. The Statement of
Additional Information (SAI), a current version of which is on file with the
Securities and Exchange Commission (SEC), contains more details about the fund
and is incorporated by reference into the prospectus (is legally a part of this
prospectus). Annual and semiannual reports to shareholders contain additional
information about the fund's investments. The fund's annual report also
discusses the market conditions and investment strategies that significantly
affected the fund's performance during its last fiscal year.

  If you have questions about this fund, another fund in The AIM Family of
Funds--Registered Trademark-- or your account, or wish to obtain free copies
of the fund's current SAI or annual or semiannual reports, please contact us

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

<TABLE>
<S>                          <C>
BY MAIL:                     A I M Fund Services, Inc.
                             P. O. Box 4497
                             Houston, TX 77210-4497

BY TELEPHONE:                (800) 825-6858

BY E-MAIL:                   [email protected]

ON THE INTERNET:             http://www.aimfunds.com
                             (prospectuses and annual
                             and semiannual reports
                             only)
</TABLE>

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

You also can review and obtain copies of the fund's SAI, reports and other
information at the SEC's Public Reference Room in Washington, DC; on the EDGAR
database on the SEC's Internet website (http://www.sec.gov); or, after paying a
duplication fee, by sending a letter to the SEC's Public Reference Section,
Washington, DC 20549-0102 or by sending an electronic mail request to
[email protected]. Please call the SEC at 1-202-942-8090 for information about
the Public Reference Room.

- -----------------------------------
 Treasury Portfolio
 SEC 1940 Act file number: 811-2729
- -----------------------------------

[AIM LOGO APPEARS HERE]       www.aimfunds.com          INVEST WITH DISCIPLINE
                                                        --Registered Trademark--


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