SHORT TERM INVESTMENTS TRUST, 497, 1998-12-21

SHORT TERM INVESTMENTS TRUST
497, 1998-12-21

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SHORT-TERM
INVESTMENTS TRUST
Prospectus
- --------------------------------------------------------------------------------

TREASURY The Treasury TaxAdvantage Portfolio is a money
TAXADVANTAGE market fund whose investment objective is the
PORTFOLIO maximization of current income to the extent consistent
with the preservation of capital and the maintenance of
CASH liquidity. The Treasury TaxAdvantage Portfolio seeks to
MANAGEMENT achieve its objective by investing in direct
CLASS obligations of the U.S. Treasury. The Treasury
TaxAdvantage Portfolio's investment strategy is
intended to enable the Portfolio to provide its
DECEMBER 18, 1998 shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions. The
instruments purchased by the Treasury TaxAdvantage
Portfolio will have maturities of 397 days or less.
The Treasury TaxAdvantage Portfolio is a series
portfolio of Short-Term Investments Trust (the
"Trust"), an open-end diversified, series, management
investment company. This Prospectus relates solely to
the Cash Management Class of the Treasury TaxAdvantage
Portfolio, a class of shares designed to be a
convenient vehicle in which customers of banks, certain
broker-dealers and other financial institutions can
invest short-term cash reserves.

THESE SECURITIES HAVE NOT BEEN APPROVED OR
DISAPPROVED BY THE SECURITIES AND EXCHANGE COMMISSION
NOR HAS THE SECURITIES AND EXCHANGE COMMISSION PASSED
UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

THIS PROSPECTUS SETS FORTH BASIC INFORMATION THAT
A PROSPECTIVE INVESTOR SHOULD KNOW BEFORE INVESTING IN
SHARES OF THE CASH MANAGEMENT CLASS OF THE TREASURY
TAXADVANTAGE PORTFOLIO AND SHOULD BE READ AND RETAINED
FOR FUTURE REFERENCE. A STATEMENT OF ADDITIONAL
INFORMATION, DATED DECEMBER 18, 1998, HAS BEEN FILED
WITH THE UNITED STATES SECURITIES AND EXCHANGE
COMMISSION (THE "SEC") AND IS HEREBY INCORPORATED BY
REFERENCE. FOR A COPY OF THE STATEMENT OF ADDITIONAL
INFORMATION WITHOUT CHARGE, WRITE TO THE ADDRESS ABOVE
OR CALL (800) 877-7745. THE SEC MAINTAINS A WEB SITE AT
HTTP://WWW.SEC.GOV THAT CONTAINS THE STATEMENT OF
ADDITIONAL INFORMATION, MATERIAL INCORPORATED BY
REFERENCE, AND OTHER INFORMATION REGARDING THE TRUST.

THE TRUST'S SHARES ARE NOT DEPOSITS OR OBLIGATIONS
OF, OR GUARANTEED OR ENDORSED BY, ANY BANK, AND THE
TRUST'S SHARES ARE NOT FEDERALLY INSURED OR GUARANTEED
BY THE U.S. GOVERNMENT, THE FEDERAL DEPOSIT INSURANCE
CORPORATION, THE FEDERAL RESERVE BOARD OR ANY OTHER
AGENCY. THERE CAN BE NO ASSURANCE THAT THE TREASURY
TAXADVANTAGE PORTFOLIO WILL BE ABLE TO MAINTAIN A
STABLE NET ASSET VALUE OF $1.00 PER SHARE. SHARES OF
THE TRUST INVOLVE INVESTMENT RISKS, INCLUDING THE
POSSIBLE LOSS OF PRINCIPAL.

[AIM LOGO]

Fund Management Company

11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-7745
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SUMMARY

THE PORTFOLIO AND ITS INVESTMENT OBJECTIVE

The Trust is an open-end diversified series management investment company.
This Prospectus relates to the Cash Management Class (the "Class") of the
Treasury TaxAdvantage Portfolio (the "Portfolio"). The Portfolio is a money
market fund which invests in direct obligations of the U.S. Treasury. The
instruments purchased by the Portfolio will have maturities of 397 days or less.
The investment objective of the Portfolio is the maximization of current income
to the extent consistent with the preservation of capital and the maintenance of
liquidity. The Portfolio's investment strategy is intended to enable the
Portfolio to provide its shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions.

Pursuant to separate prospectuses, the Trust also offers other classes of
shares of beneficial interest representing interests in the Portfolio: the
Institutional Class, the Personal Investment Class, the Private Investment
Class, the Reserve Class and the Resource Class. Such classes have different
distribution arrangements and are designed for different types of investors. The
Trust also offers shares of several classes representing interests in each of
two other portfolios, the Government & Agency Portfolio and the Treasury
Portfolio, pursuant to separate prospectuses. The portfolios of the Trust are
referred to collectively as "Portfolios."

Because the Trust declares dividends on a daily basis, shares of each class
of the Portfolio have the same net asset value (proportionate interest in the
net assets of the Portfolio) and bear equally those expenses, such as the
advisory fee, that are allocated to the Portfolio as a whole. All classes of the
Portfolio share a common investment objective and portfolio of investments.
However, different classes of the Portfolio have different shareholder
qualifications, and are separately allocated certain class expenses, such as
those associated with the distribution of their shares. Therefore, each class
will have a different dividend payment and a different yield.

INVESTORS IN THE CLASS

The Class is designed to be a convenient vehicle in which customers of
banks, certain broker-dealers and other financial institutions can invest in a
diversified open-end money market fund.

PURCHASE OF SHARES

Shares of the Class that are offered hereby are sold at net asset value.
The minimum initial investment in the Class is $1,000,000. There is no minimum
amount for subsequent investments. Payment for shares of the Class purchased
must be in funds immediately available to the Trust. See "Purchase of Shares."

REDEMPTION OF SHARES

Redemptions may be made without charge at net asset value. Payment for
redeemed shares of the Class for which redemption orders are received prior to
3:00 p.m. Eastern Time will normally be made on the same day. See "Redemption of
Shares."

DIVIDENDS

The net income of the Portfolio is declared as a dividend daily to
shareholders of record immediately after 3:00 p.m. Eastern Time. Dividends are
paid monthly by check or wire transfer unless the shareholder has previously
elected to have such dividends automatically reinvested in additional shares of
the Class. Information concerning the amount of the dividends declared on any
particular day will normally be available by 4:00 p.m. Eastern Time on that day.
See "Dividends."

CONSTANT NET ASSET VALUE

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will normally remain constant at $1.00. AN INVESTMENT IN THE PORTFOLIO IS NOT
INSURED OR GUARANTEED BY THE U.S. GOVERNMENT, AND THERE IS NO ASSURANCE THAT THE
PORTFOLIO WILL BE ABLE TO MAINTAIN A STABLE NET ASSET VALUE. See "Net Asset
Value."

INVESTMENT ADVISOR

A I M Advisors, Inc. ("AIM") serves as the Trust's investment advisor and
receives a fee based on the Trust's average daily net assets. During the fiscal
year ended August 31, 1998, the Trust paid AIM advisory fees with respect to the
Portfolio which represented 0.12% of the average daily net assets of the
Portfolio. AIM is primarily engaged in the business of acting as manager or
advisor to investment companies. Under an Administrative Services Agreement, AIM
may be reimbursed by the Trust for its costs of performing certain accounting
and other administrative services for the Trust. See "Management of the
Trust -- Investment Advisor" "-- Administrative Services." Under a Transfer
Agency and Service Agreement, A I M Fund Services, Inc., ("Transfer Agent"),
AIM's wholly owned subsidiary and a registered transfer agent, receives a fee
for its provision of transfer agency, dividend distribution and disbursement,
and shareholder services to the Trust. See "General Information -- Transfer
Agent and Custodian."

DISTRIBUTOR AND DISTRIBUTION PLAN

SPECIAL RISK CONSIDERATIONS

The Portfolio may borrow money and enter into reverse repurchase agreements
for temporary or emergency purposes, and may purchase securities for delayed
delivery. Accordingly, an investment in the Portfolio may entail somewhat
different risks from an investment in an investment company that does not engage
in such practices. There can be no assurance that the Portfolio will be able to
maintain a stable net asset value of $1.00 per share. See "Investment Program."

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 is a service
mark of A I M Management Group Inc.

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TABLE OF FEES AND EXPENSES

ANNUAL PORTFOLIO OPERATING EXPENSES -- CASH MANAGEMENT CLASS
(AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management fees (after fee waivers)**..................... 0.12%
12b-1 fees (after fee waivers)**.......................... 0.08%
Other expenses (estimated):
Custodian fees......................................... 0.01%
Other.................................................. 0.07%
------
Total other expenses.............................. 0.08%
------
Total portfolio operating expenses -- Cash Management
Class**................................................ 0.28%
======
</TABLE>

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EXAMPLE

An investor in the Class would pay the following expenses on a $1,000
investment, assuming (1) a 5% annual return and (2) redemption at the end of
each time period.

<TABLE>
<S> <C>
1 year..................................................... $ 3
3 years.................................................... $ 9
</TABLE>

The Table of Fees and Expenses is designed to assist an investor in
understanding the various costs and expenses that an investor in the Class will
bear directly or indirectly. (For more complete descriptions of the various
costs and expenses, see "Management of the Trust" below.) The "Total portfolio
operating expenses -- Cash Management Class" is based upon costs and the
estimated size of the Class and fees to be charged for the current fiscal
period. The "Other expenses" and "12b-1 fees" figures are based upon estimated
costs and the estimated size of the Class and the Portfolio and estimated fees
to be charged for the current fiscal period. Thus, actual expenses may be
greater or less than such estimates. The Table of Fees and Expenses reflects
voluntary waivers for the Class. Future waivers of fees (if any) may vary from
the figures reflected in the Table of Fees and Expenses. To the extent any
service providers assume additional expenses of the Class, such assumption of
additional expenses will have the effect of lowering the Class's overall expense
ratio and increasing its yield to investors. Beneficial owners of shares of the
Class should also consider the effect of any charges imposed by the institution
maintaining their accounts.

The example in the Table of Fees and Expenses assumes that all dividends
and distributions are reinvested and that the amounts listed under "Annual
Portfolio Operating Expenses -- Cash Management Class" remain the same in the
years shown.

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The example shown in the above table is based on the amounts listed under
"Annual Portfolio Operating Expenses." THE EXAMPLE SHOULD NOT BE CONSIDERED TO
BE AN ACCURATE REPRESENTATION OF PAST OR FUTURE EXPENSES AND ACTUAL EXPENSES MAY
BE GREATER OR LESSER THAN THOSE SHOWN.

SUITABILITY FOR INVESTORS

The Class is intended for use primarily by customers of banks, certain
broker-dealers and other financial institutions who seek a convenient vehicle in
which to invest in an open-end diversified money market fund. The Portfolio's
investment strategy is intended to provide its shareholders with dividends that
are exempt from state and local income taxation in certain jurisdictions. The
minimum initial investment is $1,000,000.

Investors in the 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 Class.

Because the Portfolio invests in direct obligations of the U.S. Treasury it
may be considered to have somewhat less risk than many other money market funds
and yields on the Portfolio may be expected to be somewhat lower than many other
money market funds. However, the possible exemption from state and local income
taxation with respect to dividends paid by the Portfolio may enable shareholders
to achieve an after-tax return comparable to or higher than that obtained from
other money market funds, which may provide an advantage to some shareholders.

INVESTMENT PROGRAM

INVESTMENT OBJECTIVE

The investment objective of the Portfolio is the maximization of current
income to the extent consistent with the preservation of capital and the
maintenance of liquidity. The Portfolio intends to provide its shareholders with
dividends that are exempt from state and local income taxation in certain
jurisdictions. The Portfolio seeks to achieve its objective by investing in
direct obligations of the U.S. Treasury. 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 available on money market instruments of
lesser quality.

INVESTMENT POLICIES

The Portfolio invests exclusively in direct obligations of the U.S.
Treasury, which include Treasury bills, notes and bonds. The market values of
the money market instruments held by the Portfolio will be affected by changes
in the yields available on similar securities. If yields have increased since a
security was purchased, the market value of such security will generally have
decreased. Conversely, if yields have decreased, the market value of such
security will generally have increased.

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. The Portfolio will
only borrow money or enter into reverse repurchase agreements for temporary or
emergency purposes, such as to facilitate the orderly sale of portfolio
securities to accommodate abnormally heavy redemption requests should they
occur. Borrowing will not be made for leverage purposes. 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. 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

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encountered, could cause a reduction in the net asset value of the Portfolio's
shares. Reverse repurchase agreements are considered to be borrowings under the
1940 Act.

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 delivery" 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, 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 purchase 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 market. 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. 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. 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, however, the high turnover rate should not adversely affect the
Portfolio's net income.

INVESTMENT IN OTHER INVESTMENT COMPANIES. The Trust is permitted to invest
in 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 investment policies described above may be changed by the Board of
Trustees without the affirmative vote of a majority of the outstanding shares of
beneficial interest of the Trust.

INVESTMENT RESTRICTIONS

The Portfolio's investment program is subject to a number of investment
restrictions which reflect self-imposed standards as well as federal and state
regulatory limitations. These restrictions are designed to minimize certain
risks associated with investing in specified types of securities or engaging in
certain transactions and to limit the amount of the Portfolio's assets which may
be concentrated in any specific industry or issuer. The most significant of
these restrictions provides that the Portfolio will not:

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. The Portfolio will not purchase
securities while borrowings in excess of 5% of its total
assets are outstanding.

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The foregoing investment restriction of the Portfolio (as well as certain
others set forth in the Statement of Additional Information) is a matter of
fundamental policy which may not be changed without the affirmative vote of a
majority of the outstanding shares of the Portfolio.

In addition to the restrictions described above, the Portfolio must also
comply with the requirements of Rule 2a-7 under the 1940 Act, as such Rule may
be amended from time to time, which governs the operations of money market
funds, and may be more restrictive than the policies described herein. A
description of further investment restrictions applicable to the Portfolio is
contained in the Statement of Additional Information.

PURCHASE OF SHARES

Shares of the Class are sold on a continuing basis at their net asset value
next determined after an order has been received by the Portfolio. As discussed
below, the Trust reserves the right to reject any purchase order. Although there
is no sales charge imposed on the purchase of shares of the Class, banks or
other institutions may charge a recordkeeping, account maintenance or other fee
to their customers, and beneficial holders of the shares of the Class should
consult with the institutions maintaining their accounts to obtain a schedule of
applicable fees. To facilitate the investment of proceeds of purchase orders,
investors are urged to place their orders as early in the day as possible.
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 3:00 p.m. Eastern Time on a business day of the Portfolio. Purchase
orders received after such time will be processed at the next day's net asset
value. Following the initial investment, subsequent purchases of shares of the
Class may also be made via AIM LINK--Registered Trademark-- Remote, a personal
computer application software product. Shares of the Class will earn the
dividend declared on the effective date of purchase.

A "business day of the Portfolio" is any day on which both the Federal
Reserve Bank of New York and The Bank of New York, the Trust's custodian bank,
are open for business. The Portfolio, however, reserves the right to change the
time for which purchase and redemption requests must be submitted to the
Portfolio for execution on the same day or any day when the U.S. primary
broker-dealer community is closed for business or trading is restricted due to
national holiday. It is expected that The Bank of New York and the Federal
Reserve Bank of New York will be closed during the next twelve months on
Saturdays and Sundays, and on the observed holidays of New Year's Day, Martin
Luther King, Jr.'s Birthday, Presidents' Day, Memorial Day, Independence Day,
Labor Day, Columbus Day, Veterans' Day, Thanksgiving Day and Christmas Day.

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

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customers. An investor who proposes to open a Portfolio account with an
Institution should consult with a representative of such Institution to obtain a
description of the rules governing such an account. The Institution holds shares
of the Class registered in its name, as agent for the customer, on the books of
the Institution. A statement with regard to the customer's shares of the Class
is supplied to the customer periodically, and confirmations of all transactions
for the account of the customer are provided by the Institution to the customer
promptly upon request. In addition, the Institution sends to each customer
proxies, periodic reports and other information with regard to the customer's
shares of the Class. The customer's shares of the Class are fully assignable and
subject to encumbrance by the customer.

All agreements which relate to a customer's account with an Institution are
with the Institution. 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 Class directly, except through reinvestment of
dividends and distributions.

Orders for the purchase of shares of the Class are placed by the investor
with the Institution. The Institution is responsible for the prompt transmission
of the order to the Trust. The Portfolio will normally be required to make
immediate settlement in federal funds (member bank deposits with a Federal
Reserve Bank) for portfolio securities purchased. Accordingly, payment for
shares of the Class purchased by Institutions on behalf of their customers must
be in federal funds. If an investor's order to purchase shares of the Class is
paid for other than in federal funds, the Institution, acting on behalf of the
investor, completes the conversion into federal funds (which may take two
business days), or itself advances federal funds prior to conversion, and
promptly transmits the order and payment in the form of federal funds to the
Transfer Agent.

Subject to the conditions stated above and to the Trust's right to reject
any purchase order, orders will be accepted (i) when payment for shares of the
Class purchased is received by The Bank of New York, the Trust's custodian bank,
in the form described above and notice of such order is provided to the Transfer
Agent or (ii) at the time the order is placed, if the Portfolio is assured of
payment. Shares of the Class purchased by orders which are accepted prior to
3:00 p.m. Eastern Time will earn the dividend declared on the date of purchase.

Any request for a correction to a transaction of Portfolio shares must be
submitted in writing to the Transfer Agent. The Transfer Agent 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.

Federal Reserve wires should be sent as early as possible in order to
facilitate crediting to the shareholder's account. 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 returned to the sending
Institution. An order must specify that it is for the purchase of Shares of the
"Cash Management Class of the Treasury TaxAdvantage Portfolio," otherwise any
funds received will be returned to the sending Institution.

The Trust reserves the right in its sole discretion to withdraw all or any
part of the offering made by this Prospectus or to reject any purchase order.

REDEMPTION OF SHARES

A shareholder may redeem any or all of its shares of the Class at the net
asset value next determined after receipt of the redemption request in proper
form by the Trust. Redemption requests with respect to the Class may also be
made via AIM LINK--Registered Trademark-- Remote. Normally, the net asset value
per share of the Portfolio will remain constant at $1.00. See "Net Asset Value."
Redemption requests with respect to shares of the Class are normally made
through a customer's Institution.

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by a shareholder. If a redemption request is received by the Transfer Agent
prior to 3:00 p.m. Eastern Time on a business day of the Portfolio, the
redemption will be effected at the net asset value next determined on such day
and the shares of the Class to be redeemed will not receive the dividend
declared on the effective date of the redemption. If a redemption request is
received by the Transfer Agent after 3:00 p.m. Eastern Time or on other than a
business day of the Portfolio, the redemption will be effected at the net asset
value of the Portfolio determined as of 3:00 p.m. Eastern Time on the next
business day of the Portfolio, and the proceeds of such redemption will normally
be wired on the effective day of the redemption. The Portfolio reserves the
right to change the time for which redemption requests must be submitted to and
received by the Transfer Agent for execution on the same day on any day when the
U.S. primary broker-dealer community is closed for business or trading is
restricted due to national holidays.

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 a trust company. Additional
documentation may be required when deemed appropriate by the Trust or the
Transfer Agent.

Shareholders may request a redemption by telephone. Neither the Transfer
Agent nor FMC will be liable for any loss, expense or cost arising out of any
telephone redemption request effected in accordance with the authorization set
forth in the Account Application if they reasonably believe such request to be
genuine but may in certain cases be liable for losses due to unauthorized or
fraudulent transactions if they do not follow reasonable procedures for
verification of telephone transactions. Such reasonable procedures for
verification of telephone transactions may include recordings of telephone
transactions (maintained for six months), and mailings of confirmations promptly
after the transaction.

Payment for shares of the Class 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 Trust may
make payment for telephone redemptions in excess of $1,000 by check when it is
considered to be in the Portfolio's best interest to do so.

In certain cases, the Trust may call for the redemption of, or refuse to
transfer or issue, shares of the Class in order to comply with the law or to
further the purposes for which the Trust is formed. If a transfer or redemption
of shares of the Class causes the value of shares of the Class in an account to
be less than $500, the Trust may cause the remaining shares to be redeemed.

DIVIDENDS

Dividends from the net income of the Portfolio are declared daily to
shareholders of record of each class of the Portfolio as of immediately after
3:00 p.m. Eastern Time on the day of declaration. Net income for dividend
purposes is determined daily as of 3:00 p.m. Eastern Time. The dividend accrued
and paid for each class will consist of (a) income of the Portfolio, the
allocation of which is based upon such class's pro rata share of the total
outstanding shares representing an interest in the Portfolio, less (b) Portfolio
expenses, such as custodian fees, trustees' fees, accounting and legal expenses,
based upon such class's pro rata share of the net assets of the Portfolio, less
(c) expenses directly attributable to such class, such as distribution expenses,
if any, and transfer agency fees. Although realized gains and losses on the
assets of the Portfolio are reflected in its net asset value, they are not
expected to be of an amount which would affect its $1.00 per share net asset
value for purposes of purchases and redemptions. See "Net Asset Value."
Distributions from net realized short-term gains may be declared and paid yearly
or more frequently. See "Taxes." The Portfolio does not expect to realize any
long-term capital gains or losses.

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. A shareholder may elect to have all dividends automatically
reinvested in additional full and fractional shares of the Class at the net
asset value as of 3:00 p.m. Eastern Time on the last business day of the month.
Such election, or any revocation thereof, must be made in writing by the
Institution to the Transfer Agent at P.O. Box 4497, Houston, TX 77210-4497, and
will become effective with dividends paid after its receipt by the Transfer
Agent. If a shareholder redeems all

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the shares of the Class in its 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.

The Portfolio uses its best efforts to maintain the net asset value per
share at $1.00 for purposes of sales and redemptions. See "Net Asset Value."
Should the Trust incur or anticipate any unusual expense, loss or depreciation
which could adversely affect the income or net asset value of the Portfolio, the
Trust's 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 the then
prevailing circumstances. For example, under such unusual circumstances, the
Board of Trustees might reduce or suspend the daily dividend in order to prevent
to the extent possible the net asset value per share of the Portfolio from being
reduced below $1.00. Thus, such expenses, losses or depreciation may result in a
shareholder receiving no dividends for the period during which it held its
shares of the Class and cause such a shareholder to receive upon redemption a
price per share lower than the shareholder's original cost.

TAXES

FEDERAL TAXATION

The policy of the Portfolio is to distribute to its shareholders at least
90% of its investment company taxable income for each year and consistent
therewith to meet the distribution requirements of Part I of Subchapter M of the
Internal Revenue Code of 1986, as amended (the "Code"). The Portfolio intends to
distribute at least 98% of its net investment income for the calendar year and
at least 98% of its net realized capital gains, if any, for the one-year period
ending on October 31 and therefore to meet the distribution requirements imposed
by the Code in order to avoid the imposition of a 4% excise tax. The Portfolio
also intends to meet the other requirements of Subchapter M, including the
requirements with respect to diversification of assets and sources of income, so
that the Portfolio will pay no federal income taxes on net investment income and
net realized capital gains paid to shareholders.

The Portfolio will be treated as a separate corporation for purposes of
determining taxable income, distribution requirements and other requirements of
Subchapter M. Therefore, the Portfolio may not offset its gains against losses
of the other portfolios of the Trust and each portfolio of the Trust must
specifically comply with all the provisions of the Code.

Dividends paid by the Portfolio are subject to taxation as of the date of
payment, whether received by shareholders in cash or shares of the Portfolio.
The Code provides an exception to this general rule: if the Portfolio declares a
dividend in October, November or December to shareholders of record in such
months and pays the dividend during January of the next year, a shareholder will
be treated for tax purposes as having received the dividend on December 31 of
the year in which it is declared rather than in January of the following year
when it is paid. It is anticipated that no portion of distributions will be
eligible for the dividends received deduction for corporations. Dividends paid
by the Portfolio from its net investment income and short-term capital gains are
taxable to shareholders at ordinary income tax rates.

Foreign persons who file a United States tax return after December 31, 1996
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 the
Transfer Agent.

STATE AND LOCAL TAXATION

Distributions and other Trust transactions referred to in the preceding
paragraphs may be subject to state, local or foreign taxes, and the treatment
thereof may differ from the federal income tax consequences discussed herein.
The Portfolio's investment strategy is intended to provide shareholders with
dividends that are exempt from state and local personal and, in some cases,
corporate income taxation in as many jurisdictions as possible. The possible
exemption from such taxation may enable shareholders to achieve an after-tax
return comparable to or higher than that obtained from other money market funds.
Shareholders

10
<PAGE> 11

should consult their own tax advisors concerning the tax impact of their
investment in the Portfolio and the application of state, local or foreign
taxes.

NET ASSET VALUE

The net asset value per share of the Portfolio is determined daily as of
3:00 p.m. Eastern Time on each business day of the Portfolio. Net asset value
per share is determined by dividing the value of the Portfolio's securities,
cash and other assets (including interest accrued but not collected) less all of
its liabilities (including accrued expenses and dividends payable), by the
number of shares outstanding of the Portfolio and rounding the resulting per
share net asset value to the nearest one cent.

The securities of the Portfolio are valued on the basis of amortized cost
pursuant to rules promulgated by the SEC applicable to money market funds. 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,
regardless of the impact of fluctuating interest rates on the market value of
the security. 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 Portfolio would receive if the security were sold.
During such periods, the daily yield on shares of the Portfolio, computed as
described in "Purchases and Redemptions -- Performance Information" in the
Statement of Additional Information, may differ somewhat from an identical
computation made by an investment company with identical investments utilizing
available indications as to market value to value its portfolio securities.

YIELD INFORMATION

Yield information for the Class can be obtained by calling the Trust at
(800) 877-7745. Yields will fluctuate from time to time and are not necessarily
indicative of future results. Accordingly, the yield information may not provide
a basis for comparison with investments which pay a fixed rate of interest for a
stated period of time. Yield is a function of the type and quality of the
Portfolio's investments, the Portfolio's maturity and the operating expense
ratio of the Class. A SHAREHOLDER'S INVESTMENT IN THE PORTFOLIO IS NOT INSURED
OR GUARANTEED BY THE U.S. GOVERNMENT OR BY ANY INSTITUTION. These factors should
be carefully considered by the investor before making an investment in the
Portfolio.

To assist banks and other institutions performing their own sub-accounting,
same day information as to the daily dividend per share for the Portfolio to
eight decimal places and current yield normally will be available by 4:00 p.m.
Eastern Time.

From time to time and in its discretion, AIM or its affiliates may waive
all or a portion of its advisory fees and/or assume certain expenses of the
Portfolio. Such a practice will have the effect of increasing the Portfolio's
yield and total return.

REPORTS TO SHAREHOLDERS

Unless otherwise requested by the shareholder, each shareholder will be
provided with a written confirmation for each transaction by its Institution.
Institutions establishing sub-accounts will receive a written confirmation for
each transaction in a sub-account. Duplicate confirmations may be transmitted to
the beneficial owner of the sub-account if requested by the Institution. The
Institution will receive a periodic statement setting forth, for each
sub-account, the share balance, income earned for the month, income earned for
the year to date and the total current value of the account.

11
<PAGE> 12

MANAGEMENT OF THE TRUST

BOARD OF TRUSTEES

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 AIM, subject always to the objectives
and policies of the Trust and to the general supervision of the Trust's Board of
Trustees. Information concerning the Board of Trustees may be found in the
Statement of Additional Information. 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.

For a discussion of AIM Management and its subsidiaries' Year 2000
Compliance Project, see "General Information -- Year 2000 Compliance Project."

INVESTMENT ADVISOR

A I M Advisors, Inc., 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173, acts as the investment advisor for the Portfolio pursuant to a
Master Investment Advisory Agreement (the "Advisory Agreement"). AIM was
organized in 1976 and, together with its affiliates, manages or advises over 90
investment company portfolios. Certain of the directors and officers of AIM are
also trustees or executive officers of the Trust. AIM is a wholly owned
subsidiary of AIM Management. AIM Management is a holding company in the
financial services business. AIM Management is an indirect, wholly owned
subsidiary of AMVESCAP PLC, a publicly-traded holding company that, through its
subsidiaries, engages in institutional investment management and retail fund
businesses in the United States, Europe and the Pacific Region.

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. The Advisory Agreement requires AIM to reduce its fee to the extent
required to satisfy any expense limitations imposed by the securities laws or
regulations thereunder of any state in which the Portfolio's shares are
qualified for sale.

ADMINISTRATIVE SERVICES

The Trust has entered into a Master Administrative Services Agreement with
AIM (the "Administrative Services Agreement"), pursuant to which AIM has agreed
to provide or arrange for the provision of certain accounting and other
administrative services to the Portfolio, including the services of a principal
financial officer of the Trust and related staff. As compensation to AIM for its
services under the Administrative Services Agreement, the Portfolio may
reimburse AIM for expenses incurred by AIM in connection with such services.

FEE WAIVERS

AIM or its affiliates may in its discretion from time to time agree to
waive voluntarily all or any portion of its advisory fee and/or assume certain
expenses of the Portfolio but will retain its ability to be reimbursed for such
fee or expenses prior to the end of each fiscal year. AIM voluntarily waived
advisory fees of $167,622 on the Portfolio during the year ended August 31,
1998.

DISTRIBUTOR

12
<PAGE> 13

the shares of the Class. The address of FMC is 11 Greenway Plaza, Suite 100,
Houston, Texas 77046-1173. Certain trustees and officers of the Trust are
affiliated with FMC and AIM. The Distribution Agreement provides that FMC has
the exclusive right to distribute shares of the Class either directly or through
other broker-dealers. FMC is the distributor of several of the mutual funds
managed or advised by AIM.

FMC may, from time to time, at its expense, pay a bonus or other
consideration or incentive to dealers or banks who sell a minimum dollar amount
of the shares of the 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 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 of the Class 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. The Plan provides that the Trust may compensate
FMC in connection with the distribution of shares of the Class in an amount
equal to 0.10% on an annualized basis of the average daily net assets of the
Portfolio attributable to the Class. Such amounts may be expended when and if
authorized by the Board of Trustees and may be used to finance such
distribution-related services 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
costs of administering the Plan.

Of the compensation paid to FMC under the Plan, a service fee may be paid
to dealers and other financial institutions that provide continuing personal
shareholder services to their customers who purchase and own shares of the
Class, in amounts of up to 0.10% of the average net assets of the Portfolio
attributable to the Class which are attributable to the customers of such
dealers or financial institutions. Payments retained by FMC would be
characterized as an asset-based sales charge pursuant to the 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 the Class. The Plan
does not obligate the Trust to reimburse FMC for the actual expenses FMC may
incur in fulfilling its obligations under the Plan on behalf of the Class. Thus,
under the Plan, 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.

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 each 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.

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 will
benefit the Trust and the shareholders of the Class.

The Plan may be terminated by a vote of a majority of the Qualified
Trustees, or by a vote of a majority of the holders of the outstanding voting
securities of the shares of the Class. Any change in the Plan that would
increase materially the distribution expenses paid by the 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.

13
<PAGE> 14

PORTFOLIO TRANSACTIONS AND BROKERAGE

AIM is responsible for decisions to buy and sell securities for the
Portfolio, broker-dealer selection and negotiation of commission rates. Since
purchases and sales of portfolio securities by the Portfolio are usually
principal transactions, the Portfolio incurs little or no brokerage commissions.
Portfolio securities are normally purchased directly from the issuer or from a
market maker for the securities. The purchase price paid to dealers serving as
market makers may include a spread between the bid and asked prices.

AIM's primary consideration in effecting a security transaction is to
obtain the best net price and the most favorable execution of the order. To the
extent that the executions and prices offered by more than one dealer are
comparable, AIM may, in its discretion, effect transactions with dealers that
furnish statistical, research or other information or services which are deemed
by AIM to be beneficial to the Portfolio's investment programs. Certain research
services furnished by dealers may be useful to clients of AIM other than the
Portfolio. Similarly, any research services received by AIM through placement of
portfolio transactions of other clients may be of value to AIM in fulfilling its
obligations to the Portfolio.

GENERAL INFORMATION

ORGANIZATION AND DESCRIPTION OF SHARES

The Trust is a Delaware business trust. The Trust was originally
incorporated in Maryland on January 24, 1977, but had no operations prior to
November 10, 1980. Effective December 31, 1986, the Trust was reorganized as a
Massachusetts business trust; and effective October 15, 1993, the Trust was
reorganized as a Delaware business trust. On October 15, 1993, the Portfolio
succeeded to the assets and assumed the liabilities of the Treasury TaxAdvantage
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 Prospectus 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 divided into eighteen classes. Six classes, including the Class,
represent interests in the Portfolio, six classes represent interests in the
Government & Agency Portfolio and six classes represent interests in the
Treasury Portfolio. Each class of shares has a par value of $.01 per share. The
other classes of the Trust may have different sales charges and other expenses
which may affect performance. An investor may obtain information concerning the
Trust's other classes by contacting FMC.

All shares of the Trust have equal rights with respect to voting, except
that the holders of shares of a particular portfolio or class will have the
exclusive right to vote on matters pertaining solely to that portfolio or class.
For example, holders of shares of a particular portfolio will have the exclusive
right to vote on any investment advisory agreement or investment restriction
that relates only to such portfolio. In addition, if a portfolio is divided into
various classes, holders of shares of a particular class will have the exclusive
right to vote on any matter, such as distribution arrangements, which relates
solely to such class. The shareholders of the Class have distinctive rights with
respect to dividends and redemption which are more fully described in this
Prospectus. In the event of liquidation or termination of the Trust, holders of
shares of each portfolio will receive pro rata, subject to the rights of
creditors, (a) the proceeds of the sale of the assets held in the respective
portfolio to which such shares relate, less (b) the liabilities of the Trust
attributable to the respective portfolio or allocated to the respective
portfolio based on the liquidation value of such portfolio. Fractional shares of
each portfolio have the same rights as full shares to the extent of their
proportionate interest.

There will not normally be annual shareholders' meetings. Shareholders may
remove trustees from office by votes cast at a meeting of shareholders called
solely for such purpose or by written consent. A meeting of shareholders for the
sole purpose of considering removal of a trustee shall be called at the request
of the holders of 10% or more of the Trust's outstanding shares.

14
<PAGE> 15

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. The Board of Trustees may create additional portfolios and
classes of the Trust without shareholder approval.

TRANSFER AGENT AND CUSTODIAN

The Bank of New York, 90 Washington Street, 11th Floor, New York, New York
10286, acts as custodian for the portfolio securities and cash of the Portfolio.
A I M Fund Services, Inc., P.O. Box 4497, Houston, TX 77210-4497, acts as
transfer agent for the shares of the Portfolio.

LEGAL COUNSEL

The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania, serves as counsel to the Trust and passes upon certain legal
matters for the Trust.

SHAREHOLDER INQUIRIES

Shareholder inquiries concerning the status of an account should be
directed to an investor's Institution, or to the Trust at 11 Greenway Plaza,
Suite 100, Houston, Texas 77046-1173, or may be made by calling (800) 877-7745.

YEAR 2000 COMPLIANCE PROJECT

In providing services to the Trust, AIM Management and its subsidiaries
rely on both internal software systems as well as external software systems
provided by third parties. Many software systems in use today are unable to
distinguish the year 2000 from the year 1900. This defect if not cured will
likely adversely affect the services that AIM Management, its subsidiaries and
other service providers to the Trust provide the Trust and its shareholders.

To address this issue, AIM Management and its subsidiaries, together with
independent technology consultants, are undertaking a comprehensive Year 2000
Compliance Project (the "Project"). The Project consists of three phases, namely
(i) inventorying every software application in use at AIM Management and its
subsidiaries, as well as remote, third party software systems on which AIM
Management and its subsidiaries rely, (ii) identifying those applications that
may not function properly after December 31, 1999, and (iii) correcting and
subsequently testing those applications that may not function properly after
December 31, 1999. Phases (i) and (ii) are complete and phase (iii) has
commenced. The Project is scheduled to be completed during the second quarter of
1999. Software applications acquired by AIM Management and its subsidiaries
after completion of the Project will be reviewed to confirm year 2000 compliance
upon installation. No assurance can be given that the Project will be successful
or that AIM Management and its subsidiaries will not otherwise be adversely
affected by the year 2000 issue.

OTHER INFORMATION

This Prospectus sets forth basic information that investors should know
about the Trust and the Portfolio prior to investing. A Statement of Additional
Information has been filed with the SEC. Copies of the Statement of Additional
Information are available upon request and without charge by writing or calling
the Trust or FMC. This Prospectus omits certain information contained in the
registration statement filed with the SEC. Copies of the registration statement,
including items omitted herein, may be obtained from the SEC by paying the
charges prescribed under its rules and regulations.

15
<PAGE> 16
================================================================================

SHORT-TERM INVESTMENTS TRUST
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-7745

INVESTMENT ADVISOR
A I M ADVISORS, INC.
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(713) 626-1919

DISTRIBUTOR
FUND MANAGEMENT COMPANY
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-7745

AUDITORS
KPMG PEAT MARWICK LLP
700 Louisiana
Houston, Texas 77002

CUSTODIAN
THE BANK OF NEW YORK
90 Washington Street
11th Floor
New York, New York 10286

TRANSFER AGENT
A I M FUND SERVICES, INC.
P.O. Box 4497
Houston, Texas 77210-4497

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATIONS
NOT CONTAINED IN THIS PROSPECTUS IN
CONNECTION WITH THE OFFERING MADE BY THIS
PROSPECTUS, AND IF GIVEN OR MADE, SUCH
INFORMATION OR REPRESENTATIONS MUST NOT BE
RELIED UPON AS HAVING BEEN AUTHORIZED BY THE
TRUST OR THE DISTRIBUTOR. THIS PROSPECTUS DOES
NOT CONSTITUTE AN OFFER IN ANY JURISDICTION
TO ANY PERSON TO WHOM SUCH OFFERING MAY NOT
LAWFULLY BE MADE.
================================================================================

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

PROSPECTUS

December 18, 1998

SHORT-TERM
INVESTMENTS TRUST

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

TREASURY
TAXADVANTAGE
PORTFOLIO

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

CASH MANAGEMENT CLASS
TABLE OF CONTENTS

<TABLE>
<CAPTION>
PAGE
<S> <C>
Summary........................................... 2
Table of Fees and Expenses........................ 4
Suitability for Investors......................... 5
Investment Program................................ 5
Purchase of Shares................................ 7
Redemption of Shares.............................. 8
Dividends......................................... 9
Taxes............................................. 10
Net Asset Value................................... 11
Yield Information................................. 11
Reports to Shareholders........................... 11
Management of the Trust........................... 12
General Information............................... 14
</TABLE>
================================================================================
<PAGE> 17
SHORT-TERM
INVESTMENTS TRUST

Prospectus
- --------------------------------------------------------------------------------

TREASURY The Treasury TaxAdvantage Portfolio is a money
TAXADVANTAGE market fund whose investment objective is the
PORTFOLIO maximization of current income to the extent consistent
with the preservation of capital and the maintenance of
INSTITUTIONAL liquidity. The Treasury TaxAdvantage Portfolio seeks to
CLASS achieve its objective by investing in direct
obligations of the U.S. Treasury. The Treasury
TaxAdvantage Portfolio's investment strategy is
DECEMBER 18, 1998 intended to enable the Portfolio to provide its
shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions. The
instruments purchased by the Treasury TaxAdvantage
Portfolio will have maturities of 397 days or less.
The Treasury TaxAdvantage Portfolio is a series
portfolio of Short-Term Investments Trust (the
"Trust"), an open-end diversified series management
investment company. This prospectus relates solely to
the Institutional Class of the Treasury TaxAdvantage
Portfolio, a class of shares designed to be a
convenient vehicle in which institutions, particularly
banks, acting for themselves or in a fiduciary,
advisory, agency, custodial or other similar capacity,
can invest short-term cash reserves.
THESE SECURITIES HAVE NOT BEEN APPROVED OR
DISAPPROVED BY THE SECURITIES AND EXCHANGE COMMISSION
NOR HAS THE SECURITIES AND EXCHANGE COMMISSION PASSED
UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

THIS PROSPECTUS SETS FORTH BASIC INFORMATION THAT
A PROSPECTIVE INVESTOR SHOULD KNOW BEFORE INVESTING IN
SHARES OF THE TREASURY TAXADVANTAGE PORTFOLIO AND
SHOULD BE READ AND RETAINED FOR FUTURE REFERENCE. A
STATEMENT OF ADDITIONAL INFORMATION, DATED DECEMBER 18,
1998, HAS BEEN FILED WITH THE UNITED STATES SECURITIES
AND EXCHANGE COMMISSION (THE "SEC") AND IS HEREBY
INCORPORATED BY REFERENCE. A COPY OF THE STATEMENT OF
ADDITIONAL INFORMATION IS ATTACHED HERETO. THE SEC
MAINTAINS A WEB SITE AT HTTP://WWW.SEC.GOV THAT
CONTAINS THE STATEMENT OF ADDITIONAL INFORMATION,
MATERIAL INCORPORATED BY REFERENCE, AND OTHER
INFORMATION REGARDING THE TRUST.

[AIM LOGO APPEARS HERE]
Fund Management Company

11 Greenway Plaza
Suite 100
Houston, Texas 77046-1173
(800) 659-1005
<PAGE> 18

SUMMARY

THE PORTFOLIO AND ITS INVESTMENT OBJECTIVE

The Trust is an open-end diversified series management investment company.
Pursuant to this Prospectus, the Trust offers shares of the Institutional Class
(the "Class") of the Treasury TaxAdvantage Portfolio (the "Portfolio") without a
sales charge. The investment objective of the Portfolio is the maximization of
current income to the extent consistent with the preservation of capital and the
maintenance of liquidity. To achieve its objective, the Portfolio will invest in
direct obligations of the U.S. Treasury. The instruments purchased by the
Portfolio will have maturities of 397 days or less. The Portfolio's investment
strategy is intended to enable the Portfolio to provide its shareholders with
dividends that are exempt from state and local income taxation in certain
jurisdictions.

Pursuant to separate prospectuses, the Trust offers other classes of shares of
beneficial interest representing interests in the Portfolio: the Cash Management
Class, the Personal Investment Class, the Private Investment Class, the Reserve
Class and the Resource Class. Such classes have different distribution
arrangements and are designed for different categories of investors. The Trust
also offers shares of several classes of the Trust representing interests in
each of two other portfolios, the Government & Agency Portfolio and the Treasury
Portfolio. The portfolios of the Trust are referred to collectively as the
"Portfolios."

Because the Trust declares dividends on a daily basis, shares of each class of
the Portfolio have the same net asset value (proportionate interest in the net
assets of the Portfolio) and bear equally those expenses, such as the advisory
fee, that are allocated to the Portfolio as a whole. All classes of the
Portfolio share a common investment objective and portfolio of investments.
However, different classes of the Portfolio have different shareholder
qualifications and are separately allocated certain class expenses, such as
those associated with the distribution of their shares. Therefore, each class
will have a different dividend payment and a different yield.

INVESTORS IN THE CLASS

The Class is designed to be a convenient and economical investment vehicle in
which institutions, particularly banks, acting for themselves or in a fiduciary,
advisory, agency, custodial or other similar capacity, can invest short-term
cash reserves. Although shares of the Class may not be purchased by individuals
directly, institutions may purchase shares for accounts maintained by
individuals. See "Suitability for Investors." Although there is no sales charge
imposed on the purchase of shares of the Class, banks or other institutions may
charge a recordkeeping, account maintenance or other fee to their customers and
beneficial holders of the shares of the Class should consult with the
institutions maintaining their accounts to obtain a schedule of applicable fees.

PURCHASE OF SHARES

The shares of the Class are sold at net asset value, without a sales charge.
The minimum initial investment in the Class is $1,000,000. There is no minimum
amount for subsequent investments. Payment for shares of the Class purchased
must be in federal funds or other funds immediately available to the Portfolio.
See "Purchase of Shares."

REDEMPTION OF SHARES

DIVIDENDS

The net income of the Portfolio is declared as a dividend daily to
shareholders of record immediately after 3:00 p.m. Eastern Time. Dividends are
paid monthly by check or wire transfer unless a shareholder has previously
elected to have such dividends automatically reinvested in additional shares of
the Class. Information concerning the amount of the dividends declared on any
particular day will normally be available by 4:00 p.m. Eastern Time on that day.
See "Dividends."

NET ASSET VALUE

The Trust uses the amortized cost method of valuing its securities held by the
Portfolio and rounds the per share net asset value to the nearest whole cent.
Accordingly, the net asset value per share of the Portfolio will normally remain
constant at

2
<PAGE> 19

$1.00. AN INVESTMENT IN THE PORTFOLIO IS NOT INSURED OR GUARANTEED BY THE U.S.
GOVERNMENT, AND THERE IS NO ASSURANCE THAT THE PORTFOLIO WILL BE ABLE TO
MAINTAIN A STABLE NET ASSET VALUE. SEE "NET ASSET VALUE."

INVESTMENT ADVISOR

A I M Advisors, Inc. ("AIM") serves as the Portfolio's investment advisor and
receives a fee based on the Portfolio's average daily net assets pursuant to a
master investment advisory agreement. For its services, AIM receives a fee based
on the average daily net assets of the Portfolio. During the fiscal year ended
August 31, 1998, the Trust paid AIM fees with respect to the Portfolio which
represented 0.12% of the average net assets of the Portfolio. AIM is primarily
engaged in the business of acting as manager or advisor to investment companies.
See "Management of the Trust -- Investment Advisor." Under a separate
administrative services agreement with the Trust, AIM may receive reimbursement
of its costs to perform certain accounting and other administrative services for
the Portfolio. See "Management of the Trust -- Investment Advisor" and
"-- Administrative Services." Under a Transfer Agency and Service Agreement,
A I M Fund Services, Inc. ("Transfer Agent"), AIM's wholly owned subsidiary and
a registered transfer agent, receives a fee for its provision of transfer
agency, dividend distribution and disbursement, and shareholder services to the
Trust. See "General Information -- Transfer Agent and Custodian."

DISTRIBUTOR

Fund Management Company ("FMC") acts as the exclusive distributor of the
shares of the Class. FMC does not receive any fee for distribution services from
the Trust. See "Purchase of Shares."

SPECIAL RISK CONSIDERATIONS

3
<PAGE> 20

TABLE OF FEES AND EXPENSES

<TABLE>
<S> <C> <C>
SHAREHOLDER TRANSACTION EXPENSES*
Maximum sales load imposed on purchases
(as a percentage of offering price).................... None
Maximum sales load on reinvested dividends
(as a percentage of offering price).................... None
Deferred sales load (as a percentage of original
purchase price or redemption proceeds, as
applicable)............................................ None
Redemption fees (as a percentage of amount
redeemed, if applicable)............................... None
Exchange fee.............................................. None
ANNUAL PORTFOLIO OPERATING EXPENSES -- INSTITUTIONAL CLASS
(AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management fees**......................................... 0.12%
12b-1 fees................................................ None
Other expenses:
Custodian fees......................................... 0.01%
Other.................................................. 0.07%
-----
Total other expenses................................. 0.08%
----
Total portfolio operating expenses -- Institutional
Class**................................................ 0.20%
====
</TABLE>

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

* Beneficial owners of shares of the Class should consider the effect of any
charges imposed by their bank or other financial institution for various
services.

** Had there been no fee waivers, Management fees and Total portfolio operating
expenses would be 0.20% and 0.28%, respectively.

EXAMPLE

An investor would pay the following expenses on a $1,000 investment, assuming
(1) a 5% annual return and (2) redemption at the end of each time period.

<TABLE>
<S> <C>
1 year..................................................... $ 2
3 years.................................................... $ 6
5 years.................................................... $11
10 years.................................................... $26
</TABLE>

The Table of Fees and Expenses is designed to assist an investor in
understanding the various costs and expenses that an investor in the Class will
bear directly or indirectly. For more complete descriptions of the various costs
and expenses, see "Management of the Trust" below. The expense figures are based
upon actual costs and fees charged to the Class for the fiscal year ended August
31, 1998. Future waivers of fees (if any) may vary from the figures reflected in
the Table of Fees and Expenses. To the extent any service providers assume
expenses of the Class, such assumption of expenses will have the effect of
lowering the Class's overall expense ratio and increasing its yield to
investors. Beneficial owners of shares of the Class should also consider the
effect of any charges imposed by the institution maintaining their accounts.

The example in the Table of Fees and Expenses assumes that all dividends and
distributions are reinvested and that the amounts listed under "Annual Portfolio
Operating Expenses -- Institutional Class" remain the same in the years shown.

4
<PAGE> 21

FINANCIAL HIGHLIGHTS

Shown below are the per share ratios and supplemental data (collectively
"data") for the years in the eight-year period
ended August 31, 1998 and the period August 17, 1990 (date sales commenced)
through August 31, 1990. The data has been audited by KPMG Peat Marwick LLP,
independent auditors, whose report on the financial statements and the related
notes appears in the Statement of Additional Information.
<TABLE>
<CAPTION>
AUGUST 31,
---------------------------------------------------------------------------------
1998 1997 1996 1995 1994 1993 1992
-------- -------- -------- -------- -------- -------- --------
<S> <C> <C> <C> <C> <C> <C> <C>
Net asset value,
beginning of period.... $ 1.00 $ 1.00 $ 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 0.03 0.03 0.04
-------- -------- -------- -------- -------- -------- --------
Less distributions:
Dividends from net
investment income.... (0.05) (0.05) (0.05) (0.05) (0.03) (0.03) (0.04)
-------- -------- -------- -------- -------- -------- --------
Net asset value, end of
period................. $ 1.00 $ 1.00 $ 1.00 $ 1.00 $ 1.00 $ 1.00 $ 1.00
======== ======== ======== ======== ======== ======== ========
Total return............. 5.30% 5.13% 5.19% 5.35% 3.29% 2.96% 4.32%
======== ======== ======== ======== ======== ======== ========
Ratios/supplemental data:
Net assets, end of
period (000s
omitted)............. $113,084 $258,251 $407,218 $394,376 $403,882 $434,693 $573,283
======== ======== ======== ======== ======== ======== ========
Ratio of expenses to
average net
assets(b)............ 0.20%(c) 0.20% 0.20% 0.20% 0.20% 0.20% 0.17%
======== ======== ======== ======== ======== ======== ========
Ratio of net investment
income to average net
assets(d)............ 5.05%(c) 5.00% 5.06% 5.21% 3.23% 2.93% 4.16%
======== ======== ======== ======== ======== ======== ========

<CAPTION>
AUGUST 31,
--------------------
1991 1990
-------- --------
<S> <C> <C>
Net asset value,
beginning of period.... $ 1.00 $ 1.00
Income from investment
operations:
Net investment
income............... 0.07 0.003
-------- --------
Less distributions:
Dividends from net
investment income.... (0.07) (0.003)
-------- --------
Net asset value, end of
period................. $ 1.00 $ 1.00
======== ========
Total return............. 6.70% 7.79%(a)
======== ========
Ratios/supplemental data:
Net assets, end of
period (000s
omitted)............. $403,846 $ 16,201
======== ========
Ratio of expenses to
average net
assets(b)............ 0.14% 0.10%(a)
======== ========
Ratio of net investment
income to average net
assets(d)............ 6.16% 7.74%(a)
======== ========
</TABLE>

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

(a) Annualized.

(b) After fee waivers and/or expense reimbursements. Ratios of expenses to
average net assets prior to waiver of advisory fees were 0.28%, 0.23%,
0.23%, 0.23% and 0.23% for the periods 1998-1994, respectively, and 0.21%,
0.25% and 1.24% (annualized) for the periods 1992-1990, respectively.

(d) Ratios of net investment income to average net assets prior to waiver of
advisory fees were 4.97%, 4.97%, 5.04%, 5.18% and 3.20% for the periods
1998-1994, respectively, and 4.13%, 6.04% and 6.60% (annualized) for the
periods 1992-1990, respectively.

5
<PAGE> 22

SUITABILITY FOR INVESTORS

The Class is intended for use primarily by institutions, particularly banks,
acting for themselves or in a fiduciary, advisory, agency, custodial or other
similar capacity. It is designed to be a convenient and economical vehicle in
which such institutions can invest short-term cash reserves. The Portfolio's
investment strategy is intended to provide its shareholders with dividends that
are exempt from state and local income taxation in certain jurisdictions. Shares
of the Class may not be purchased directly by individuals, although institutions
may purchase shares for accounts maintained by individuals. Prospective
investors should determine if an investment in the Class is consistent with the
objectives of an account and with applicable state and federal laws and
regulations.

An investment in the Class may relieve the institution of many of the
investment and administrative burdens encountered when investing in money market
instruments directly. These include: selection of portfolio investments;
surveying the market for the best price at which to buy and sell; valuation of
portfolio securities; selection and scheduling of maturities; receipt, delivery
and safekeeping of securities; and portfolio record keeping. It is anticipated
that most institutions will perform their own subaccounting. To assist these
institutions, information concerning the dividends declared by the Portfolio on
any particular day will normally be available by 4:00 p.m. Eastern Time on that
day.

Investors in the 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 same-day liquidity. Although there is no sales charge
imposed on the purchase of shares of the Class, banks or other institutions may
charge a record keeping, account maintenance or other fee to their customers,
and beneficial holders of the shares of the Class should consult with the
institutions maintaining their accounts to obtain a schedule of applicable fees.
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
Class. However, these expenses are expected to be relatively small due primarily
to the following factors: the Class will have a small number of shareholders who
do not need many of the services provided by other money market investment
companies, thereby resulting in lower transfer agent fees and costs for printing
reports and proxy statements; sales of the Class's shares to institutions acting
for themselves or in a fiduciary capacity are exempt from the registration
requirements of most state securities laws, thereby resulting in reduced state
registration fees; and the relatively low investment advisory fee paid to AIM.

INVESTMENT PROGRAM

INVESTMENT OBJECTIVE

The investment objective of the Portfolio is the maximization of current
income to the extent consistent with the preservation of capital and the
maintenance of liquidity. The Portfolio intends to provide its shareholders with
dividends that are exempt from state and local income taxation in certain
jurisdictions. The Portfolio seeks to achieve its objective by investing in
direct obligations of the U. S. Treasury. The obligations in which the Portfolio
invests are considered to carry very little risk and accordingly may not have as
high a yield as that available on instruments of lesser quality.

INVESTMENT POLICIES

The Portfolio invests exclusively in direct obligations of the U.S. Treasury,
which include Treasury bills, notes and bonds. The market values of the money
market instruments held by the Portfolio will be affected by changes in the
yields available on similar securities. If yields have increased since a
security was purchased, the market value of such security will generally have
decreased. Conversely, if yields have decreased, the market value of such
security will generally have increased.

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. The Portfolio will
only borrow money or enter into reverse repurchase agreements for temporary or
emergency purposes, such as to facilitate the orderly sale of portfolio
securities to accommodate abnormally heavy redemption requests should they
occur. Borrowing will not be made for leverage purposes. 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. Reverse repurchase agreements involve the risk that

6
<PAGE> 23

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 under the 1940 Act.

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 market. 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. 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. 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, however, the high turnover rate should not adversely affect the
Portfolio's net income.

INVESTMENT IN OTHER INVESTMENT COMPANIES. The Trust is permitted to invest in
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 investment policies described above may be changed by the Board of
Trustees without the affirmative vote of a majority of the outstanding shares of
beneficial interest of the Trust.

INVESTMENT RESTRICTIONS

7
<PAGE> 24

PURCHASE OF SHARES

Shares of the Class are sold on a continuous basis at their net asset value
next determined after an order has been received by the Portfolio. As discussed
below, the Trust reserves the right to reject any purchase order. Although there
is no sales charge imposed on the purchase of shares of the Class, banks or
other institutions may charge a recordkeeping, account maintenance or other fee
to their customers, and beneficial holders of the shares of the Class should
consult with the institutions maintaining their accounts to obtain a schedule of
applicable fees. To facilitate the investment of proceeds of purchase orders,
investors are urged to place their orders as early in the day as possible.
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 3:00 p.m. Eastern Time on a business day of the Portfolio. Purchase
orders received after such time will be processed at the next day's net asset
value. Following the initial investment, subsequent purchases of shares of the
Class may also be made via AIM LINK(R) Remote, a personal computer application
software product. Shares of the Class will earn the dividend declared on the
effective date of purchase.

A "business day of the Portfolio" is any day on which both the Federal Reserve
Bank of New York and The Bank of New York, the Trust's custodian, are open for
business. The Portfolio, however, reserves the right to change the time for
which purchase and redemption requests must be submitted to the Portfolio for
execution on the same day or any day when the U.S. primary broker-dealer
community is closed for business or trading is restricted due to national
holidays. It is expected that The Bank of New York and the Federal Reserve Bank
of New York will be closed during the next twelve months on Saturdays and
Sundays, and on the observed holidays of New Year's Day, Martin Luther King,
Jr.'s Birthday, Presidents' Day, Memorial Day, Independence Day, Labor Day,
Columbus Day, Veterans' Day, Thanksgiving Day and Christmas Day.

Subject to the conditions stated above and the Trust's right to reject any
purchase order, orders will be accepted (i) when payment for shares of the Class
purchased is received by The Bank of New York, the Trust's custodian bank, in
the form described below and notice of such order is provided to the Transfer
Agent or (ii) at the time the order is placed, if the Trust is assured of
payment. Shares of the Class purchased by orders which are accepted prior to
3:00 p.m. Eastern Time will earn the dividend declared on the date of purchase.

Any request for a correction to a transaction of Portfolio shares must be
submitted in writing to the Transfer Agent. The Transfer Agent 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.

Payments for shares purchased must be in the form of federal funds or other
funds immediately available to the Portfolio. Federal Reserve wires should be
sent as early as possible in order to facilitate crediting to the shareholder's
account. Any funds received with respect to an order which is not accepted by
the Portfolio and any funds received for which an order has not been received
will be returned to the sending institution.

The minimum initial investment in the Class is $1,000,000. Institutions may be
requested to maintain separate Master Accounts in the Class for shares held by
the institution (i) for its own account, for the account of other institutions
and for accounts for which the institution acts as a fiduciary, and (ii) for
accounts for which the institution acts in some other capacity. An institution's
Master Account(s) and sub-accounts with the Class may be aggregated for the
purpose of the minimum investment requirement. No minimum amount is required for
subsequent investments in the Class nor are minimum balances required. Prior to
the initial purchase of shares of the Class, an Account Application must be
completed and sent to the Transfer Agent, P.O. Box 4497, Houston, TX 77210-4497.
Account Applications may be obtained from the Transfer Agent. Any changes made
to the information provided in the Account Application must be made in writing
or by completing a new form and providing it to the Transfer Agent.

The Trust reserves the right in its sole discretion to withdraw all or any
part of the offering made by this Prospectus or to reject any purchase order.

REDEMPTION OF SHARES

A shareholder may redeem any or all of its shares of the Class at the net
asset value next determined after receipt of the redemption request in proper
form by the Trust. Redemption requests with respect to the Class may also be
made via AIM LINK(R) Remote. Normally, the net asset value per share of the
Portfolio will remain constant at $1.00 per share. See "Net Asset Value."
Redemption requests with respect to shares are normally made by calling the
Trust.

Payment for redeemed shares is normally made by Federal Reserve wire to the
commercial bank account designated in the shareholder's Account Application, but
may be remitted by check upon request by a shareholder. If a redemption request
is received by the Transfer Agent prior to 3:00 p.m. Eastern Time on a business
day of the Portfolio, the redemption will be ef-

8
<PAGE> 25

fected at the net asset value next determined on such day and the shares to be
redeemed will not receive the dividend declared on the effective date of the
redemption. If a redemption request is received by the Transfer Agent after 3:00
p.m. Eastern Time or on other than a business day of the Portfolio, the
redemption will be effected at the net asset value of the Portfolio determined
as of 3:00 p.m. Eastern Time on the next business day of the Portfolio, and the
proceeds of such redemption will normally be wired on the effective day of the
redemption. The Portfolio reserves the right to change the time for which
redemption requests must be submitted to and received by the Transfer Agent for
execution on the same day or any day when the U.S. primary broker-dealer
community is closed for business or trading is restricted due to national
holidays.

Shareholders may request a redemption by telephone. Neither the Transfer Agent
nor FMC will be liable for any loss, expense or cost arising out of any
telephone redemption request effected in accordance with the authorization set
forth in the Account Application if they reasonably believe such request to be
genuine but may in certain cases be liable for losses due to unauthorized or
fraudulent transactions if they do not follow reasonable procedures for
verification of telephone transactions. Such reasonable procedures for
verification of telephone transactions may include recordings of telephone
transactions (maintained for six months), and mailings of confirmations promptly
after the transaction.

Payment for shares of the Class redeemed by mail and payment for telephone
redemptions in amounts under $1,000 may be made by check mailed within seven
days after receipt of the redemption request in proper form. The Trust may make
payment for telephone redemptions in excess of $1,000 by check when it is
considered to be in the Portfolio's best interest to do so.

The shares of the Class are not redeemable at the option of the Trust unless
the Board of Trustees of the Trust determines in its sole discretion that
failure to so redeem may have materially adverse consequences to the
shareholders of the Trust.

DIVIDENDS

Dividends from the net income of the Portfolio are declared daily to
shareholders of record of the Class as of immediately after 3:00 p.m. Eastern
Time on the day of declaration. Net income for dividend purposes is determined
daily as of 3:00 p.m. Eastern Time. The dividend accrued and paid for each class
will consist of (a) income of the Portfolio, the allocation of which is based
upon such class's pro rata share of the total outstanding shares representing an
interest in the Portfolio, less (b) Portfolio expenses, such as custodian fees,
trustees' fees and accounting and legal expenses, based upon such class's pro
rata share of the net assets of the Portfolio, less (c) expenses directly
attributable to such class, such as distribution expenses, if any, and transfer
agency fees. Although realized gains and losses on the assets of the Portfolio
are reflected in its net asset value, they are not expected to be of an amount
which would affect the Portfolio's net asset value of $1.00 per share for
purposes of purchases and redemptions. See "Net Asset Value." Distributions from
net realized short-term gains may be declared and paid yearly or more
frequently. See "Taxes." The Portfolio does not expect to realize any long-term
capital gains or losses.

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.
A shareholder may elect to have all dividends automatically reinvested in
additional full and fractional shares of the Portfolio at the net asset value of
such shares as of 3:00 p.m. Eastern Time on the last business day of the month.
Such election, or any revocation thereof, must be made in writing by the
shareholder to the Transfer Agent at P.O. Box 4497, Houston, Texas 77210-4497
and will become effective with dividends paid after its receipt by the Transfer
Agent. If a shareholder redeems all the shares of the Portfolio in its 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.

The Portfolio uses its best efforts to maintain its net asset value per share
of the Portfolio at $1.00 for purposes of sales and redemptions. See "Net Asset
Value." Should the Trust incur or anticipate any unusual expense, loss or
depreciation which could adversely affect the income or net asset value of the
Portfolio, the Trust's 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 the then prevailing circumstances. For example, under such unusual
circumstances the Board of Trustees might reduce or suspend the daily dividend
in order to prevent to the extent possible the net asset value per share of the
Portfolio from being reduced below $1.00. Thus, such expenses, losses or
depreciation may result in a shareholder receiving no dividends for the period
during which it held its Shares and cause such a shareholder to receive upon
redemption a price per share lower than the shareholder's original cost.

9
<PAGE> 26

TAXES

FEDERAL TAXATION

The policy of the Portfolio is to distribute to its shareholders at least 90%
of its investment company taxable income for each year and consistent therewith
to meet the distribution requirements of Part I of Subchapter M of the Internal
Revenue Code of 1986, as amended (the "Code"). The Portfolio intends to
distribute at least 98% of its net investment income for the calendar year and
at least 98% of its net realized capital gains, if any, for the one-year period
ending on October 31 and therefore to meet the distribution requirements imposed
by the Code in order to avoid the imposition of a 4% excise tax. The Portfolio
also intends to meet the other requirements of Subchapter M, including the
requirements with respect to diversification of assets and sources of income, so
that the Portfolio will pay no federal income taxes on net investment income and
net realized capital gains paid to shareholders.

STATE AND LOCAL TAXATION

NET ASSET VALUE

The net asset value per share of the Portfolio is determined daily as of 3:00
p.m. Eastern Time on each business day of the Portfolio. Net asset value per
share is determined by dividing the value of the Portfolio's securities, cash
and other assets (including interest accrued but not collected), less all its
liabilities (including accrued expenses and dividends payable), by the number of
shares outstanding of the Portfolio and rounding the resulting per share net
asset value to the nearest one cent.

YIELD INFORMATION

Yield information for the Class can be obtained by calling the Trust at (800)
659-1005. Yields will fluctuate from time to time and are not necessarily
indicative of future results. Accordingly, the yield information may not provide
a basis for comparison with investments which pay a fixed rate of interest for a
stated period of time. Yield is a function of the type and quality of
10
<PAGE> 27

the Portfolio's investments, the Portfolio's maturity and the operating expense
ratio of the Class. A SHAREHOLDER'S INVESTMENT IN THE TRUST IS NOT INSURED OR
GUARANTEED BY THE U.S. GOVERNMENT OR BY ANY INSTITUTION. These factors should be
carefully considered by the investor before making an investment in the
Portfolio.

For the seven-day period ended August 31, 1998, the current yield and the
effective yield of the Class (which assumes the reinvestment of dividends for a
365-day year and a return for the entire year equal to the average annualized
current yield for the period) were 4.99% and 5.11%, respectively. These
performance numbers are quoted for illustration purposes only. The performance
numbers for any other seven-day period may be substantially different from those
quoted above.

To assist banks and other institutions performing their own sub-accounting,
same day information as to the daily dividend per share for the Class to eight
decimal places and current yield normally will be available by 4:00 p.m. Eastern
Time.

From time to time and in its discretion, AIM or its affiliates may waive all
or a portion of its advisory fees and/or assume certain expenses of the
Portfolio. Such a practice will have the effect of increasing the Portfolio's
yield and total return.

REPORTS TO SHAREHOLDERS

The Trust furnishes shareholders with semi-annual reports containing
information about the Portfolio and its operations, including a list of the
investments held in the Portfolio and financial statements. The annual financial
statements are audited by the Trust's independent certified public accountants.
A copy of the current list of the investments of the Portfolio will be sent to
shareholders upon request.

Unless otherwise requested by the shareholder, each shareholder will be
provided with a written confirmation for each transaction. Institutions
establishing sub-accounts will receive a written confirmation for each
transaction in a sub-account. Duplicate confirmations may be transmitted to the
beneficial owner of the sub-account if requested by the institution. The
institution will receive a periodic statement setting forth, for each
sub-account, the share balance, income earned for the month, income earned for
the year to date and the total current value of the account.

MANAGEMENT OF THE TRUST

BOARD OF TRUSTEES

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 AIM, subject always to the objective and policies of the
Trust and to the general supervision of the Trust's Board of Trustees.
Information concerning the Board of Trustees may be found in the Statement of
Additional Information. 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.

For a discussion of AIM Management and its subsidiaries' Year 2000 Compliance
Project, see "General Information -- Year 2000 Compliance Project."

INVESTMENT ADVISOR

A I M Advisors, Inc., 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173,
acts as the investment advisor for the Portfolio pursuant to a Master Investment
Advisory Agreement (the "Advisory Agreement"). AIM, organized in 1976, together
with its affiliates, manages or advises over 90 investment company portfolios.
Certain of the directors and officers of AIM are also trustees or executive
officers of the Trust. AIM is a wholly owned subsidiary of AIM Management. AIM
Management is a holding company in the financial services business. AIM
Management is an indirect, wholly owned subsidiary of AMVESCAP PLC, a
publicly-traded holding company that, through its subsidiaries, engages in
institutional investment management and retail fund businesses in the United
States, Europe and the Pacific Region.

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. The Advisory Agreement requires AIM to reduce its fee to the extent
required to satisfy any expense limitations imposed by the securities laws or
regulations thereunder of any state in which the Portfolio's shares are
qualified for sale.

For the fiscal year ended August 31, 1998, AIM received fees from the Trust
under the Advisory Agreement with respect to the Portfolio which represented
0.12% of the Portfolio's average daily net assets. During such fiscal year, the
expenses of the Class, including AIM's fees, amounted to 0.20% of the Class's
average daily net assets.

11
<PAGE> 28

ADMINISTRATIVE SERVICES

The Trust has entered into a Master Administrative Services Agreement with AIM
(the "Administrative Services Agreement"), pursuant to which AIM has agreed to
provide or arrange for the provision of certain accounting and other
administrative services to the Portfolio, including the services of a principal
financial officer of the Trust and related staff. As compensation to AIM for its
services under the Administrative Services Agreement the Portfolio may reimburse
AIM for expenses incurred by AIM in connection with such services.

FEE WAIVERS

AIM or its affiliates may in its discretion from time to time agree to waive
voluntarily all or any portion of its advisory fee and/or assume certain
expenses of the Portfolio but will retain its ability to be reimbursed for such
fee or expenses prior to the end of each fiscal year. AIM voluntarily waived
advisory fees of $167,622 on the Portfolio during the year ended August 31,
1998.

DISTRIBUTOR

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 the Portfolio. The
address of FMC is 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173.
Certain trustees and officers of the Trust are affiliated with FMC and AIM. The
Distribution Agreement provides that FMC has the exclusive right to distribute
shares of the Trust either directly or through other broker-dealers. FMC is the
distributor of several of the mutual funds managed or advised by AIM.

FMC may, from time to time, at its expense, pay a bonus or other consideration
or incentive to dealers, banks or other financial institutions who sell a
minimum dollar amount of the shares of the Class during a specific period of
time. In some instances, these incentives may be offered only to certain
dealers, banks or financial institutions who have sold or may sell significant
amounts of shares. The total amount of such additional bonus 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. Sales of the shares of the Class may not be used to
qualify for any incentives to the extent that such incentives may be prohibited
by the laws of any jurisdiction.

PORTFOLIO TRANSACTIONS AND BROKERAGE

AIM is responsible for decisions to buy and sell securities for the Portfolio,
broker-dealer selection and negotiation of commission rates. Since purchases and
sales of portfolio securities by the Portfolio are usually principal
transactions, the Portfolio incurs little or no brokerage commissions. Portfolio
securities are normally purchased directly from the issuer or from a market
maker for the securities. The purchase price paid to dealers serving as market
makers may include a spread between the bid and asked prices.

AIM's primary consideration in effecting a security transaction is to obtain
the best net price and the most favorable execution of the order. To the extent
that the executions and prices offered by more than one dealer are comparable,
AIM may, in its discretion, effect transactions with dealers that furnish
statistical, research or other information or services which are deemed by AIM
to be beneficial to the Portfolio's investment programs. Certain research
services furnished by dealers may be useful to clients of AIM with clients other
than the Portfolio. Similarly, any research services received by AIM through
placement of portfolio transactions of other clients may be of value to AIM in
fulfilling its obligations to the Portfolio.

GENERAL INFORMATION

ORGANIZATION AND DESCRIPTION OF SHARES

The Trust is a Delaware business trust. The Trust was originally incorporated
in Maryland on January 24, 1977, but had no operations prior to November 10,
1980. Effective December 31, 1986, the Trust was reorganized as a Massachusetts
business trust; and effective October 15, 1993, the Trust was reorganized as a
Delaware business trust. On October 15, 1993, the Portfolio succeeded to the
assets and assumed the liabilities of the Treasury TaxAdvantage 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
Prospectus 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 divided into eighteen
classes of which six represent interests in the Government & Agency Portfolio,
six represent interests in the Treasury Portfolio and six represent interests in
the Portfolio. Each class of shares has a par value of $.01 per share. The other
classes of the Trust may have different sales charges and other ex-

12
<PAGE> 29

penses which may affect performance. An investor may obtain information
concerning the Trust's other classes by contacting FMC.

All shares of the Trust have equal rights with respect to voting, except that
the holders of shares of a particular portfolio or class will have the exclusive
right to vote on matters pertaining solely to that portfolio or class. For
example, holders of shares of a particular portfolio will have the exclusive
right to vote on any investment advisory agreement or investment restriction
that relates only to such portfolio. In addition, if a portfolio is divided into
various classes, holders of shares of a particular class will have the exclusive
right to vote on any matter, such as distribution arrangements, which relates
solely to such class. The holders of shares of the Portfolio have distinctive
rights with respect to dividends and redemption which are more fully described
in this Prospectus. In the event of liquidation or termination of the Trust,
holders of shares of each portfolio will receive pro rata, subject to the rights
of creditors, (a) the proceeds of the sale of the assets held in the respective
portfolio to which such shares relate, less (b) the liabilities of the Trust
attributable or allocated to the respective portfolio based on the liquidation
value of the portfolio. Fractional shares of each portfolio have the same rights
as full shares to the extent of their proportionate interest.

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.
The Board of Trustees may create additional portfolios or classes of shares of
the Trust without shareholder approval.

TRANSFER AGENT AND CUSTODIAN

The Bank of New York, 90 Washington Street, 11th Floor, New York, New York
10286, acts as custodian for the portfolio securities and cash of the Portfolio.
A I M Fund Services, Inc., P.O. Box 4497, Houston, TX 77210-4479, acts as
transfer agent for the shares of the Class.

LEGAL COUNSEL

The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania, serves as counsel to the Trust and has passed upon certain legal
matters for the Trust.

SHAREHOLDER INQUIRIES

Shareholder inquiries concerning the status of an account should be directed
to the Trust at 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173, or may
be made by calling (800) 659-1005.

YEAR 2000 COMPLIANCE PROJECT

In providing services to the Trust, AIM Management and its subsidiaries rely
on both internal software systems as well as external software systems provided
by third parties. Many software systems in use today are unable to distinguish
the year 2000 from the year 1900. This defect if not cured will likely adversely
affect the services that AIM Management, its subsidiaries and other service
providers to the Trust provide the Trust and its shareholders.

13
<PAGE> 30

OTHER INFORMATION

This Prospectus sets forth basic information that investors should know about
the Trust and the Portfolio prior to investing. A Statement of Additional
Information has been filed with the SEC. The Statement of Additional Information
is attached as Appendix A to this Prospectus. This Prospectus omits certain
information contained in the registration statement filed with the SEC. Copies
of the registration statement, including items omitted herein, may be obtained
from the SEC by paying the charges prescribed under its rules and regulations.

14
<PAGE> 31

APPENDIX
STATEMENT OF
ADDITIONAL INFORMATION

SHORT-TERM INVESTMENTS TRUST

TREASURY TAXADVANTAGE 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 TAXADVANTAGE 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 18, 1998
RELATING TO THE PROSPECTUS OF EACH OF THE FOLLOWING CLASSES OF THE
TREASURY TAXADVANTAGE PORTFOLIO:
CASH MANAGEMENT CLASS PROSPECTUS DATED DECEMBER 18, 1998,
INSTITUTIONAL CLASS PROSPECTUS DATED DECEMBER 18, 1998,
PERSONAL INVESTMENT CLASS PROSPECTUS DATED DECEMBER 18, 1998,
PRIVATE INVESTMENT CLASS PROSPECTUS DATED DECEMBER 18, 1998,
RESERVE CLASS PROSPECTUS DATED DECEMBER 18, 1998 AND
RESOURCE CLASS PROSPECTUS DATED DECEMBER 18, 1998
A-1
<PAGE> 32

TABLE OF CONTENTS

<TABLE>
<CAPTION>
PAGE
--------
<S> <C>
Introduction................................................ A-3
General Information about the Trust......................... A-3
The Trust and Its Shares............................... A-3
Management.................................................. A-5
Trustees and Officers.................................. A-5
Remuneration of Trustees............................... A-8
Investment Advisor..................................... A-9
Administrative Services................................ A-10
Expenses............................................... A-10
Banking Regulations.................................... A-11
Transfer Agent and Custodian........................... A-11
Reports................................................ A-12
Fee Waivers............................................ A-12
Principal Holders of Securities........................ A-12
Purchases and Redemptions................................... A-15
Net Asset Value Determination.......................... A-16
Distribution Agreement................................. A-16
Distribution Plan...................................... A-16
Performance Information................................ A-17
Investment Program and Restrictions......................... A-17
Investment Program..................................... A-17
Eligible Securities.................................... A-17
Investment Restrictions................................ A-18
Other Investment Policies.............................. A-18
Portfolio Transactions...................................... A-18
General Brokerage Policy............................... A-18
Allocation of Portfolio Transactions................... A-19
Section 28(e) Standards................................ A-19
Tax Matters................................................. A-20
Qualifications as a Regulated Investment Company....... A-20
Excise Tax on Regulated Investment Companies........... A-21
Portfolio Distributions................................ A-21
Sale or Redemption of Shares........................... A-21
Foreign Shareholders................................... A-22
Effect of Future Legislation; State and Local Tax
Considerations........................................ A-22
Financial Statements........................................ FS-1
</TABLE>

A-2
<PAGE> 33

INTRODUCTION

The Treasury TaxAdvantage 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 18, 1998, the Institutional Class Prospectus dated December 18,
1998, the Personal Investment Class Prospectus dated December 18, 1998, the
Private Investment Class Prospectus dated December 18, 1998, the Reserve Class
Prospectus dated December 18, 1998 and the Resource Class Prospectus dated
December 18, 1998 (each a "Prospectus"). Copies of each Prospectus and
additional copies of 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 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 ("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 TaxAdvantage 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 the Prospectus under the captions "General Information" and "Redemption
of 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 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 the shares of each class of the Portfolio. The
Treasury Portfolio and the Government & Agency Portfolio each consists of the
following six classes of shares: Cash Management Class, Institutional Class,
Personal Investment Class, Private Investment Class, Reserve Class and Resource
Class. Shares of the six classes of the Treasury Portfolio and the six classes
of the Government & Agency Portfolio are offered pursuant to separate
prospectuses and separate statements of additional information.

Shares of beneficial interest of the Trust will be 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 the Prospectus under the
caption "Redemption of Shares."

As used in each 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.

A-3
<PAGE> 34

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.

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.

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.
Additional information concerning the rights of share ownership is set forth in
the prospectus applicable to each such class or portfolio of shares of the
Trust.

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 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 or 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 or her 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 or her
official capacity for the Trust, that his or her conduct was in the Trust's best
interests, (2) in all other cases, that his or her conduct was at least not
opposed to the Trust's best interests and (3) in a criminal proceeding, that he
or she had no reason to believe that his or her 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 each 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 the 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 in the Statement of
Additional Information, the trustees shall continue to hold office and may
appoint their successors.

A-4
<PAGE> 35

MANAGEMENT

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 (79) 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
Vice Chairman and Director, AMVESCAP PLC.
- --------------------------------------------------------------------------------------------------------------------------
BRUCE L. CROCKETT (54) 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 (74) 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 (63) Trustee Chairman of the Board of Directors, Mercantile
2 Hopkins Plaza, 20th Floor Mortgage Corp. Formerly, Vice Chairman of the Board
Baltimore, MD 21201 of Directors and President, Mercantile-Safe Deposit &
Trust Co.; and President, Mercantile Bankshares.
- --------------------------------------------------------------------------------------------------------------------------
JACK M. FIELDS (46) 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 (61) Trustee Partner, Kramer, Levin, Naftalis & Frankel (law
919 Third Avenue firm). Formerly, Partner, Reid & Priest (law firm).
New York, NY 10022
- --------------------------------------------------------------------------------------------------------------------------
*ROBERT H. GRAHAM (51) Trustee and Director, President and Chief Executive Officer,
President A I M Management Group Inc.; Director and President,
A I M Advisors, Inc.; 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.

A-5
<PAGE> 36

<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 (48) Trustee Chief Executive Officer, YWCA of the U.S.A.;
350 Fifth Avenue, Suite 301 Commissioner, New York City Department for the Aging;
New York, NY 10118 and Member of the Board of Directors, Metropolitan
Transportation Authority of New York State.
- --------------------------------------------------------------------------------------------------------------------------
LEWIS F. PENNOCK (56) Trustee Attorney in private practice in Houston, Texas.
6363 Woodway, Suite 825
Houston, TX 77057
- --------------------------------------------------------------------------------------------------------------------------
IAN W. ROBINSON (75) Trustee Formerly, Executive Vice President and Chief
183 River Drive Financial Officer, Bell Atlantic Management Services,
Tequesta, FL 33469 Inc. (provider of centralized management services to
telephone companies); Executive Vice President, Bell
Atlantic Corporation (parent of seven telephone
companies); and Vice President and Chief Financial
Officer, Bell Telephone Company of Pennsylvania and
Diamond State Telephone Company.
- --------------------------------------------------------------------------------------------------------------------------
LOUIS S. SKLAR (59) Trustee Executive Vice President, Development and Operations,
Transco Tower, 50th Floor Hines Interests Limited Partnership (real estate
2800 Post Oak Blvd. development).
Houston, TX 77056
- --------------------------------------------------------------------------------------------------------------------------
***JOHN J. ARTHUR (54) Senior Vice Director, Senior Vice President and Treasurer, A I M
President and Advisors, Inc.; and Vice President and Treasurer,
Treasurer A I M Management Group Inc., A I M Capital
Management, Inc., A I M Distributors, Inc., A I M
Fund Services, Inc. and Fund Management Company.
- --------------------------------------------------------------------------------------------------------------------------
GARY T. CRUM (51) Senior Vice Director and President, A I M Capital Management,
President Inc.; Director and Senior Vice President, A I M
Management Group Inc. and A I M Advisors, Inc.; and
Director, A I M Distributors, Inc. and AMVESCAP PLC.
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

- ---------------
***Mr. Arthur and Ms. Relihan are married to each other.

A-6
<PAGE> 37

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
POSITIONS HELD
NAME, ADDRESS AND AGE WITH REGISTRANT PRINCIPAL OCCUPATION DURING AT LEAST THE PAST 5 YEARS
- --------------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C>
***CAROL F. RELIHAN (44) Senior Vice Director, Senior Vice President, General Counsel and
President and Secretary, A I M Advisors, Inc.; Vice President,
Secretary 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 (39) Vice President Vice President and Fund Controller, A I M Advisors,
and Assistant Inc.; and Assistant Vice President and Assistant
Treasurer Treasurer, Fund Management Company.
- --------------------------------------------------------------------------------------------------------------------------
MELVILLE B. COX (55) 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 (38) Vice President Senior Vice President, A I M Capital Management, Inc.
and Vice President, A I M Advisors, Inc.
- --------------------------------------------------------------------------------------------------------------------------
J. ABBOTT SPRAGUE (43) Vice President Director and President, Fund Management Company;
11 Greenway Plaza, Suite 100 Director, A I M Fund Services, Inc.; and Senior Vice
Houston, TX 77046 President, A I M Advisors, Inc. and A I M Management
Group Inc.
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

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

***Mr. Arthur and Ms. Relihan are married to each other.

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, Fields,
Frischling, Pennock, Robinson (Chairman) and Sklar. 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, Robinson, and Sklar (Chairman). 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.

The members of the Nominating and Compensation Committee are Messrs. Crockett
(Chairman), Daly, Dunn, Fields, Pennock, Robinson and Sklar. 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 A I M Advisors, Inc.
("AIM") or distributed and administered by FMC. Most of the Trust's executive
officers hold similar offices with some or all of such investment companies.

A-7
<PAGE> 38

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
BENEFITS TOTAL
AGGREGATE ACCRUED COMPENSATION
COMPENSATION BY ALL FROM ALL
TRUSTEE FROM TRUST(1) AIM FUNDS(2) AIM FUNDS(3)
------- ------------- ------------- ------------
<S> <C> <C> <C>
Charles T. Bauer................................ $ -0- $ -0- $ -0-
Bruce L. Crockett............................... 4,747 67,774 84,000
Owen Daly II.................................... 4,747 103,542 84,000
Edward K. Dunn, Jr.(4).......................... 2,193 -0- -0-
Jack Fields..................................... 4,747 -0- 70,500
Carl Frischling................................. 4,747 96,520 84,000(5)
Robert H. Graham................................ -0- -0- -0-
John F. Kroeger(6).............................. 4,547 94,132 82,500
Prema Mathai-Davis(4)........................... 261 -0- -0-
Lewis F. Pennock................................ 4,747 55,777 84,000
Ian W. Robinson................................. 4,672 85,912 84,000
Louis S. Sklar.................................. 4,695 84,370 83,500
</TABLE>

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

(1) The total amount of compensation deferred by all Trustees of the Trust
during the fiscal year ended August 31, 1998, including interest earned
thereon, was $26,330.

(2) During the fiscal year ended August 31, 1998, the total amount of expenses
allocated to the Trust in respect of such retirement benefits was $32,407.
Data reflects compensation for the calendar year ended December 31, 1997.

(3) Each serves as a Director or Trustee of a total of 12 registered investment
companies advised by AIM as of December 31, 1997 (comprised of over 50
portfolios). Data reflects total compensation for the calendar year ended
December 31, 1997.

(4) Mr. Dunn and Ms. Mathai-Davis were not serving as Trustees during the
calendar year ended December 31, 1997.

(5) The Portfolio paid the law firm of Kramer, Levin, Naftalis & Frankel $4,488
in legal fees for services provided to the Portfolio during the fiscal year
ended August 31, 1998. Mr. Frischling, a trustee of the Trust, is a partner
in such firm.

(6) Mr. Kroeger resigned as a trustee on June 11, 1998 and on that date became a
consultant to the Trust.

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, A I M Management Group Inc. 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 AIM Funds. Each eligible trustee is
entitled to receive an annual benefit from the AIM Funds commencing on the first
day of the calendar quarter coincident with or following his date of retirement
equal to 75% of the retainer paid or accrued by the AIM Funds for such trustee
during the twelve-month period immediately preceding the trustee's retirement
(including amounts deferred under separate agreement between the AIM Funds and
the trustee) for the number of such trustee's years of service (not in excess of
10 years of service) completed with respect to any of the 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 AIM Fund.

A-8
<PAGE> 39

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, Fields, Dunn, Frischling, Kroeger, Pennock,
Robinson, Sklar and Ms. Mathai-Davis are 11, 10, 0, 1, 21, 20, 16, 11, 8 and 0
years, respectively.

ANNUAL RETAINER UPON RETIREMENT

<TABLE>
<CAPTION>
- ------------------------------------------------------------------------------------
NUMBER OF
YEARS OF
SERVICE WITH ANNUAL RETAINER PAID BY ALL AIM FUNDS
THE AIM FUNDS $90,000
<S> <C> <C> <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, Frischling, Kroeger, 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, 1998, $10,704 in trustees' fees and
expenses were allocated to the Portfolio.

INVESTMENT ADVISOR

A I M Advisors, Inc., 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173,
acts as the investment advisor of the Portfolio pursuant to a Master Investment
Advisory Agreement (the "Advisory Agreement"). AIM was organized in 1976, and
together with its subsidiaries advises or manages over 90 investment company
portfolios.

Pursuant to the terms of the Advisory Agreement, AIM manages the investment of
the assets of the Portfolio. AIM 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.

AIM and the Trust have adopted a Code of Ethics which requires investment
personnel (a) to pre-clear all personal securities transactions, (b) to file
reports regarding such transactions, and (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. The Code also prohibits investment personnel from purchasing
securities in an initial public offering. Personal trading reports are reviewed
periodically by AIM, and the Board of Trustees reviews annually such reports
(including information on any substantial violations of the Code). Violations of
the Code may result in censure, monetary penalties, suspension or termination of
employment.

A-9
<PAGE> 40

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 $250 million.......................................... .20%
Over $250 million to $500 million........................... .15%
Over $500 million........................................... .10%
</TABLE>

The Advisory Agreement requires AIM to reduce its fee to the extent required to
satisfy any expense limitations imposed by the securities laws or regulations
thereunder of any state in which the Portfolio's shares are qualified for sale.

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 (net of fee waivers, if any) from the Trust for the fiscal years ended
August 31, 1998, 1997 and 1996, with respect to the Portfolio in the amounts of
$412,610, $705,397 and $675,795, respectively. For the fiscal years ended August
31, 1998, 1997 and 1996, AIM waived fees with respect to the Portfolio in the
amounts of $167,622, $123,468 and $116,126, respectively.

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 certain
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."

The Advisory Agreement will continue in effect 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' written notice without penalty. The
Advisory Agreement terminates automatically in the event of its assignment, as
defined in the 1940 Act.

AIM is a wholly owned subsidiary of A I M Management Group Inc. ("AIM
Management"), 11 Greenway Plaza, Suite 100, Houston, Texas 77046-1173, a holding
company that has been engaged in the financial service business since 1976. 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 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.

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

ADMINISTRATIVE SERVICES

AIM also provides certain services pursuant to a Master Administrative
Services Agreement between AIM and the Trust (the "Administrative Services
Agreement").

Under the Administrative Services Agreement, AIM performs 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.

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 for the fiscal years ended August 31, 1998, 1997 and 1996, in
the amounts of $46,759, $56,844 and $30,056, respectively, for fund accounting
services for the Portfolio.

A-10
<PAGE> 41

EXPENSES

In addition to fees paid to AIM pursuant to the 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.

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.

TRANSFER AGENT AND CUSTODIAN

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.

A I M Fund Services, Inc. ("AFS"), a wholly owned subsidiary of AIM, P.O. Box
4497, Houston, TX 77210-4497, acts as transfer agent for the shares of all
classes of the Portfolio. 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. AFS has
provided transfer agency and shareholder services to the Portfolio since
December 29, 1997 pursuant to a Transfer Agency and Service Agreement. Prior to
December 29, 1997, A I M Institutional Fund Services, Inc., ("AIFS") provided
transfer agency and shareholder services to the Fund pursuant to a Transfer
Agency and Service Agreement.

A-11
<PAGE> 42

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 Peat Marwick LLP, 700 Louisiana, Houston, Texas
77002, as the independent auditors to audit the financial statements and review
the tax returns of the Portfolio.

FEE WAIVERS
AIM or its affiliates may, from time to time, agree to waive voluntarily all
or any portion of its fees or reimburse the Portfolio for certain of its
expenses. Such waivers or reimbursements may be discontinued at any time.

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 any class of the Government &
Agency Portfolio as of October 30, 1998, and the percentage of such shares owned
by such shareholders as of such date are as follows:
CASH MANAGEMENT CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
Fund Services Associates.................................. 59.52%(b)
1875 Century Park East -- Suite 1345
Los Angeles, CA 90067
Gardnyr Michael Capital, Inc.............................. 40.48%(b)
2281 Lee Rd. Ste. 104
Winter Park, FL 32789
</TABLE>

INSTITUTIONAL CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
Gardnyr Michael Capital, Inc.............................. 65.79%(b)
2281 Lee Rd. Ste. 104
Winter Park, FL 32789
Norwest Bank Mpls......................................... 34.11%
733 Marquette Ave.
Minneapolis, MN 55479-0052
</TABLE>

PRIVATE INVESTMENT CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
Fund Services Associates, Inc............................. 94.36%(b)
1875 Century Park East -- Suite 1345
Los Angeles, CA 90067
Huntington Capital Corp................................... 5.64%
41 S. High St., Ninth Floor
Columbus, OH 43287
</TABLE>

RESOURCE CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>

Hambrecht & Quist LLC..................................... 97.81%
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) 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.

A-12
<PAGE> 43

AIM provided the initial capitalization of the Personal Investment Class and
the Reserve Class of the Government & Agency Portfolio and, accordingly, as of
the date of this Statement of Additional Information, owned all the outstanding
shares of beneficial interest of each such Class. The Trust expects that the
sale of shares of such Classes to the public pursuant to the Prospectuses will
promptly reduce the percentage of such shares owned by AIM to less than 1% of
the total shares outstanding of such Classes.

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 any class of the Treasury
Portfolio as of October 30, 1998 and the percentage of such shares owned by such
shareholders as of such date are as follows:

CASH MANAGEMENT CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
Bank of New York.......................................... 57.31%
One Wall Street
5Th Floor
Stif/Master Note
New York, NY 10286
Fund Services Associates, Inc............................. 12.08%
1875 Century Park East -- Suite 1345
Los Angeles, CA 90067
Chase Bank of Texas....................................... 8.91%
600 Travis St., 8th Floor
8-CBT-39
Houston, TX 77252-8009
Bank of Oklahoma.......................................... 5.87%
P.O. Box 2180
Tulsa, OK 74101
</TABLE>

INSTITUTIONAL CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- -------------
<S> <C>
Trust Company Bank........................................ 8.20%
Center 3139
P.O. Box 105504
Atlanta, GA 30348
City of New York Deferred Compensation Plan............... 7.25%
40 Rector Street, 3rd Floor
New York, NY 10006
Weststar Bank Trust Dept.................................. 5.96%
P.O. Box 1156
Bartlesville, OK 74005-1156
First Trust/Var & Co...................................... 5.03%
Funds Control Suite 0404
180 East Fifth Street
St. Paul, MN 55101
</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.

A-13
<PAGE> 44

PERSONAL INVESTMENT CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
Cullen/Frost Discount Brokers............................. 67.44%
P.O. Box 2358
San Antonio, TX 78299
Bank of New York.......................................... 24.64%
4 Fisher Lane
White Plains, NY 10603
</TABLE>

PRIVATE INVESTMENT CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
The Bank of New York...................................... 26.49%
One Wall Street
5Th Floor
Stif/Master Note
New York, NY 10286
Huntington Capital Corp................................... 19.84%
41 S. High St., Ninth Floor
Columbus, OH 43287
Zions First National Bank................................. 13.19%
P.O. Box 30880
Salt Lake City, UT 84130
First Trust/Var & Co...................................... 8.45%
Funds Control Suite 0404
180 East 5th Street
St. Paul, MN 55101
New Haven Savings Bank Trust Department................... 6.74%
P.O. Box 302
Trust Department
New Haven, CT 06502
Midland First American.................................... 6.53%
One Erieview Plaza Ste. 500
Cleveland, OH 44114
Cullen/Frost Discount Brokers............................. 6.39%
P.O. Box 2358
San Antonio, TX 78299
</TABLE>

RESOURCE CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
First Union Capital Markets............................... 80.64%
8739 Research Drive
Capital Markets
Charlotte, NC 28262-0675
Mellon Bank NA............................................ 11.26%
P.O. Box 710
Pittsburgh, PA 15230-0710
</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.

A-14
<PAGE> 45

AIM provided the initial capitalization of the Reserve Class of the Treasury
Portfolio and, accordingly, as of the date of this Statement of Additional
Information, owned all the outstanding shares of beneficial interest of such
Class. The Trust expects that the sale of shares of such Class to the public
pursuant to its Prospectus will promptly reduce the percentage of such shares
owned by AIM to less than 1% of the total shares outstanding of such Class.

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 any class of the Portfolio as
of October 30, 1998 and the percentage of such shares owned by such shareholders
as of such date are as follows:

INSTITUTIONAL CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
First Trust/Var & Co...................................... 26.43%
Funds Control Suite 0404
180 East Fifth Street
St. Paul, MN 55101
Peoples Two Ten Company................................... 20.85%
P.O. Box 821
C/O Summit Bank
Hackensack, NJ 07602
Frost National Bank TX.................................... 12.17%
Muir & Co.
C/O Frost
P.O. Box 2479
San Antonio, TX 78298-2479
Everen Clearing Corp...................................... 6.60%
111 East Kilbourn Ave.
Milwaukee, WI 53202
Key Trust Company......................................... 6.48%
Mail Code OH-01-49-3040
4900 Tiedeman
Cleveland, OH 44101-5971
Nationsbank Texas......................................... 6.21%
1401 Elm Street 11Th Floor
P.O. Box 831000
Dallas, TX 75202-2911
Mason-Dixon Trust Company................................. 5.57%
45 W. Main Street
Westminister, 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.

A-15
<PAGE> 46

PRIVATE INVESTMENT CLASS

<TABLE>
<CAPTION>
PERCENT
NAME AND ADDRESS OWNED OF
OF RECORD OWNER Record Only(a)
---------------- --------------
<S> <C>
Huntington Capital Corp. ................................. 26.45%
41 S High St., Ninth Floor
Columbus, OH 43287
Bank of New York.......................................... 24.01%
One Wall Street
5Th Floor
Stif/Master Note
New York, NY 10286
First National Bank of Chicago............................ 18.69%
Mail Suite 0126
Attention Sweep Coordinator
Chicago, IL 60670-0126
Oppenheimer & Co., Inc.................................... 11.15%
Oppenheimer Tower
World Financial Center
New York, NY 10281
Hambrecht & Quist LLC..................................... 8.79%
1100 Newport Center Drive, Second Floor
Newport Beach, CA 92660
First Union Capital Markets............................... 8.65%
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.

AIM provided the initial capitalization of the Cash Management Class, Personal
Investment Class, Reserve Class and Resource Class of the Portfolio and,
accordingly, as of the date of this Statement of Additional Information, owned
all the outstanding shares of beneficial interest of each such Class. The Trust
expects that the sale of shares of each such Class to the public pursuant to its
Prospectuses will promptly reduce the percentage of such shares owned by AIM to
less than 1% of the total shares outstanding of each such Class.

Shares shown as beneficially owned by the above institutions are those shares
for which the institutions possessed or shared voting or investment power with
respect to such shares on behalf of their underlying accounts.

To the best of the knowledge of the Trust, as of October 30, 1998, the
trustees and officers of the Trust beneficially owned less than 1% of each class
of the Trust's outstanding shares.

PURCHASES AND REDEMPTIONS

A complete description of the manner by which shares of a particular class may
be purchased, redeemed or exchanged appears in each Prospectus under the heading
"Purchase of Shares."

The right of redemption may be suspended or the date of payment postponed when
(a) trading on the New York Stock Exchange ("NYSE") is restricted, as determined
by applicable rules and regulations of the SEC, (b) the NYSE is closed for other
than customary weekend and holiday closings, (c) the SEC has by order permitted
such suspension, or (d) an emergency as determined by the SEC exists making
disposition of portfolio securities or the valuation of the net assets of the
Fund not reasonably practicable.

A "business day" of the Portfolio is any day on which commercial banks in the
New York Federal Reserve district are open for business. The Portfolio, however,
reserves the right to change the time for which purchase and redemption requests
must be

A-16
<PAGE> 47

submitted to the Portfolio for execution on the same day on any day when the
U.S. primary broker-dealer community is closed for business or trading is
restricted due to national holidays.

NET ASSET VALUE DETERMINATION

Shares of each class of the Portfolio are sold at the net asset value of such
shares. Shareholders may at any time redeem all or a portion of their shares at
net asset value. The investor's price for purchases and redemptions will be the
net asset value next determined following the receipt of an order to purchase or
a request to redeem shares.

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, which require the Trust to adhere to certain
conditions. These rules require that the Fund 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 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 sale 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.
FMC does not receive any fees with respect to the shares of the Institutional
Class pursuant to the Distribution Agreement.

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 sixty days' written notice without
penalty. The Distribution Agreement will terminate automatically in the event of
its "assignment," as defined in the 1940 Act.

DISTRIBUTION PLAN

The Trust has adopted a Master Distribution Plan (the "Plan") pursuant to Rule
12b-1 under the 1940 Act. 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 the class of customer
cash account balances in shares of these classes; (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;

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(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.

For the fiscal year ended August 31, 1998, FMC received compensation pursuant
to the Plan in the amount of $90,969, or an amount equal to 0.25% of the average
daily net assets of the Private Investment Class. With respect to the Private
Investment Class, all of such amount was paid to dealers and financial
institutions and none of such compensation was retained by FMC.

FMC is a wholly owned subsidiary of AIM, a wholly owned subsidiary of AIM
Management. Charles T. Bauer, a Trustee and Chairman of the Trust, owns shares
of AIM Management and Robert H. Graham, a Trustee and President of the Trust,
also owns shares of AIM Management.

PERFORMANCE INFORMATION

As stated under the caption "Yield Information" in each Prospectus, yield
information for the shares of each class of the Portfolio may be obtained by
calling the Trust at (800) 659-1005. The current yield quoted will be the net
average annualized yield for an identified period, such as seven days or a
month. Current yield 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 realized gains and losses or
unrealized appreciation or depreciation) 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 yield that assumes the reinvestment of dividends for a 365-day year
and a return for the entire year equal to the average annualized yield for the
period, which will be computed by compounding the unannualized current yield for
the period by adding 1 to the unannualized current yield, raising the sum to a
power equal to 365 divided by the number of days in the period, and then
subtracting 1 from the result.

For the seven-day period ended August 31, 1998, the current yield and the
effective yield (which assumes the reinvestment of dividends for a 365-day year
and a return for the entire year equal to the annualized current yield for the
period) for the Institutional Class were 4.99% and 5.11% and for the Private
Investment Class were 4.74% and 4.85%, respectively. These performance numbers
are quoted for illustration purposes only. Performance numbers for any other
seven-day period may be substantially different from those quoted above.

The Trust may compare the performance of a particular 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 of Holliston, Massachusetts or by Lipper
Analytical Services, Inc., a widely recognized independent service located
in Summit, New Jersey, 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 the yield of a class 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's securities 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.

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INVESTMENT PROGRAM AND RESTRICTIONS
INVESTMENT PROGRAM

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 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.

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) 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 or 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;

(3) 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;

(4) 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;

(5) 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;

(6) 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;

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

(8) 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 applicable
law or exemptive order. 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 judgment, the income to be earned from the loans justifies
the attendant risks. None of the foregoing policies is fundamental.

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PORTFOLIO TRANSACTIONS

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 portfolio 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.

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.

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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 or in
written form. 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.

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.

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 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.

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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
each 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
each Prospectus is not intended as a substitute for careful tax planning.

QUALIFICATIONS 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 the Portfolio's taxable
year, at least 50% of the value of the Portfolio'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 the Portfolio
has not invested more than 5% of the value of the Portfolio's total assets in
securities of such issuer and as to which the Portfolio 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 the Portfolio 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 in accordance with the guidance that has been
provided by the Internal Revenue Service.

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.

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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,
distributions 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 distributions are actually made 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.

The Portfolio will be required in certain cases to withhold and remit to the
U.S. Treasury 31% of ordinary income dividends and capital gain dividends, and
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 Portfolio 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 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.

EFFECT OF FUTURE LEGISLATION; STATE AND 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 December
18, 1998. 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.

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FINANCIAL STATEMENTS

FS
<PAGE> 55

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 the
Treasury TaxAdvantage Portfolio (a series portfolio of Short-Term Investments
Trust), including the schedule of investments, as of August 31, 1998, and the
related statement of operations for the year then ended, the statements of
changes in net assets for each of the years in the two-year period then ended,
and the financial highlights for each of the years in the five-year period then
ended. 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
audits.
We conducted our audits 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, 1998, 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 audits provide 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 the
Treasury TaxAdvantage Portfolio as of August 31, 1998, the results of its
operations for the year then ended, the changes in its net assets for each of
the years in the two-year period then ended, and the financial highlights for
each of the years in the five-year period then ended, in conformity with
generally accepted accounting principles.

KPMG Peat Marwick LLP

Houston, Texas
October 2, 1998

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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 the
Treasury TaxAdvantage Portfolio (a series portfolio of Short-Term Investments
Trust), including the schedule of investments, as of August 31, 1998, and the
related statement of operations for the year then ended, the statements of
changes in net assets for each of the years in the two-year period then ended,
and the financial highlights for each of the years in the three-year period
then ended and the period December 21, 1994 (date sales commenced for the
Private Investment Class) through August 31, 1995. 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 audits.
We conducted our audits 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, 1998, 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 audits provide 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 the
Treasury TaxAdvantage Portfolio as of August 31, 1998, the results of its
operations for the year then ended, the changes in its net assets for each of
the years in the two-year period then ended, and the financial highlights for
each of the years in the three-year period then ended and the period December
21, 1994 (date sales commenced for the Private Investment Class) through August
31, 1995, in conformity with generally accepted accounting principles.

KPMG Peat Marwick LLP

Houston, Texas
October 2, 1998

FS-2
<PAGE> 57
SCHEDULE OF INVESTMENTS
August 31, 1998

<TABLE>
<CAPTION>
PAR
MATURITY (000) VALUE
<S> <C> <C> <C>
U.S. TREASURY SECURITIES - 98.98%

U.S. TREASURY BILLS(a) - 42.76%
5.38% 09/15/98 $17,000 $ 16,964,432
- ------------------------------------------------------------------------
4.91% 10/08/98 1,500 1,492,430
- ------------------------------------------------------------------------
4.92% 10/08/98 1,500 1,492,415
- ------------------------------------------------------------------------
4.94% 10/22/98 6,200 6,156,610
- ------------------------------------------------------------------------
4.95% 10/22/98 6,000 5,957,925
- ------------------------------------------------------------------------
4.90% 10/29/98 1,700 1,686,580
- ------------------------------------------------------------------------
4.94% 10/29/98 4,500 4,464,185
- ------------------------------------------------------------------------
4.96% 10/29/98 3,000 2,976,027
- ------------------------------------------------------------------------
4.88% 11/12/98 3,000 2,970,720
- ------------------------------------------------------------------------
4.89% 11/12/98 3,500 3,465,770
- ------------------------------------------------------------------------
4.92% 11/12/98 3,900 3,861,624
- ------------------------------------------------------------------------
4.925% 11/12/98 4,000 3,960,600
- ------------------------------------------------------------------------
4.83% 11/27/98 6,300 6,226,463
- ------------------------------------------------------------------------
61,675,781
- ------------------------------------------------------------------------

U.S. TREASURY NOTES - 56.22%

6.00% 09/30/98 20,000 20,011,434
- ------------------------------------------------------------------------
5.875% 10/31/98 30,000 30,015,678
- ------------------------------------------------------------------------
5.50% 11/15/98 10,000 10,002,191
- ------------------------------------------------------------------------
8.875% 11/15/98 6,000 6,041,836
- ------------------------------------------------------------------------
5.625% 11/30/98 15,000 15,014,104
- ------------------------------------------------------------------------
81,085,243
- ------------------------------------------------------------------------
Total U.S. Treasury Securities
(Cost $142,761,024) 142,761,024
- ------------------------------------------------------------------------
TOTAL INVESTMENTS -- 98.98% 142,761,024(b)
- ------------------------------------------------------------------------
OTHER ASSETS LESS LIABILITIES -- 1.02% 1,466,178
- ------------------------------------------------------------------------
NET ASSETS -- 100.00% $144,227,202
========================================================================
</TABLE>
(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) Also represents cost for federal income tax purposes.

See Notes to Financial Statements.

FS-3
<PAGE> 58
STATEMENT OF ASSETS AND LIABILITIES
August 31, 1998

<TABLE>
<S> <C>
ASSETS:
Investments, at value (amortized cost) $142,761,024
- ----------------------------------------------------------------------
Cash 535,982
- ----------------------------------------------------------------------
Interest receivable 1,633,831
- ----------------------------------------------------------------------
Investment for deferred compensation plan 25,086
- ----------------------------------------------------------------------
Other assets 1,534
- ----------------------------------------------------------------------
Total assets 144,957,457
- ----------------------------------------------------------------------

LIABILITIES:
Payables for:
Dividends 636,264
- ----------------------------------------------------------------------
Deferred compensation 25,086
- ----------------------------------------------------------------------
Accrued administrative services fees 3,987
- ----------------------------------------------------------------------
Accrued advisory fees 12,942
- ----------------------------------------------------------------------
Accrued distribution fees 7,410
- ----------------------------------------------------------------------
Accrued transfer agent fees 6,199
- ----------------------------------------------------------------------
Accrued trustees' fees 2,195
- ----------------------------------------------------------------------
Accrued operating expenses 36,172
- ----------------------------------------------------------------------
Total liabilities 730,255
- ----------------------------------------------------------------------
NET ASSETS $144,227,202
======================================================================
NET ASSETS:
Institutional Class $113,084,306
======================================================================
Private Investment Class $ 31,142,896
======================================================================
SHARES OF BENEFICIAL INTEREST, $.01 PAR VALUE PER SHARE:
Institutional Class 113,050,692
======================================================================
Private Investment Class 31,133,639
======================================================================
NET ASSET VALUE PER SHARE:
Net asset value, offering and redemption price per share $ 1.00
======================================================================
</TABLE>

See Notes to Financial Statements.

FS-4
<PAGE> 59

STATEMENT OF OPERATIONS
For the year ended August 31, 1998

<TABLE>
<S> <C>
INVESTMENT INCOME:
Interest income $10,833,975
- ------------------------------------------------------------------

EXPENSES:
Advisory fees 412,610
- ------------------------------------------------------------------
Custodian fees 10,804
- ------------------------------------------------------------------
Administrative services fees 46,759
- ------------------------------------------------------------------
Trustees' fees and expenses 10,704
- ------------------------------------------------------------------
Transfer agent fees 34,933
- ------------------------------------------------------------------
Distribution fees (Note 2) 181,938
- ------------------------------------------------------------------
Other 66,389
- ------------------------------------------------------------------
Total expenses 764,137
- ------------------------------------------------------------------
Less: Fee waivers (258,591)
- ------------------------------------------------------------------
Net expenses 505,546
- ------------------------------------------------------------------
Net investment income 10,328,429
- ------------------------------------------------------------------
Net realized gain on sales of investments 42,871
- ------------------------------------------------------------------
Net increase in net assets resulting from operations $10,371,300
==================================================================
</TABLE>

See Notes to Financial Statements.

FS-5
<PAGE> 60

STATEMENT OF CHANGES IN NET ASSETS
For the years ended August 31, 1998 and 1997

<TABLE>
<CAPTION>
1998 1997
------------ -------------
<S> <C> <C>
OPERATIONS:
Net investment income $ 10,328,429 $ 19,242,512
- --------------------------------------------------------------------------
Net realized gain on sales of investments 42,871 77,371
- --------------------------------------------------------------------------
Net increase in net assets resulting from
operations 10,371,300 19,319,883
- --------------------------------------------------------------------------
Distributions to shareholders from net
investment income:
Institutional Class (8,586,021) (16,879,485)
- --------------------------------------------------------------------------
Private Class (1,742,408) (2,363,027)
- --------------------------------------------------------------------------
Distributions to shareholders from capital
gains:
Institutional Class (154,304) --
- --------------------------------------------------------------------------
Private Class (47,000) --
- --------------------------------------------------------------------------
Share transactions-net (See Note 4) (153,177,145) (159,710,741)
- --------------------------------------------------------------------------
Net increase (decrease) in net assets (153,335,578) (159,633,370)
- --------------------------------------------------------------------------

NET ASSETS:
Beginning of period 297,562,780 457,196,150
- --------------------------------------------------------------------------
End of period $144,227,202 $ 297,562,780
==========================================================================
NET ASSETS CONSIST OF:
Shares of beneficial interest $144,184,331 $ 297,361,476
- --------------------------------------------------------------------------
Undistributed net realized gain on sales of
investments 42,871 201,304
- --------------------------------------------------------------------------
$144,227,202 $ 297,562,780
==========================================================================
</TABLE>

See Notes to Financial Statements.

FS-6
<PAGE> 61

NOTES TO FINANCIAL STATEMENTS
August 31, 1998

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 TaxAdvantage Portfolio, the Government & Agency
Portfolio and the Treasury Portfolio. The Government & Agency Portfolio
commenced operations on September 1, 1998. Information presented in these
financial statements pertains only to the Treasury TaxAdvantage Portfolio (the
"Portfolio") with the assets, liabilities and operations of each portfolio
accounted for separately. The Portfolio consists of two different classes of
shares: the Institutional Class and the Private Investment 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 these
financial statements and the reported amount of revenues and expenses during
the reporting period. Actual results could differ from those estimates. The
following is a summary of the 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 which are
attributable to more than one class are allocated between 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:

<TABLE>
<CAPTION>
Net Assets RATE
- ----------------------------------------
<S> <C>
First $250 million 0.20%
- ----------------------------------------
Over $250 million to $500 million 0.15%
- ----------------------------------------
Over $500 million 0.10%
- ----------------------------------------
</TABLE>

During the year ended August 31, 1998, AIM voluntarily waived advisory fees of
$167,622.
The Portfolio, pursuant to a master administrative services agreement with
AIM, has agreed to reimburse AIM for certain costs incurred in providing
accounting services to the Portfolio. During the year ended August 31, 1998,
the Portfolio reimbursed AIM $46,759 for such services.
The Portfolio, 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 Portfolio. On September 20, 1997, the Board of
Trustees

FS-7
<PAGE> 62

approved the appointment of AFS as transfer agent of the Fund effective
December 29, 1997. During the year ended August 31, 1998, the Portfolio paid
AFS $19,384 for such services. Prior to the effective date of this agreement
with AFS, the Portfolio paid A I M Institutional Fund Services, Inc. $8,009
pursuant to a transfer agency and shareholder services agreement for the period
September 1, 1997 through December 28, 1997.
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 Plan provides that the Private Investment Class may pay
up to a 0.50% maximum annual rate of the Private Investment Class' average
daily net assets. Of this amount, the Fund may pay an asset-based sales charge
to FMC and the Fund may pay a service fee of 0.25% of the average daily net
assets of the Private Investment 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.
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 the Private Investment Class. During the year ended
August 31, 1998, the Private Investment Class paid $90,969 as compensation
under the Plan. FMC waived fees of $90,969 for the same period. Certain
officers and trustees of the Trust are officers of AIM, FMC and AFS.
During the year ended August 31, 1998, the Portfolio paid legal fees of $4,488
for services rendered by Kramer, Levin, Naftalis & Frankel 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 or accrued to each trustee who is
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.

NOTE 4-SHARE INFORMATION

Changes in shares outstanding during the years ended August 31, 1998 and 1997
were as follows:

<TABLE>
<CAPTION>
1998 1997
--------------------------- ------------------------------
SHARES AMOUNT SHARES AMOUNT
------------ ------------- -------------- --------------
<S> <C> <C> <C> <C>
Sold:
Institutional Class 758,084,286 $ 758,084,286 1,249,698,433 $1,249,698,433
- -----------------------------------------------------------------------------------
Private Investment
Class 314,695,955 314,695,955 274,981,089 274,981,089
- -----------------------------------------------------------------------------------
Issued as reinvestment
of dividends:
Institutional Class 368,100 368,100 425,111 425,111
- -----------------------------------------------------------------------------------
Private Investment
Class 774,188 774,188 479,712 479,712
- -----------------------------------------------------------------------------------
Reacquired:
Institutional Class (903,477,854) (903,477,854) (1,399,155,040) (1,399,155,040)
- -----------------------------------------------------------------------------------
Private Investment
Class (323,621,820) (323,621,820) (286,140,046) (286,140,046)
- -----------------------------------------------------------------------------------
Net increase
(decrease) (153,177,145) $(153,177,145) (159,710,741) $ (159,710,741)
- -----------------------------------------------------------------------------------
</TABLE>

FS-8
<PAGE> 63

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Institutional Class
outstanding during each of the years in the five-year period ended August 31,
1998.

<TABLE>
<CAPTION>
1998 1997 1996 1995 1994
-------- -------- -------- -------- --------
<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 0.03
- ------------------------- -------- -------- -------- -------- --------
Total from investment
operations 0.05 0.05 0.05 0.05 0.03
- ------------------------- -------- -------- -------- -------- --------
Less distributions:
Dividends from net
investment income (0.05) (0.05) (0.05) (0.05) (0.03)
- ------------------------- -------- -------- -------- -------- --------
Total distributions (0.05) (0.05) (0.05) (0.05) (0.03)
- ------------------------- -------- -------- -------- -------- --------
Net asset value, end of
period $ 1.00 $ 1.00 $ 1.00 $ 1.00 $ 1.00
========================= ======== ======== ======== ======== ========
Total return 5.30% 5.13% 5.19% 5.35% 3.29%
========================= ======== ======== ======== ======== ========
Ratios/supplemental data:
Net assets, end of period
(000s omitted) $113,084 $258,251 $407,218 $394,376 $403,882
========================= ======== ======== ======== ======== ========
Ratio of expenses to
average net assets(a) 0.20%(b) 0.20% 0.20% 0.20% 0.20%
========================= ======== ======== ======== ======== ========
Ratio of net investment
income to average net
assets(c) 5.05%(b) 5.00% 5.06% 5.21% 3.23%
========================= ======== ======== ======== ======== ========
</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
0.28%, 0.23%, 0.23%, 0.23% and 0.23% for the periods 1998-1994,
respectively.
(b) Ratios are based on average net assets of $169,918,161.
(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 4.97%, 4.97%, 5.04%, 5.18% and 3.20% for the periods
1998-1994, respectively.

FS-9
<PAGE> 64

NOTE 5-FINANCIAL HIGHLIGHTS

Shown below are the financial highlights for a share of the Private Investment
Class outstanding during each of the years in the three-year period ended
August 31, 1998 and the period December 21, 1994 (date sales commenced) through
August 31, 1995.

<TABLE>
<CAPTION>
1998 1997 1996 1995
------- ------- ------- ------
<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 0.04
- ------------------------------------- ------- ------- ------- ------
Total from investment operations 0.05 0.05 0.05 0.04
- ------------------------------------- ------- ------- ------- ------
Less distributions:
Dividends from net investment income (0.05) (0.05) (0.05) (0.04)
- -------------------------------------- ------ ------- ------- ------
Total distributions (0.05) (0.05) (0.05) (0.04)
- -------------------------------------- ------ ------- ------- ------
Net asset value, end of period $ 1.00 $ 1.00 $ 1.00 $ 1.00
====================================== ======= ======= ======= ======
Total return 5.04% 4.87% 4.93% 5.32%(a)
====================================== ======= ======= ======= ======
Ratios/supplemental data:
Net assets, end of period (000s
omitted) $31,143 $39,312 $49,978 $5,423
====================================== ======= ======= ======= ======
Ratio of expenses to average net
assets(b) 0.45%(c) 0.45% 0.45% 0.45%(a)
====================================== ======= ======= ======= ======
Ratio of net investment income to
average net assets(d) 4.80%(c) 4.75% 4.72% 5.21%(a)
====================================== ======= ======= ======= ======
</TABLE>
(a) Annualized.
(b) After fee waivers and/or expense reimbursements. Ratios of expenses to
average net assets prior to fee waivers and/or expense reimbursements were
0.78%, 0.74%, 0.85% and 1.02% (annualized) for the periods 1998-1995,
respectively.
(c) Ratios are based on average net assets of $36,387,542.
(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 4.47%, 4.46%, 4.32% and 4.64% (annualized) for the
periods 1998-1995, respectively.

FS-10
<PAGE> 65
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
SHORT-TERM INVESTMENTS TRUST
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 659-1005

INVESTMENT ADVISOR
A I M ADVISORS, INC.
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(713) 626-1919

DISTRIBUTOR
FUND MANAGEMENT COMPANY
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 659-1005

AUDITORS
KPMG PEAT MARWICK LLP
700 Louisiana
Houston, Texas 77002

CUSTODIAN
THE BANK OF NEW YORK
90 Washington Street,
11th Floor
New York, New York 10286

TRANSFER AGENT
A I M FUND SERVICES, INC.
P.O. Box 4497,
Houston, TX 77210-4497

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS IN CONNECTION WITH THE OFFERING
MADE BY THIS PROSPECTUS, AND IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE TRUST
OR THE DISTRIBUTOR. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER IN ANY
JURISDICTION TO ANY PERSON TO WHOM SUCH OFFERING MAY NOT LAWFULLY BE MADE.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

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

PROSPECTUS

December 18, 1998
SHORT-TERM
INVESTMENTS TRUST
---------------------

TREASURY TAXADVANTAGE
PORTFOLIO
---------------------

INSTITUTIONAL CLASS

TABLE OF CONTENTS
<TABLE>
<CAPTION>
PAGE
<S> <C>
Summary........................................... 2
Table of Fees and Expenses........................ 4
Financial Highlights.............................. 5
Suitability for Investors......................... 6
Investment Program................................ 6
Purchase of Shares................................ 8
Redemption of Shares.............................. 8
Dividends......................................... 9
Taxes............................................. 10
Net Asset Value................................... 10
Yield Information................................. 10
Reports to Shareholders........................... 11
Management of the Trust........................... 11
General Information............................... 12
Appendix.......................................... A-1
</TABLE>
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE> 66

PROSPECTUS

PERSONAL INVESTMENT CLASS
OF THE
TREASURY TAXADVANTAGE PORTFOLIO
OF
SHORT-TERM INVESTMENTS TRUST
11 GREENWAY PLAZA, SUITE 100
HOUSTON, TEXAS 77046-1173
(800) 877-7748

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

The Treasury TaxAdvantage 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 Treasury
TaxAdvantage Portfolio seeks to achieve its objective by investing in direct
obligations of the U.S. Treasury. The Treasury TaxAdvantage Portfolio's
investment strategy is intended to enable the Portfolio to provide its
shareholders with dividends that are exempt from state and local income taxation
in certain jurisdictions. The instruments purchased by the Treasury TaxAdvantage
Portfolio will have maturities of 397 days or less.

---------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION NOR HAS THE SECURITIES AND EXCHANGE COMMISSION PASSED UPON
THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY
IS A CRIMINAL OFFENSE.
---------------------

THIS PROSPECTUS SETS FORTH BASIC INFORMATION THAT A PROSPECTIVE INVESTOR
SHOULD KNOW BEFORE INVESTING IN SHARES OF THE PERSONAL INVESTMENT CLASS OF THE
TREASURY TAXADVANTAGE PORTFOLIO AND SHOULD BE READ AND RETAINED FOR FUTURE
REFERENCE. A STATEMENT OF ADDITIONAL INFORMATION, DATED DECEMBER 18, 1998, HAS
BEEN FILED WITH THE UNITED STATES SECURITIES AND EXCHANGE COMMISSION (THE "SEC")
AND IS HEREBY INCORPORATED BY REFERENCE. FOR A COPY OF THE STATEMENT OF
ADDITIONAL INFORMATION WITHOUT CHARGE, WRITE TO THE ADDRESS ABOVE OR CALL (800)
877-4744. THE SEC MAINTAINS A WEB SITE AT HTTP://WWW.SEC.GOV THAT CONTAINS THE
STATEMENT OF ADDITIONAL INFORMATION, MATERIAL INCORPORATED BY REFERENCE, AND
OTHER INFORMATION REGARDING THE TRUST.

THE TRUST'S SHARES ARE NOT DEPOSITS OR OBLIGATIONS OF, OR GUARANTEED OR
ENDORSED BY, ANY BANK, AND THE TRUST'S SHARES ARE NOT FEDERALLY INSURED OR
GUARANTEED BY THE U.S. GOVERNMENT, THE FEDERAL DEPOSIT INSURANCE CORPORATION,
THE FEDERAL RESERVE BOARD OR ANY OTHER AGENCY. THERE CAN BE NO ASSURANCE THAT
THE TREASURY TAXADVANTAGE PORTFOLIO WILL BE ABLE TO MAINTAIN A STABLE NET ASSET
VALUE OF $1.00 PER SHARE. SHARES OF THE TRUST INVOLVE INVESTMENT RISKS,
INCLUDING THE POSSIBLE LOSS OF PRINCIPAL.

PROSPECTUS DATED: DECEMBER 18, 1998
<PAGE> 67

TABLE OF CONTENTS

<TABLE>
<CAPTION>
PAGE
<S> <C>
SUMMARY........................................... 2
TABLE OF FEES AND EXPENSES........................ 4
SUITABILITY FOR INVESTORS......................... 5
INVESTMENT PROGRAM................................ 5
PURCHASE OF SHARES................................ 7
REDEMPTION OF SHARES.............................. 9
DIVIDENDS......................................... 10
</TABLE>

<TABLE>
<CAPTION>
PAGE
<S> <C>
TAXES............................................. 11
NET ASSET VALUE................................... 11
YIELD INFORMATION................................. 12
REPORTS TO SHAREHOLDERS........................... 12
MANAGEMENT OF THE TRUST........................... 13
GENERAL INFORMATION............................... 15
</TABLE>

SUMMARY

THE PORTFOLIO AND ITS INVESTMENT OBJECTIVE

The Trust is an open-end diversified series management investment company.
This Prospectus relates to the Personal Investment Class (the "Class") of the
Treasury TaxAdvantage Portfolio (the "Portfolio"). The Portfolio is a money
market fund which invests in direct obligations of the U.S. Treasury. The
instruments purchased by the Portfolio will have maturities of 397 days or less.
The investment objective of the Portfolio is the maximization of current income
to the extent consistent with the preservation of capital and the maintenance of
liquidity. The Portfolio's investment strategy is intended to enable the
Portfolio to provide its shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions.

Pursuant to separate prospectuses, the Trust also offers other classes of
shares of beneficial interest representing interests in the Portfolio: the Cash
Management Class, the Institutional Class, the Private Investment Class, the
Reserve Class and the Resource Class. Such classes have different distribution
arrangements and are designed for different types of investors. The Trust also
offers shares of several classes representing interests in each of two other
portfolios, the Government & Agency Portfolio and the Treasury Portfolio,
pursuant to separate prospectuses. The portfolios of the Trust are referred to
collectively as "Portfolios."

INVESTORS IN THE CLASS

The Class is designed to be a convenient vehicle in which customers of
banks, certain broker-dealers and other financial institutions can invest in a
diversified open-end money market fund.

PURCHASE OF SHARES

Shares of the Class that are offered hereby are sold at net asset value.
The minimum initial investment in the Class is $1,000. There is no minimum
amount for subsequent investments. Payment for shares of the Class purchased
must be in funds immediately available to the Trust. See "Purchase of Shares."

REDEMPTION OF SHARES

2
<PAGE> 68

DIVIDENDS

CONSTANT NET ASSET VALUE

The Trust uses the amortized cost method of valuing the securities held by
the Portfolio and rounds the per share net asset value to the nearest whole
cent. Accordingly, the net asset value per share of the Portfolio will normally
remain constant at $1.00. AN INVESTMENT IN THE PORTFOLIO IS NOT INSURED OR
GUARANTEED BY THE U.S. GOVERNMENT, AND THERE IS NO ASSURANCE THAT THE PORTFOLIO
WILL BE ABLE TO MAINTAIN A STABLE NET ASSET VALUE. See "Net Asset Value."

INVESTMENT ADVISOR

DISTRIBUTOR AND DISTRIBUTION PLAN

Fund Management Company ("FMC") acts as the exclusive distributor of the
shares of the Class. Pursuant to a plan of distribution adopted by the Trust's
Board of Trustees, the Trust may pay up to 0.75% of the average daily net asset
value of the Portfolio attributable to the Class to FMC as well as to certain
broker-dealers or other financial institutions. Of this amount, up to 0.25% may
be for continuing personal services to shareholders provided by broker-dealers
or institutions and the balance would be deemed an asset-based sales charge. See
"Purchase of Shares" and "Distribution Plan."

SPECIAL RISK CONSIDERATIONS

ANNUAL PORTFOLIO OPERATING EXPENSES -- PERSONAL INVESTMENT
CLASS (AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management fees (after fee waivers)**..................... 0.12%
12b-1 fees (after fee waivers)**.......................... 0.50%***
Other expenses (estimated):
Custodian fees......................................... 0.01%
Other.................................................. 0.07%
------
Total other expenses.............................. 0.08%
------
Total portfolio operating expenses -- Personal Investment
Class**................................................ 0.70%
======
</TABLE>

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

* Beneficial owners of shares of the Class should consider the effect of any
charges imposed by their bank, broker-dealer or financial institution for
various services.
** Had there been no fee waivers, Management fees, 12b-1 fees and Total
portfolio operating expenses would be 0.20%, 0.75% and 1.03%, respectively.
*** It is possible that as a result of Rule 12b-1 fees, long-term shareholders
may pay more than the economic equivalent of the maximum front-end sales
charges permitted under rules of the National Association of Securities
Dealers, Inc. Given the Rule 12b-1 fee of the Class, however, it is
estimated that it would take a substantial number of years for a shareholder
to exceed such maximum front-end sales charges.

EXAMPLE

An investor in the Class would pay the following expenses on a $1,000
investment, assuming (1) a 5% annual return and (2) redemption at the end of
each time period.

<TABLE>
<S> <C>
1 year..................................................... $ 7
3 years.................................................... $22
</TABLE>

4
<PAGE> 70

estimates. The Table of Fees and Expenses reflects voluntary waivers for the
Class. Future waivers of fees (if any) may vary from the figures reflected in
the Table of Fees and Expenses. To the extent any service providers assume
additional expenses of the Class, such assumption of additional expenses will
have the effect of lowering the Class's overall expense ratio and increasing its
yield to investors. Beneficial owners of shares of the Class should also
consider the effect of any charges imposed by the institution maintaining their
accounts.

The example in the Table of Fees and Expenses assumes that all dividends
and distributions are reinvested and that the amounts listed under "Annual
Portfolio Operating Expenses -- Personal Investment Class" remain the same in
the years shown.

SUITABILITY FOR INVESTORS

Investors in the 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 Class.

INVESTMENT PROGRAM
INVESTMENT OBJECTIVE

INVESTMENT POLICIES

5
<PAGE> 71

will generally have decreased. Conversely, if yields have decreased, the market
value of such security will generally have increased.

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

The investment policies described above may be changed by the Board of
Trustees without the affirmative vote of a majority of the outstanding shares of
beneficial interest of the Trust.

6
<PAGE> 72

INVESTMENT RESTRICTIONS

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. The
Portfolio will not purchase securities while borrowings in excess of 5% of
its total assets are outstanding.

PURCHASE OF SHARES

Shares of the Class are sold on a continuing basis at their net asset value next
determined after an order has been received by the Portfolio. As discussed
below, the Trust reserves the right to reject any purchase order. Although there
is no sales charge imposed on the purchase of shares of the Class, banks or
other institutions may charge a recordkeeping, account maintenance or other fee
to their customers, and beneficial holders of the shares of the Class should
consult with the institutions maintaining their accounts to obtain a schedule of
applicable fees. To facilitate the investment of proceeds of purchase orders,
investors are urged to place their orders as early in the day as possible.
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 3:00 p.m. Eastern Time on a business day of the Portfolio. Purchase
orders received after such time will be processed at the next day's net asset
value. Following the initial investment, subsequent purchases of shares of the
Class may also be made via AIM LINK--Registered Trademark-- Remote, a personal
computer application software product. Shares of the Class will earn the
dividend declared on the effective date of purchase.

qualified accounts at an Institution may invest in the shares of the Class. Each
Institution will render administrative support services to its customers who are
the beneficial owners of the shares of the Class. Such services may include,
among other things, establishment and maintenance of shareholder accounts and
records; assistance in processing purchase and redemption transactions in shares
of the Class; providing periodic statements showing a customer's account balance
in shares of the Class; distribution of Trust proxy statements, annual reports
and other communications to shareholders whose accounts are serviced by the
Institution; and such other services as the Trust may reasonably request.
Institutions will be required to certify to the Trust that they comply with
applicable state law regarding registration as broker-dealers, or that they are
exempt from such registration.

Prior to the initial purchase of shares of the Class, an Account
Application, which can be obtained from the Transfer Agent, must be completed
and sent to the Transfer Agent at P.O. Box 4497, Houston, TX 77210-4497. Any
changes made to the information provided in the Account Application must be made
in writing or by completing a new form and providing it to the Transfer Agent.
An investor must open an account in the shares of the Class through an
Institution in accordance with procedures established by such Institution. Each
Institution separately determines the rules applicable to accounts in the shares
of the Class opened with it, including minimum initial and subsequent investment
requirements and the procedures to be followed by investors to effect purchases
of shares of the Class. The minimum initial investment is $1,000, and there is
no minimum amount of subsequent purchases of shares of the Class by an
Institution on behalf of its customers. An investor who proposes to open a
Portfolio account with an Institution should consult with a representative of
such Institution to obtain a description of the rules governing such an account.
The Institution holds shares of the Class registered in its name, as agent for
the customer, on the books of the Institution. A statement with regard to the
customer's shares of the Class is supplied to the customer periodically, and
confirmations of all transactions for the account of the customer are provided
by the Institution to the customer promptly upon request. In addition, the
Institution sends to each customer proxies, periodic reports and other
information with regard to the customer's shares of the Class. The customer's
shares of the Class are fully assignable and subject to encumbrance by the
customer.

8
<PAGE> 74

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.

Federal Reserve wires should be sent as early as possible in order to
facilitate crediting to the shareholder's account. 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 returned to the sending
Institution. An order must specify that it is for the purchase of Shares of the
"Personal Investment Class of the Treasury TaxAdvantage Portfolio," otherwise
any funds received will be returned to the sending Institution.

The Trust reserves the right in its sole discretion to withdraw all or any
part of the offering made by this Prospectus or to reject any purchase order.

REDEMPTION OF SHARES

A shareholder may redeem any or all of its shares of the Class at the net asset
value next determined after receipt of the redemption request in proper form by
the Trust. Redemption requests with respect to the Class may also be
made via AIM LINK--Registered Trademark-- Remote. Normally, the net asset value
per share of the Portfolio will remain constant at $1.00. See "Net Asset Value."
Redemption requests with respect to shares of the Class are normally made
through a customer's Institution.

Payment for redeemed shares of the Class is normally made by Federal
Reserve wire to the commercial bank account designated in the Institution's
Account Application, but may be remitted by check upon request by a shareholder.
If a redemption request is received by the Transfer Agent prior to 3:00 p.m.
Eastern Time on a business day of the Portfolio, the redemption will be effected
at the net asset value next determined on such day and the shares of the Class
to be redeemed will not receive the dividend declared on the effective date of
the redemption. If a redemption request is received by the Transfer Agent after
3:00 p.m. Eastern Time or on other than a business day of the Portfolio, the
redemption will be effected at the net asset value of the Portfolio determined
as of 3:00 p.m. Eastern Time on the next business day of the Portfolio, and the
proceeds of such redemption will normally be wired on the effective day of the
redemption. The Portfolio reserves the right to change the time for which
redemption requests must be submitted to and received by the Transfer Agent for
execution on the same day on any day when the U.S. primary broker-dealer
community is closed for business or trading is restricted due to national
holidays.

9
<PAGE> 75

DIVIDENDS

10
<PAGE> 76

TAXES
FEDERAL TAXATION

STATE AND LOCAL TAXATION

NET ASSET VALUE

11
<PAGE> 77

YIELD INFORMATION

Yield information for the Class can be obtained by calling the Trust at
(800) 877-4744. Yields will fluctuate from time to time and are not necessarily
indicative of future results. Accordingly, the yield information may not provide
a basis for comparison with investments which pay a fixed rate of interest for a
stated period of time. Yield is a function of the type and quality of the
Portfolio's investments, the Portfolio's maturity and the operating expense
ratio of the Class. A SHAREHOLDER'S INVESTMENT IN THE PORTFOLIO IS NOT INSURED
OR GUARANTEED BY THE U.S. GOVERNMENT OR BY ANY INSTITUTION. These factors should
be carefully considered by the investor before making an investment in the
Portfolio.

REPORTS TO SHAREHOLDERS

12
<PAGE> 78

MANAGEMENT OF THE TRUST

BOARD OF TRUSTEES

For a discussion of AIM Management and its subsidiaries' Year 2000
Compliance Project, see "General Information -- Year 2000 Compliance Project."

INVESTMENT ADVISOR

ADMINISTRATIVE SERVICES

FEE WAIVERS

13
<PAGE> 79

DISTRIBUTOR

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
the Class. The address of FMC is 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173. Certain trustees and officers of the Trust are affiliated with FMC
and AIM. The Distribution Agreement provides that FMC has the exclusive right to
distribute shares of the Class either directly or through other broker-dealers.
FMC is the distributor of several of the mutual funds managed or advised by AIM.

DISTRIBUTION PLAN

The Trust has adopted a Master Distribution Plan (the "Plan") pursuant to
Rule 12b-1 under the 1940 Act. The Plan provides that the Trust may compensate
FMC in connection with the distribution of shares of the Class in an amount
equal to 0.75% on an annualized basis of the average daily net assets of the
Portfolio attributable to the Class. Such amounts may be expended when and if
authorized by the Board of Trustees and may be used to finance such
distribution-related services 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
costs of administering the Plan.

Of the compensation paid to FMC under the Plan, a service fee may be paid
to dealers and other financial institutions that provide continuing personal
shareholder services to their customers who purchase and own shares of the
Class, in amounts of up to 0.25% of the average net assets of the Portfolio
attributable to the Class which are attributable to the customers of such
dealers or financial institutions. Payments to dealers and other financial
institutions in excess of such amount and payments retained by FMC would be
characterized as an asset-based sales charge pursuant to the 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 the Class. The Plan
does not obligate the Trust to reimburse FMC for the actual expenses FMC may
incur in fulfilling its obligations under the Plan on behalf of the Class. Thus,
under the Plan, 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.

PORTFOLIO TRANSACTIONS AND BROKERAGE

GENERAL INFORMATION
ORGANIZATION AND DESCRIPTION OF SHARES

15
<PAGE> 81

portfolio or allocated to the respective portfolio based on the liquidation
value of such portfolio. Fractional shares of each portfolio have the same
rights as full shares to the extent of their proportionate interest.

TRANSFER AGENT AND CUSTODIAN

LEGAL COUNSEL

The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania, serves as counsel to the Trust and passes upon certain legal
matters for the Trust.

SHAREHOLDER INQUIRIES

YEAR 2000 COMPLIANCE PROJECT

16
<PAGE> 82

OTHER INFORMATION

17
<PAGE> 83

SHORT-TERM INVESTMENTS TRUST
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-4744

INVESTMENT ADVISOR
A I M ADVISORS, INC.
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(713) 626-1919

DISTRIBUTOR
FUND MANAGEMENT COMPANY
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-4744

AUDITORS
KPMG PEAT MARWICK LLP
700 Louisiana
Houston, Texas 77002

CUSTODIAN
THE BANK OF NEW YORK
90 Washington Street
11th Floor
New York, New York 10286

TRANSFER AGENT
A I M FUND SERVICES, INC.
P.O. Box 4497
Houston, TX 77210-4497

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS IN CONNECTION WITH THE OFFERING
MADE BY THIS PROSPECTUS, AND IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE TRUST
OR THE DISTRIBUTOR. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER IN ANY
JURISDICTION TO ANY PERSON TO WHOM SUCH OFFERING MAY NOT LAWFULLY BE MADE.

SHORT-TERM
INVESTMENTS TRUST

PERSONAL
INVESTMENT CLASS
OF THE
- --------------------------------------------------------------------------------
TREASURY
TAXADVANTAGE
PORTFOLIO PROSPECTUS

DECEMBER 18, 1998

[AIM LOGO APPEARS HERE]
Fund Management Company
<PAGE> 84

PROSPECTUS

PRIVATE INVESTMENT CLASS
OF THE

TREASURY TAXADVANTAGE PORTFOLIO
OF

SHORT-TERM INVESTMENTS TRUST
11 GREENWAY PLAZA, SUITE 100
HOUSTON, TEXAS 77046-1173
(800) 877-7748
---------------------

The Treasury TaxAdvantage Portfolio is a series portfolio of Short-Term
Investments Trust (the "Trust"), an open-end diversified, series, management
investment company. This Prospectus relates solely to the Private Investment
Class of the Treasury TaxAdvantage Portfolio, a class of shares designed to be a
convenient vehicle in which customers of banks, certain broker-dealers and other
financial institutions can invest short-term cash reserves.
---------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION NOR HAS THE SECURITIES AND EXCHANGE COMMISSION PASSED UPON
THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY
IS A CRIMINAL OFFENSE.
---------------------

THIS PROSPECTUS SETS FORTH BASIC INFORMATION THAT A PROSPECTIVE INVESTOR
SHOULD KNOW BEFORE INVESTING IN SHARES OF THE PRIVATE INVESTMENT CLASS OF THE
TREASURY TAXADVANTAGE PORTFOLIO AND SHOULD BE READ AND RETAINED FOR FUTURE
REFERENCE. A STATEMENT OF ADDITIONAL INFORMATION, DATED DECEMBER 18, 1998, HAS
BEEN FILED WITH THE UNITED STATES SECURITIES AND EXCHANGE COMMISSION (THE "SEC")
AND IS HEREBY INCORPORATED BY REFERENCE. FOR A COPY OF THE STATEMENT OF
ADDITIONAL INFORMATION WITHOUT CHARGE, WRITE TO THE ADDRESS ABOVE OR CALL (800)
877-7748. THE SEC MAINTAINS A WEB SITE AT HTTP://WWW.SEC.GOV THAT CONTAINS THE
STATEMENT OF ADDITIONAL INFORMATION, MATERIAL INCORPORATED BY REFERENCE, AND
OTHER INFORMATION REGARDING THE TRUST.

THE TRUST'S SHARES ARE NOT DEPOSITS OR OBLIGATIONS OF, OR GUARANTEED OR
ENDORSED BY, ANY BANK, AND THE TRUST'S SHARES ARE NOT FEDERALLY INSURED OR
GUARANTEED BY THE U.S. GOVERNMENT, THE FEDERAL DEPOSIT INSURANCE CORPORATION,
THE FEDERAL RESERVE BOARD OR ANY OTHER AGENCY. THERE CAN BE NO ASSURANCE THAT
THE TREASURY TAXADVANTAGE PORTFOLIO WILL BE ABLE TO MAINTAIN A STABLE NET ASSET
VALUE OF $1.00 PER SHARE. SHARES OF THE TRUST INVOLVE INVESTMENT RISKS,
INCLUDING THE POSSIBLE LOSS OF PRINCIPAL.

PROSPECTUS DATED: DECEMBER 18, 1998
<PAGE> 85

TABLE OF CONTENTS

<TABLE>
<CAPTION>
PAGE
<S> <C>
SUMMARY........................................... 2
TABLE OF FEES AND EXPENSES........................ 4
FINANCIAL HIGHLIGHTS.............................. 5
SUITABILITY FOR INVESTORS......................... 6
INVESTMENT PROGRAM................................ 6
PURCHASE OF SHARES................................ 8
REDEMPTION OF SHARES.............................. 10
</TABLE>

<TABLE>
<CAPTION>
PAGE
<S> <C>
DIVIDENDS......................................... 11
TAXES............................................. 11
NET ASSET VALUE................................... 12
YIELD INFORMATION................................. 13
REPORTS TO SHAREHOLDERS........................... 13
MANAGEMENT OF THE TRUST........................... 13
GENERAL INFORMATION............................... 16
</TABLE>

SUMMARY

THE PORTFOLIO AND ITS INVESTMENT OBJECTIVE

The Trust is an open-end diversified series management investment company.
This Prospectus relates to the Private Investment Class (the "Class") of the
Treasury TaxAdvantage Portfolio (the "Portfolio"). The Portfolio is a money
market fund which invests in direct obligations of the U.S. Treasury. The
instruments purchased by the Portfolio will have maturities of 397 days or less.
The investment objective of the Portfolio is the maximization of current income
to the extent consistent with the preservation of capital and the maintenance of
liquidity. The Portfolio's investment strategy is intended to enable the
Portfolio to provide its shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions.

Pursuant to separate prospectuses, the Trust also offers other classes of
shares of beneficial interest representing interests in the Portfolio: the Cash
Management Class, the Institutional Class, the Personal Investment Class, the
Reserve Class and the Resource Class. Such classes have different distribution
arrangements and are designed for different types of investors. The Trust also
offers shares of several classes representing interests in each of two other
portfolios, the Government & Agency Portfolio and the Treasury Portfolio,
pursuant to separate prospectuses. The portfolios of the Trust are referred to
collectively as "Portfolios."

INVESTORS IN THE CLASS

The Class is designed to be a convenient vehicle in which customers of
banks, certain broker-dealers and other financial institutions can invest in a
diversified open-end money market fund.

PURCHASE OF SHARES

Shares of the Class that are offered hereby are sold at net asset value.
The minimum initial investment in the Class is $10,000. There is no minimum
amount for subsequent investments. Payment for shares of the Class purchased
must be in funds immediately available to the Trust. See "Purchase of Shares."

REDEMPTION OF SHARES

2
<PAGE> 86

DIVIDENDS

CONSTANT NET ASSET VALUE

INVESTMENT ADVISOR

DISTRIBUTOR AND DISTRIBUTION PLAN

Fund Management Company ("FMC") acts as the exclusive distributor of the
shares of the Class. Pursuant to a plan of distribution adopted by the Trust's
Board of Trustees, the Trust may pay up to 0.50% of the average daily net asset
value of the Portfolio attributable to the Class to FMC as well as to certain
broker-dealers or other financial institutions. Of this amount, up to 0.25% may
be for continuing personal services to shareholders provided by broker-dealers
or institutions and the balance would be deemed an asset-based sales charge. See
"Purchase of Shares" and "Distribution Plan."

SPECIAL RISK CONSIDERATIONS

3
<PAGE> 87
TABLE OF FEES AND EXPENSES

ANNUAL PORTFOLIO OPERATING EXPENSES -- PRIVATE INVESTMENT
CLASS (AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management fees (after fee waivers)**..................... 0.12%
12b-1 fees (after fee waivers)**.......................... 0.25%***
Other expenses:
Custodian fees......................................... 0.01%
Other.................................................. 0.07%
------
Total other expenses.............................. 0.08%
------
Total portfolio operating expenses -- Private Investment
Class**................................................ 0.45%
======
</TABLE>

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

* Beneficial owners of shares of the Class should consider the effect of any
charges imposed by their bank, broker-dealer or financial institution for
various services.
** Had there been no fee waivers, Management fees, 12b-1 fees and Total
portfolio operating expenses would be 0.20%, 0.50% and 0.78%, respectively.
*** It is possible that as a result of Rule 12b-1 fees, long-term shareholders
may pay more than the economic equivalent of the maximum front-end sales
charges permitted under rules of the National Association of Securities
Dealers, Inc. Given the Rule 12b-1 fee of the Class, however, it is
estimated that it would take a substantial number of years for a shareholder
to exceed such maximum front-end sales charges.

EXAMPLE

An investor in the Class would pay the following expenses on a $1,000
investment, assuming (1) a 5% annual return and (2) redemption at the end of
each time period.

<TABLE>
<S> <C>
1 year..................................................... $ 5
3 years.................................................... $14
5 years.................................................... $25
10 years.................................................... $57
</TABLE>

4
<PAGE> 88

voluntary waivers for the Class. Future waivers of fees (if any) may vary from
the figures reflected in the Table of Fees and Expenses. To the extent any
service providers assume additional expenses of the Class, such assumption of
additional expenses will have the effect of lowering the Class's overall expense
ratio and increasing its yield to investors. Beneficial owners of shares of the
Class should also consider the effect of any charges imposed by the institution
maintaining their accounts.

The example in the Table of Fees and Expenses assumes that all dividends
and distributions are reinvested and that the amounts listed under "Annual
Portfolio Operating Expenses -- Private Investment Class" remain the same in the
years shown.

FINANCIAL HIGHLIGHTS

Shown below are the per share data, ratios and supplemental data
(collectively, "data") for the years in the three year period ended August 31,
1998 and the period December 21, 1994 (date sales commenced) through August 31,
1995. The data has been audited by KPMG Peat Marwick LLP, independent auditors,
whose report on the financial statements and the related notes appears in the
Statement of Additional Information.

<TABLE>
<CAPTION>
1998 1997 1996 1995
------- ------- ------- ------
<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 0.04
------- ------- ------- ------
Less distributions:
Dividends from net investment income............ (0.05) (0.05) (0.05) (0.04)
------- ------- ------- ------
Net asset value, end of period.................... $ 1.00 $ 1.00 $ 1.00 $ 1.00
======= ======= ======= ======
Total return...................................... 5.04% 4.87% 4.93% 5.32%(a)
======= ======= ======= ======
Ratios/supplemental data:
Net assets, end of period (000s omitted)........ $31,143 $39,312 $49,978 $5,423
======= ======= ======= ======
Ratio of expenses to average net assets(b)...... 0.45%(c) 0.45% 0.45% 0.45%(a)
======= ======= ======= ======
Ratio of net investment income to average net
assets(d).................................... 4.80%(c) 4.75% 4.72% 5.21%(a)
======= ======= ======= ======
</TABLE>

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

(a) Annualized.

(b) After fee waivers and/or expense reimbursements. Ratios of expenses to
average net assets prior to fee waivers and/or expense reimbursements were
0.78%, 0.74%, 0.85% and 1.02% (annualized) for the periods 1998-1995,
respectively.

(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 4.47%, 4.46%, 4.32% and 4.64% (annualized) for the
periods 1998-1995, respectively.

5
<PAGE> 89

SUITABILITY FOR INVESTORS

Investors in the 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 Class.

INVESTMENT PROGRAM
INVESTMENT OBJECTIVE

INVESTMENT POLICIES

6
<PAGE> 90

if encountered, could cause a reduction in the net asset value of the
Portfolio's shares. Reverse repurchase agreements are considered to be
borrowings under the 1940 Act.

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

The investment policies described above may be changed by the Board of
Trustees without the affirmative vote of a majority of the outstanding shares of
beneficial interest of the Trust.

INVESTMENT RESTRICTIONS

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

7
<PAGE> 91

program may be considered the issuance of senior securities. The Portfolio
will not purchase securities while borrowings in excess of 5% of its total
assets are outstanding.

PURCHASE OF SHARES

8
<PAGE> 92

to the information provided in the Account Application must be made in writing
or by completing a new form and providing it to the Transfer Agent. An investor
must open an account in the shares of the Class through an Institution in
accordance with procedures established by such Institution. Each Institution
separately determines the rules applicable to accounts in the shares of the
Class opened with it, including minimum initial and subsequent investment
requirements and the procedures to be followed by investors to effect purchases
of shares of the Class. The minimum initial investment is $10,000, and there is
no minimum amount of subsequent purchases of shares of the Class by an
Institution on behalf of its customers. An investor who proposes to open a
Portfolio account with an Institution should consult with a representative of
such Institution to obtain a description of the rules governing such an account.
The Institution holds shares of the Class registered in its name, as agent for
the customer, on the books of the Institution. A statement with regard to the
customer's shares of the Class is supplied to the customer periodically, and
confirmations of all transactions for the account of the customer are provided
by the Institution to the customer promptly upon request. In addition, the
Institution sends to each customer proxies, periodic reports and other
information with regard to the customer's shares of the Class. The customer's
shares of the Class are fully assignable and subject to encumbrance by the
customer.

Any request for correction to a transaction of Portfolio shares must be
submitted in writing to the Transfer Agent. The Transfer Agent 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.

Federal Reserve wires should be sent as early as possible in order to
facilitate crediting to the shareholder's account. 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 returned to the sending
Institution. An order must specify that it is for the purchase of Shares of the
"Private Investment Class of the Treasury TaxAdvantage Portfolio," otherwise any
funds received will be returned to the sending Institution.

The Trust reserves the right in its sole discretion to withdraw all or any
part of the offering made by this Prospectus or to reject any purchase order.
9
<PAGE> 93

REDEMPTION OF SHARES

10
<PAGE> 94

DIVIDENDS

TAXES
FEDERAL TAXATION

STATE AND LOCAL TAXATION

NET ASSET VALUE

12
<PAGE> 96

YIELD INFORMATION

Yield information for the Class can be obtained by calling the Trust at
(800) 877-7748. Yields will fluctuate from time to time and are not necessarily
indicative of future results. Accordingly, the yield information may not provide
a basis for comparison with investments which pay a fixed rate of interest for a
stated period of time. Yield is a function of the type and quality of the
Portfolio's investments, the Portfolio's maturity and the operating expense
ratio of the Class. A SHAREHOLDER'S INVESTMENT IN THE PORTFOLIO IS NOT INSURED
OR GUARANTEED BY THE U.S. GOVERNMENT OR BY ANY INSTITUTION. These factors should
be carefully considered by the investor before making an investment in the
Portfolio.

For the seven-day period ended August 31, 1998, the current yield and the
effective yield of the Class (which assumes the reinvestment of dividends for a
365-day year and a return for the entire year equal to the average annualized
current yield for the period) were 4.74% and 4.85%, respectively. These
performance numbers are quoted for illustration purposes only. The performance
numbers for any other seven-day period may be substantially different from those
quoted above.

REPORTS TO SHAREHOLDERS

MANAGEMENT OF THE TRUST
BOARD OF TRUSTEES

For a discussion of AIM Management and its subsidiaries' Year 2000
Compliance Project, see "General Information -- Year 2000 Compliance Project."

13
<PAGE> 97

INVESTMENT ADVISOR

ADMINISTRATIVE SERVICES

FEE WAIVERS

DISTRIBUTOR

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
the Class. The address of FMC is 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173. Certain trustees and officers of the Trust are affiliated with FMC
and AIM. The Distribution Agreement provides that FMC has the exclusive right to
distribute shares of the Class either directly or through other broker-dealers.
FMC is the distributor of several of the mutual funds managed or advised by AIM.

14
<PAGE> 98

sales of the shares of the Class 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. The Plan provides that the Trust may compensate
FMC in connection with the distribution of shares of the Class in an amount
equal to 0.50% on an annualized basis of the average daily net assets of the
Portfolio attributable to the Class. Such amounts may be expended when and if
authorized by the Board of Trustees and may be used to finance such
distribution-related services 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
costs of administering the Plan.

Of the compensation paid to FMC under the Plan, a service fee may be paid
to dealers and other financial institutions that provide continuing personal
shareholder services to their customers who purchase and own shares of the
Class, in amounts of up to 0.25% of the average net assets of the Portfolio
attributable to the Class which are attributable to the customers of such
dealers or financial institutions. Payments to dealers and other financial
institutions in excess of such amount and payments retained by FMC would be
characterized as an asset-based sales charge pursuant to the 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 the Class. The Plan
does not obligate the Trust to reimburse FMC for the actual expenses FMC may
incur in fulfilling its obligations under the Plan on behalf of the Class. Thus,
under the Plan, 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.

PORTFOLIO TRANSACTIONS AND BROKERAGE

GENERAL INFORMATION
ORGANIZATION AND DESCRIPTION OF SHARES

16
<PAGE> 100

TRANSFER AGENT AND CUSTODIAN

The Bank of New York, 90 Washington Street, 11th Floor, New York, New York
10286, acts as custodian for the portfolio securities and cash of the Portfolio.
A I M Fund Services, Inc., P.O. Box 4497, Houston, Texas 77210-4479, acts as
transfer agent for the shares of the Portfolio.

LEGAL COUNSEL

The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania, serves as counsel to the Trust and passes upon certain legal
matters for the Trust.

SHAREHOLDER INQUIRIES

YEAR 2000 COMPLIANCE PROJECT

OTHER INFORMATION

17
<PAGE> 101

[THIS PAGE INTENTIONALLY LEFT BLANK]
<PAGE> 102
SHORT-TERM INVESTMENTS TRUST
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-7748

INVESTMENT ADVISOR
A I M ADVISORS, INC.
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(713) 626-1919

DISTRIBUTOR
FUND MANAGEMENT COMPANY
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 877-7748

AUDITORS
KPMG PEAT MARWICK LLP
700 Louisiana
Houston, Texas 77002

CUSTODIAN
THE BANK OF NEW YORK
90 Washington Street
11th Floor
New York, New York 10286

TRANSFER AGENT
A I M FUND SERVICES, INC.
P.O. Box 4497
Houston, Texas 77210-4497

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS IN CONNECTION WITH THE OFFERING
MADE BY THIS PROSPECTUS, AND IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE TRUST
OR THE DISTRIBUTOR. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER IN ANY
JURISDICTION TO ANY PERSON TO WHOM SUCH OFFERING MAY NOT LAWFULLY BE MADE.

SHORT-TERM
INVESTMENTS TRUST

PRIVATE
INVESTMENT CLASS
OF THE
- ------------------------------------------------------
TREASURY
TAXADVANTAGE
PORTFOLIO PROSPECTUS

DECEMBER 18, 1998

[AIM LOGO APPEARS HERE]
Fund Management Company
<PAGE> 103
SHORT-TERM
INVESTMENTS TRUST

Prospectus
- --------------------------------------------------------------------------------

THIS PROSPECTUS SETS FORTH BASIC INFORMATION THAT
A PROSPECTIVE INVESTOR SHOULD KNOW BEFORE INVESTING IN
SHARES OF THE RESERVE CLASS OF THE TREASURY
TAXADVANTAGE PORTFOLIO AND SHOULD BE READ AND RETAINED
FOR FUTURE REFERENCE. A STATEMENT OF ADDITIONAL
INFORMATION, DATED DECEMBER 18, 1998, HAS BEEN FILED
WITH THE UNITED STATES SECURITIES AND EXCHANGE
COMMISSION (THE "SEC") AND IS HEREBY INCORPORATED BY
REFERENCE. FOR A COPY OF THE STATEMENT OF ADDITIONAL
INFORMATION WITHOUT CHARGE, WRITE TO THE ADDRESS ABOVE
OR CALL (800) 467-8792. THE SEC MAINTAINS A WEB SITE AT
HTTP://WWW.SEC.GOV THAT CONTAINS THE STATEMENT OF
ADDITIONAL INFORMATION, MATERIAL INCORPORATED BY
REFERENCE, AND OTHER INFORMATION REGARDING THE TRUST.

[AIM LOGO APPEARS HERE]
Fund Management Company

11 Greenway Plaza
Suite 100
Houston, Texas 77046-1173
(800) 467-8792
<PAGE> 104

SUMMARY

THE PORTFOLIO AND ITS INVESTMENT OBJECTIVE

The Trust is an open-end diversified series management investment company.
This Prospectus relates to the Reserve Class (the "Class") of the Treasury
TaxAdvantage Portfolio (the "Portfolio"). The Portfolio is a money market fund
which invests in direct obligations of the U.S. Treasury. The instruments
purchased by the Portfolio will have maturities of 397 days or less. The
investment objective of the Portfolio is the maximization of current income to
the extent consistent with the preservation of capital and the maintenance of
liquidity. The Portfolio's investment strategy is intended to enable the
Portfolio to provide its shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions.

Pursuant to separate prospectuses, the Trust also offers other classes of
shares of beneficial interest representing interests in the Portfolio: the Cash
Management Class, the Institutional Class, the Personal Investment Class, the
Private Investment Class and the Resource Class. Such classes have different
distribution arrangements and are designed for different types of investors. The
Trust also offers shares of several classes representing interests in each of
two other portfolios, the Government & Agency Portfolio and the Treasury
Portfolio, pursuant to separate prospectuses. The portfolios of the Trust are
referred to collectively as "Portfolios."

INVESTORS IN THE CLASS

The Class is designed to be a convenient vehicle in which customers of
banks, certain broker-dealers and other financial institutions can invest in a
diversified open-end money market fund.

PURCHASE OF SHARES

REDEMPTION OF SHARES

DIVIDENDS

CONSTANT NET ASSET VALUE

2
<PAGE> 105

INVESTMENT ADVISOR

DISTRIBUTOR AND DISTRIBUTION PLAN

Fund Management Company ("FMC") acts as the exclusive distributor of the
shares of the Class. Pursuant to a plan of distribution adopted by the Trust's
Board of Trustees, the Trust may pay up to 1.00% of the average daily net asset
value of the Portfolio attributable to the Class to FMC as well as to certain
broker-dealers or other financial institutions. Of this amount, up to 0.25% may
be for continuing personal services to shareholders provided by broker-dealers
or institutions and the balance would be deemed an asset-based sales charge. See
"Purchase of Shares" and "Distribution Plan."

SPECIAL RISK CONSIDERATIONS

3
<PAGE> 106

TABLE OF FEES AND EXPENSES

ANNUAL PORTFOLIO OPERATING EXPENSES -- RESERVE CLASS
(AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management fees (after fee waivers)**..................... 0.12%
12b-1 fees (after fee waivers)**.......................... 0.80%***
Other expenses (estimated):
Custodian fees......................................... 0.01%
Other.................................................. 0.07%
------
Total other expenses.............................. 0.08%
------
Total portfolio operating expenses -- Reserve Class**..... 1.00%
======
</TABLE>

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

* Beneficial owners of shares of the Class should consider the effect of any
charges imposed by their bank, broker-dealer or financial institution for
various services.
** Had there been no fee waivers, Management fees, 12b-1 fees and Total
portfolio operating expenses would be 0.20%, 1.00% and 1.28%, respectively.
*** It is possible that as a result of Rule 12b-1 fees, long-term shareholders
may pay more than the economic equivalent of the maximum front-end sales
charges permitted under rules of the National Association of Securities
Dealers, Inc. Given the Rule 12b-1 fee of the Class, however, it is
estimated that it would take a substantial number of years for a shareholder
to exceed such maximum front-end sales charges.

EXAMPLE

An investor in the Class would pay the following expenses on a $1,000
investment, assuming (1) a 5% annual return and (2) redemption at the end of
each time period.

<TABLE>
<S> <C>
1 year...................................................... $10
3 years..................................................... $32
</TABLE>

The Table of Fees and Expenses is designed to assist an investor in
understanding the various costs and expenses that an investor in the Class will
bear directly or indirectly. (For more complete descriptions of the various
costs and expenses, see "Management of the Trust" below.) The "Total portfolio
operating expenses -- Reserve Class" figure is based upon costs and the
estimated size of the Class and fees to be charged for the current fiscal
period. The "Other expenses" and "12b-1 fees" figures are based upon estimated
costs and the estimated size of the Class and the Portfolio and estimated fees
to be charged for the current fiscal period. Thus, actual expenses may be
greater or less than such estimates. The Table of Fees and Expenses reflects
voluntary waivers for the Class. Future waivers of fees (if any) may vary from
the figures reflected in the Table of Fees and Expenses. To the extent any
service providers assume additional expenses of the Class, such assumption of
additional expenses will have the effect of lowering the Class's overall expense
ratio and increasing its yield to investors. Beneficial owners of shares of the
Class should also consider the effect of any charges imposed by the institution
maintaining their accounts.

4
<PAGE> 107

SUITABILITY FOR INVESTORS

Investors in the 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 Class.

INVESTMENT PROGRAM

INVESTMENT OBJECTIVE

INVESTMENT POLICIES

5
<PAGE> 108

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 under the 1940
Act.

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

The investment policies described above may be changed by the Board of
Trustees without the affirmative vote of a majority of the outstanding shares of
beneficial interest of the Trust.

INVESTMENT RESTRICTIONS

6
<PAGE> 109

The Portfolio will not purchase securities while borrowings in
excess of 5% of its total assets are outstanding.

PURCHASE OF SHARES

7
<PAGE> 110

investors to effect purchases of shares of the Class. The minimum initial
investment is $1,000, and there is no minimum amount of subsequent purchases of
shares of the Class by an Institution on behalf of its customers. An investor
who proposes to open a Portfolio account with an Institution should consult with
a representative of such Institution to obtain a description of the rules
governing such an account. The Institution holds shares of the Class registered
in its name, as agent for the customer, on the books of the Institution. A
statement with regard to the customer's shares of the Class is supplied to the
customer periodically, and confirmations of all transactions for the account of
the customer are provided by the Institution to the customer promptly upon
request. In addition, the Institution sends to each customer proxies, periodic
reports and other information with regard to the customer's shares of the Class.
The customer's shares of the Class are fully assignable and subject to
encumbrance by the customer.

Federal Reserve wires should be sent as early as possible in order to
facilitate crediting to the shareholder's account. 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 returned to the sending
Institution. An order must specify that it is for the purchase of Shares of the
"Reserve Class of the Treasury TaxAdvantage Portfolio," otherwise any funds
received will be returned to the sending Institution.

The Trust reserves the right in its sole discretion to withdraw all or any
part of the offering made by this Prospectus or to reject any purchase order.

REDEMPTION OF SHARES

8
<PAGE> 111

DIVIDENDS

9
<PAGE> 112

be made in writing by the Institution to the Transfer Agent at P.O. Box 4497,
Houston, TX 77210-4497, and will become effective with dividends paid after its
receipt by the Transfer Agent. If a shareholder redeems all the shares of the
Class in its 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.

TAXES

FEDERAL TAXATION

STATE AND LOCAL TAXATION

10
<PAGE> 113

after-tax return comparable to or higher than that obtained from other money
market funds. Shareholders should consult their own tax advisors concerning the
tax impact of their investment in the Portfolio and the application of state,
local or foreign taxes.

NET ASSET VALUE

YIELD INFORMATION

Yield information for the Class can be obtained by calling the Trust at
(800) 467-8792. Yields will fluctuate from time to time and are not necessarily
indicative of future results. Accordingly, the yield information may not provide
a basis for comparison with investments which pay a fixed rate of interest for a
stated period of time. Yield is a function of the type and quality of the
Portfolio's investments, the Portfolio's maturity and the operating expense
ratio of the Class. A SHAREHOLDER'S INVESTMENT IN THE PORTFOLIO IS NOT INSURED
OR GUARANTEED BY THE U.S. GOVERNMENT OR BY ANY INSTITUTION. These factors should
be carefully considered by the investor before making an investment in the
Portfolio.

REPORTS TO SHAREHOLDERS

11
<PAGE> 114

MANAGEMENT OF THE TRUST

BOARD OF TRUSTEES

For a discussion of AIM Management and its subsidiaries' Year 2000
Compliance Project, see "General Information -- Year 2000 Compliance Project."

INVESTMENT ADVISOR

ADMINISTRATIVE SERVICES

FEE WAIVERS

12
<PAGE> 115

DISTRIBUTOR

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
the Class. The address of FMC is 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173. Certain trustees and officers of the Trust are affiliated with FMC
and AIM. The Distribution Agreement provides that FMC has the exclusive right to
distribute shares of the Class either directly or through other broker-dealers.
FMC is the distributor of several of the mutual funds managed or advised by AIM.

DISTRIBUTION PLAN

The Trust has adopted a Master Distribution Plan (the "Plan") pursuant to
Rule 12b-1 under the 1940 Act. The Plan provides that the Trust may compensate
FMC in connection with the distribution of shares of the Class in an amount
equal to 1.00% on an annualized basis of the average daily net assets of the
Portfolio attributable to the Class. Such amounts may be expended when and if
authorized by the Board of Trustees and may be used to finance such
distribution-related services 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
costs of administering the Plan.

Of the compensation paid to FMC under the Plan, a service fee may be paid
to dealers and other financial institutions that provide continuing personal
shareholder services to their customers who purchase and own shares of the
Class, in amounts of up to 0.25% of the average net assets of the Portfolio
attributable to the Class which are attributable to the customers of such
dealers or financial institutions. Payments to dealers and other financial
institutions in excess of such amount and payments retained by FMC would be
characterized as an asset-based sales charge pursuant to the 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 the Class. The Plan
does not obligate the Trust to reimburse FMC for the actual expenses FMC may
incur in fulfilling its obligations under the Plan on behalf of the Class. Thus,
under the Plan, 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.

13
<PAGE> 116

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.

PORTFOLIO TRANSACTIONS AND BROKERAGE

GENERAL INFORMATION

ORGANIZATION AND DESCRIPTION OF SHARES

14
<PAGE> 117

shareholders for the sole purpose of considering removal of a trustee shall be
called at the request of the holders of 10% or more of the Trust's outstanding
shares.

TRANSFER AGENT AND CUSTODIAN

The Bank of New York, 90 Washington Street, 11th Floor, New York, New York
10286, acts as custodian for the portfolio securities and cash of the Portfolio.
A I M Fund Services, Inc., P.O. Box 4497, Houston, Texas 77210-4492, acts as
transfer agent for the shares of the Portfolio.

LEGAL COUNSEL

The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania, serves as counsel to the Trust and passes upon certain legal
matters for the Trust.

SHAREHOLDER INQUIRIES

YEAR 2000 COMPLIANCE PROJECT

OTHER INFORMATION

15
<PAGE> 118
================================================================================

SHORT-TERM INVESTMENTS TRUST
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 467-8792

INVESTMENT ADVISOR
A I M ADVISORS, INC.
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(713) 626-1919

DISTRIBUTOR
FUND MANAGEMENT COMPANY
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 467-8792

AUDITORS
KPMG PEAT MARWICK LLP
700 Louisiana
Houston, Texas 77002

CUSTODIAN
THE BANK OF NEW YORK
90 Washington Street,
11th Floor
New York, New York 10286

TRANSFER AGENT
A I M FUND SERVICES, INC.
P.O. Box 4497
Houston, TX 77210-4497

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS IN CONNECTION WITH THE OFFERING
MADE BY THIS PROSPECTUS, AND IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE TRUST
OR THE DISTRIBUTOR. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER IN ANY
JURISDICTION TO ANY PERSON TO WHOM SUCH OFFERING MAY NOT LAWFULLY BE MADE.

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

PROSPECTUS

December 18, 1998

SHORT-TERM
INVESTMENTS TRUST

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

TREASURY TAXADVANTAGE
PORTFOLIO

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

RESERVE CLASS

TABLE OF CONTENTS

================================================================================
<PAGE> 119
SHORT-TERM
INVESTMENTS TRUST

Prospectus
- --------------------------------------------------------------------------------

THIS PROSPECTUS SETS FORTH BASIC INFORMATION THAT
A PROSPECTIVE INVESTOR SHOULD KNOW BEFORE INVESTING IN
SHARES OF THE RESOURCE CLASS OF THE TREASURY
TAXADVANTAGE PORTFOLIO AND SHOULD BE READ AND RETAINED
FOR FUTURE REFERENCE. A STATEMENT OF ADDITIONAL
INFORMATION, DATED DECEMBER 18, 1998, HAS BEEN FILED
WITH THE UNITED STATES SECURITIES AND EXCHANGE
COMMISSION (THE "SEC") AND IS HEREBY INCORPORATED BY
REFERENCE. FOR A COPY OF THE STATEMENT OF ADDITIONAL
INFORMATION WITHOUT CHARGE, WRITE TO THE ADDRESS ABOVE
OR CALL (800) 825-6858. THE SEC MAINTAINS A WEB SITE AT
HTTP://WWW.SEC.GOV THAT CONTAINS THE STATEMENT OF
ADDITIONAL INFORMATION, MATERIAL INCORPORATED BY
REFERENCE, AND OTHER INFORMATION REGARDING THE TRUST.

THE TRUST'S SHARES ARE NOT DEPOSITS OR OBLIGATIONS OF,
OR GUARANTEED OR ENDORSED BY, ANY BANK, AND THE TRUST'S
SHARES ARE NOT FEDERALLY INSURED OR GUARANTEED BY THE
U.S. GOVERNMENT, THE FEDERAL DEPOSIT INSURANCE
CORPORATION, THE FEDERAL RESERVE BOARD OR ANY OTHER
AGENCY. THERE CAN BE NO ASSURANCE THAT THE TREASURY
TAXADVANTAGE PORTFOLIO WILL BE ABLE TO MAINTAIN A
STABLE NET ASSET VALUE OF $1.00 PER SHARE. SHARES OF
THE TRUST INVOLVE INVESTMENT RISKS, INCLUDING THE
POSSIBLE LOSS OF PRINCIPAL.

[AIM LOGO APPEARS HERE]
Fund Management Company

11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 825-6858
<PAGE> 120

SUMMARY

THE PORTFOLIO AND ITS INVESTMENT OBJECTIVE

The Trust is an open-end diversified series management investment company.
This Prospectus relates to the Resource Class (the "Class") of the Treasury
TaxAdvantage Portfolio (the "Portfolio"). The Portfolio is a money market fund
which invests in direct obligations of the U.S. Treasury. The instruments
purchased by the Portfolio will have maturities of 397 days or less. The
investment objective of the Portfolio is the maximization of current income to
the extent consistent with the preservation of capital and the maintenance of
liquidity. The Portfolio's investment strategy is intended to enable the
Portfolio to provide its shareholders with dividends that are exempt from state
and local income taxation in certain jurisdictions.

Pursuant to separate prospectuses, the Trust also offers other classes of
shares of beneficial interest representing interests in the Portfolio: the Cash
Management Class, the Institutional Class, the Personal Investment Class, the
Private Investment Class and the Reserve Class. Such classes have different
distribution arrangements and are designed for different types of investors. The
Trust also offers shares of several classes representing interests in each of
two other portfolios, the Government & Agency Portfolio and the Treasury
Portfolio, pursuant to separate prospectuses. The portfolios of the Trust are
referred to collectively as "Portfolios."

INVESTORS IN THE CLASS

The Class is designed to be a convenient vehicle in which customers of
banks, certain broker-dealers and other financial institutions can invest in a
diversified open-end money market fund.

PURCHASE OF SHARES

REDEMPTION OF SHARES

DIVIDENDS

CONSTANT NET ASSET VALUE

2
<PAGE> 121

INVESTMENT ADVISOR

DISTRIBUTOR AND DISTRIBUTION PLAN

SPECIAL RISK CONSIDERATIONS

3
<PAGE> 122

TABLE OF FEES AND EXPENSES

ANNUAL PORTFOLIO OPERATING EXPENSES -- RESOURCE CLASS
(AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management fees (after fee waivers)**..................... 0.12%
12b-1 fees (after fee waivers)**.......................... 0.16%
Other expenses (estimated):
Custodian fees......................................... 0.01%
Other.................................................. 0.07%
------
Total other expenses.............................. 0.08%
------
Total portfolio operating expenses -- Resource Class**.... 0.36%
======
</TABLE>

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

EXAMPLE

An investor in the Class would pay the following expenses on a $1,000
investment, assuming (1) a 5% annual return and (2) redemption at the end of
each time period.

<TABLE>
<S> <C>
1 year..................................................... $ 4
3 years.................................................... $12
</TABLE>

The Table of Fees and Expenses is designed to assist an investor in
understanding the various costs and expenses that an investor in the Class will
bear directly or indirectly. (For more complete descriptions of the various
costs and expenses, see "Management of the Trust" below.) The "Total portfolio
operating expenses -- Resource Class" figure is based upon costs and the
estimated size of the Class and fees to be charged for the current fiscal
period. The "Other Expenses" and "12b-1 fees" figures are based upon estimated
costs and the estimated size of the Class and the Portfolio and estimated fees
to be charged for the current fiscal period. Thus, actual expenses may be
greater or less than such estimates. The Table of Fees and Expenses reflects
voluntary waivers for the Class. Future waivers of fees (if any) may vary from
the figures reflected in the Table of Fees and Expenses. To the extent any
service providers assume additional expenses of the Class, such assumption of
additional expenses will have the effect of lowering the Class's overall expense
ratio and increasing its yield to investors. Beneficial owners of shares of the
Class should also consider the effect of any charges imposed by the institution
maintaining their accounts.

The example in the Table of Fees and Expenses assumes that all dividends
and distributions are reinvested and that the amounts listed under "Annual
Portfolio Operating Expenses -- Resource Class" remain the same in the years
shown.

4
<PAGE> 123

SUITABILITY FOR INVESTORS

Investors in the 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 Class.

INVESTMENT PROGRAM

INVESTMENT OBJECTIVE

INVESTMENT POLICIES

5
<PAGE> 124

encountered, could cause a reduction in the net asset value of the Portfolio's
shares. Reverse repurchase agreements are considered to be borrowings under the
1940 Act.

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

The investment policies described above may be changed by the Board of
Trustees without the affirmative vote of a majority of the outstanding shares of
beneficial interest of the Trust.

INVESTMENT RESTRICTIONS

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PURCHASE OF SHARES

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An investor who proposes to open a Portfolio account with an Institution should
consult with a representative of such Institution to obtain a description of the
rules governing such an account. The Institution holds shares of the Class
registered in its name, as agent for the customer, on the books of the
Institution. A statement with regard to the customer's shares of the Class is
supplied to the customer periodically, and confirmations of all transactions for
the account of the customer are provided by the Institution to the customer
promptly upon request. In addition, the Institution sends to each customer
proxies, periodic reports and other information with regard to the customer's
shares of the Class. The customer's shares of the Class are fully assignable and
subject to encumbrance by the customer.

Federal Reserve wires should be sent as early as possible in order to
facilitate crediting to the shareholder's account. 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 returned to the sending
Institution. An order must specify that it is for the purchase of Shares of the
"Resource Class of the Treasury TaxAdvantage Portfolio," otherwise any funds
received will be returned to the sending Institution.

The Trust reserves the right in its sole discretion to withdraw all or any
part of the offering made by this Prospectus or to reject any purchase order.

REDEMPTION OF SHARES

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DIVIDENDS

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the shares of the Class in its 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.

TAXES

FEDERAL TAXATION

STATE AND LOCAL TAXATION

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should consult their own tax advisors concerning the tax impact of their
investment in the Portfolio and the application of state, local or foreign
taxes.

NET ASSET VALUE

YIELD INFORMATION

Yield information for the Class can be obtained by calling the Trust at
(800) 825-6858. Yields will fluctuate from time to time and are not necessarily
indicative of future results. Accordingly, the yield information may not provide
a basis for comparison with investments which pay a fixed rate of interest for a
stated period of time. Yield is a function of the type and quality of the
Portfolio's investments, the Portfolio's maturity and the operating expense
ratio of the Class. A SHAREHOLDER'S INVESTMENT IN THE PORTFOLIO IS NOT INSURED
OR GUARANTEED BY THE U.S. GOVERNMENT OR BY ANY INSTITUTION. These factors should
be carefully considered by the investor before making an investment in the
Portfolio.

REPORTS TO SHAREHOLDERS

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MANAGEMENT OF THE TRUST

BOARD OF TRUSTEES

For a discussion of AIM Management and its subsidiaries' Year 2000
Compliance Project, see "General Information -- Year 2000 Compliance Project."

INVESTMENT ADVISOR

ADMINISTRATIVE SERVICES

FEE WAIVERS

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DISTRIBUTOR

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
the Class. The address of FMC is 11 Greenway Plaza, Suite 100, Houston, Texas
77046-1173. Certain trustees and officers of the Trust are affiliated with FMC
and AIM. The Distribution Agreement provides that FMC has the exclusive right to
distribute shares of the Class either directly or through other broker-dealers.
FMC is the distributor of several of the mutual funds managed or advised by AIM.

DISTRIBUTION PLAN

The Trust has adopted a Master Distribution Plan (the "Plan") pursuant to
Rule 12b-1 under the 1940 Act. The Plan provides that the Trust may compensate
FMC in connection with the distribution of shares of the Class in an amount
equal to 0.20% on an annualized basis of the average daily net assets of the
Portfolio attributable to the Class. Such amounts may be expended when and if
authorized by the Board of Trustees and may be used to finance such
distribution-related services 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
costs of administering the Plan.

Of the compensation paid to FMC under the Plan, a service fee may be paid
to dealers and other financial institutions that provide continuing personal
shareholder services to their customers who purchase and own shares of the
Class, in amounts of up to 0.20% of the average net assets of the Portfolio
attributable to the Class which are attributable to the customers of such
dealers or financial institutions. Payments retained by FMC would be
characterized as an asset-based sales charge pursuant to the 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 the Class. The Plan
does not obligate the Trust to reimburse FMC for the actual expenses FMC may
incur in fulfilling its obligations under the Plan on behalf of the Class. Thus,
under the Plan, 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.

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PORTFOLIO TRANSACTIONS AND BROKERAGE

GENERAL INFORMATION

ORGANIZATION AND DESCRIPTION OF SHARES

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shareholders for the sole purpose of considering removal of a trustee shall be
called at the request of the holders of 10% or more of the Trust's outstanding
shares.

TRANSFER AGENT AND CUSTODIAN

LEGAL COUNSEL

The law firm of Ballard Spahr Andrews & Ingersoll, LLP, Philadelphia,
Pennsylvania, serves as counsel to the Trust and passes upon certain legal
matters for the Trust.

SHAREHOLDER INQUIRIES

YEAR 2000 COMPLIANCE PROJECT

OTHER INFORMATION

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

SHORT-TERM INVESTMENTS TRUST
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 825-6858

INVESTMENT ADVISOR
A I M ADVISORS, INC.
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(713) 626-1919

DISTRIBUTOR
FUND MANAGEMENT COMPANY
11 Greenway Plaza, Suite 100
Houston, Texas 77046-1173
(800) 825-6858

AUDITORS
KPMG PEAT MARWICK LLP
700 Louisiana
Houston, Texas 77002

CUSTODIAN
THE BANK OF NEW YORK
90 Washington Street
11th Floor
New York, New York 10286

TRANSFER AGENT
A I M FUND SERVICES, INC.
P.O. Box 4497
Houston, TX 77210-4497

NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS IN CONNECTION WITH THE OFFERING
MADE BY THIS PROSPECTUS, AND IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE TRUST
OR THE DISTRIBUTOR. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER IN ANY
JURISDICTION TO ANY PERSON TO WHOM SUCH OFFERING MAY NOT LAWFULLY BE MADE.

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PROSPECTUS

December 18, 1998

SHORT-TERM
INVESTMENTS TRUST

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TREASURY
TAXADVANTAGE
PORTFOLIO

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RESOURCE CLASS

TABLE OF CONTENTS

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