SEI LIQUID ASSET TRUST, 485BPOS, 1999-10-28

SEI LIQUID ASSET TRUST
485BPOS, 1999-10-28

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<PAGE>

AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON OCTOBER 28, 1999

FILE NO. 2-73428
FILE NO. 811-3231
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

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

FORM N-1A

<TABLE>
<S> <C> <C>
REGISTRATION STATEMENT UNDER THE
SECURITIES ACT OF 1933 / /
POST-EFFECTIVE AMENDMENT NO. 24 /X/
AND
REGISTRATION STATEMENT UNDER THE
INVESTMENT COMPANY ACT OF 1940 / /
AMENDMENT NO. 24 /X/
</TABLE>

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

SEI LIQUID ASSET TRUST
(Exact Name of Registrant as Specified in Charter)

C/O CT CORPORATION
2 Oliver Street
Boston, Massachusetts 02109
(Address of Principal Executive Offices) (Zip Code)
Registrant's Telephone Number, including Area Code: (800) 342-5734

EDWARD D. LOUGHLIN
c/o SEI Investments Company
Oaks, Pennsylvania 19456
(Name and Address of Agent for Service)

COPIES TO:

<TABLE>
<S> <C>
Richard W. Grant, Esq. John H. Grady, Jr., Esq.
Morgan, Lewis & Bockius LLP Morgan, Lewis & Bockius LLP
1701 Market Street 1701 Market Street
Philadelphia, Pennsylvania 19103 Philadelphia, Pennsylvania 19103
</TABLE>

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

Title of Securities Being Registered . . . Units of Beneficial Interest

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

<TABLE>
<C> <S>
/X/ immediately upon filing pursuant to paragraph (b)
/ / on [date] pursuant to paragraph (b)
/ / 60 days after filing pursuant to paragraph (a)
/ / on October 28, 1999 pursuant to paragraph (a) of Rule 485
</TABLE>

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- --------------------------------------------------------------------------------
<PAGE>
SEI
LIQUID
ASSET
TRUST
CLASS A SHARES

PROSPECTUS
OCTOBER 31, 1999

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

TREASURY SECURITIES FUND
GOVERNMENT SECURITIES FUND
PRIME OBLIGATION FUND
---------------------------------------------------------

ADVISER
WELLINGTON MANAGEMENT COMPANY, LLP

THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED ANY
FUND SHARES OR DETERMINED WHETHER THIS PROSPECTUS IS ACCURATE OR
COMPLETE.
IT IS A CRIME FOR ANYONE TO TELL YOU OTHERWISE.
<PAGE>
SEI Liquid
Asset Trust
ABOUT THIS PROSPECTUS
- ------------------------------------------------------------------------

SEI Liquid Asset Trust is a mutual fund family that offers different classes of
shares in separate investment portfolios (Funds). The Funds have individual
investment goals and strategies, and are designed primarily for institutional
investors. This prospectus gives you important information about the Class A
Shares of the Funds that you should know before investing. Please read this
prospectus and keep it for future reference.

THIS PROSPECTUS HAS BEEN ARRANGED INTO DIFFERENT SECTIONS SO THAT YOU CAN EASILY
REVIEW THIS IMPORTANT INFORMATION. ON THE NEXT PAGE, THERE IS SOME GENERAL
INFORMATION YOU SHOULD KNOW ABOUT RISK AND RETURN WHICH IS COMMON TO EACH FUND.
FOR MORE DETAILED INFORMATION ABOUT THE FUNDS PLEASE SEE:

TREASURY SECURITIES FUND.............................................4

GOVERNMENT SECURITIES FUND...........................................6

PRIME OBLIGATION FUND................................................8

THE FUNDS' OTHER INVESTMENTS........................................10

THE INVESTMENT ADVISER..............................................10

PURCHASING AND SELLING FUND SHARES..................................10

DIVIDENDS AND DISTRIBUTIONS.........................................12

TAXES...............................................................12

FINANCIAL HIGHLIGHTS................................................13

HOW TO OBTAIN MORE INFORMATION ABOUT SEI LIQUID ASSET TRUST.......Back
Cover
<PAGE>
PROSPECTUS 3

RISK/RETURN INFORMATION COMMON TO THE FUNDS

Each Fund is a mutual fund. A mutual fund pools shareholders' money and, using
professional investment managers, invests it in securities.

Each Fund has its own investment goal and strategies for reaching that goal.
Each Fund's assets are managed under the direction of its Adviser. The Adviser
invests each Fund's assets in a way it believes will help each Fund achieve its
goal. Still, investing in the Funds involves risk, and there is no guarantee
that the Funds will achieve their goal. In fact, no matter how good a job the
Adviser does, you could lose money on your investment in the Funds, just as you
could with other investments. A Fund share is not a bank deposit and it is not
insured or guaranteed by the FDIC or any other government agency.

ALTHOUGH EACH FUND IS MANAGED TO MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00,
IT IS POSSIBLE TO LOSE MONEY BY INVESTING IN THE FUNDS.

- --------------------------------------------------------------------------------
YEAR 2000 RISKS

Like other mutual funds (and most organizations around the world), the Funds
could be affected by computer problems related to the transition to the year
2000. While no one knows if these problems will have any impact on the Funds or
on the financial markets in general, each Fund is taking steps to protect Fund
investors. These include efforts to ensure that each Fund's own systems are
prepared to make the transition to the year 2000, and to determine that the
problem will not affect the systems used by each Fund's mission critical service
providers. The Funds have also sought and received assurances from these service
providers that they are devoting significant resources to prevent material
adverse consequences to the Funds. Whether these steps will be effective can
only be known for certain in the year 2000. While such assurances have been
received, year 2000 problems may ultimately negatively affect the companies and
governments whose securities the Funds purchase, which may have an impact on the
value of the Funds' shares. There is additional information on these risks in
the Statement of Additional Information.

<PAGE>
4 PROSPECTUS

TREASURY SECURITIES FUND

FUND SUMMARY

<TABLE>
<S> <C>
INVESTMENT GOAL Preserving principal and maintaining liquidity while
providing current income
- -----------------------------------------------------------------------------------------------
SHARE PRICE VOLATILITY Very low
- -----------------------------------------------------------------------------------------------
PRINCIPAL INVESTMENT STRATEGY The Fund is professionally managed to provide liquidity,
diversification and a competitive yield by investing in U.S.
Treasury securities
</TABLE>

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

INVESTMENT STRATEGY

The Fund invests exclusively in U.S. Treasury obligations and repurchase
agreements fully-collateralized by U.S. Treasury obligations.

Using a top-down strategy and bottom-up security selection, the Adviser seeks
securities with an acceptable maturity that are marketable and liquid and offer
competitive yields. The Adviser also considers factors such as the anticipated
level of interest rates and the maturity of individual securities relative to
the maturity of the Fund as a whole. The Fund follows strict Investment Company
Act rules about the credit quality, maturity and diversification of its
investments.

WHAT ARE THE RISKS OF INVESTING IN THE FUND?

An investment in the Fund is subject to income risk, which is the possibility
that the Fund's yield will decline due to falling interest rates.

Although the Fund's U.S. Treasury securities are considered to be among the
safest investments, they are not guaranteed against price movements due to
changing interest rates.

AN INVESTMENT IN THE FUND IS NOT A BANK DEPOSIT. ALTHOUGH THE FUND SEEKS TO
MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00, YOU MAY LOSE MONEY BY INVESTING IN
THE FUND.
<PAGE>
PROSPECTUS 5

TREASURY SECURITIES FUND

PERFORMANCE INFORMATION

The bar chart and the performance table below illustrate the risks and
volatility of an investment in the Fund. Of course, the Fund's past performance
does not necessarily indicate how the Fund will perform in the future.

This bar chart shows changes in the performance of the Fund's Class A Shares
from year to year for 10 years.*

EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC

<TABLE>
<S> <C>
BEST QUARTER WORST QUARTER
2.28% 0.69%
(6/30/89) (6/30/93)
</TABLE>

* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO SEPTEMBER 30, 1999, WAS
3.38%.

THIS TABLE SHOWS THE FUND'S AVERAGE ANNUAL TOTAL RETURNS FOR CLASS A SHARES FOR
THE PERIODS ENDED DECEMBER 31, 1998.

<TABLE>
<CAPTION>
SINCE
1 YEAR 5 YEARS 10 YEARS INCEPTION
<S> <C> <C> <C> <C>
- -----------------------------------------------------------------
TREASURY SECURITIES
FUND -- CLASS A
SHARES 5.12% 4.98% 5.39% 6.42%*
- -----------------------------------------------------------------
</TABLE>

* THE INCEPTION DATE FOR CLASS A SHARES OF THE FUND IS JANUARY 18, 1982.

Please call 1-800-DIAL-SEI to obtain the Fund's current yield.

- --------------------------------------------------------------------------------
- ------------------------------------------------------------------------
FUND FEES AND EXPENSES

THIS TABLE DESCRIBES THE HIGHEST FEES AND EXPENSES THAT YOU MAY CURRENTLY PAY IF
YOU BUY AND HOLD SHARES OF THE FUND.

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
(EXPENSES DEDUCTED FROM FUND ASSETS) CLASS A SHARES
<S> <C>
Investment Advisory Fees 0.03%
Distribution (12b-1) Fees None
Other Expenses 0.70%
-----
TOTAL ANNUAL FUND OPERATING EXPENSES 0.73%
Fee Waivers and Expense Reimbursements 0.29%
-----
NET EXPENSES 0.44%*
</TABLE>

* SEI INVESTMENTS FUND MANAGEMENT HAS CONTRACTUALLY AGREED TO WAIVE FEES AND TO
REIMBURSE EXPENSES IN ORDER TO KEEP TOTAL OPERATING EXPENSES FROM EXCEEDING
0.44%.

For more information about these fees, see "Investment Adviser."

EXAMPLE

This Example is intended to help you compare the cost of investing in the Fund
with the cost of investing in other mutual funds. The Example assumes that you
invest $10,000 in the Fund for the time periods indicated and that you sell your
shares at the end of the period. The Example also assumes that each year your
investment has a 5% return, that Fund expenses remain the same, and that you
reinvest all dividends and distributions. Although your actual costs and returns
might be different, your approximate costs of investing $10,000 in the Fund
would be:

<TABLE>
<CAPTION>
1 YEAR 3 YEARS 5 YEARS 10 YEARS
<S> <C> <C> <C> <C>
Treasury Securities Fund -- Class A Shares $45 $141 $246 $555
</TABLE>

<PAGE>
6 PROSPECTUS

GOVERNMENT SECURITIES FUND

FUND SUMMARY

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

INVESTMENT STRATEGY

The Fund invests exclusively in U.S. Treasury obligations, obligations issued or
guaranteed as to principal and interest by agencies or instrumentalities of the
U.S. government, and repurchase agreements fully-collateralized by such
obligations.

Using a top-down strategy and bottom-up security selection, the Adviser seeks
securities with an acceptable maturity that are marketable and liquid and offer
competitive yields. The Adviser also considers factors such as the anticipated
level of interest rates and the maturity of individual securities relative to
the maturity of the Fund as a whole. The Fund follows guidelines about the
credit quality, maturity and diversification of its investments. With respect to
maturity, these guidelines are more restrictive than the Investment Company Act
rules applicable to money market funds.

WHAT ARE THE RISKS OF INVESTING IN THE FUND?

An investment in the Fund is subject to income risk, which is the possibility
that the Fund's yield will decline due to falling interest rates.

Although the Fund's U.S. government securities are considered to be among the
safest investments, they are not guaranteed against price movements due to
changing interest rates. Obligations issued by some U.S. government agencies are
backed by the U.S. Treasury, while others are backed solely by the ability of
the agency to borrow from the U.S. Treasury or by the agency's own resources.

AN INVESTMENT IN THE FUND IS NOT A BANK DEPOSIT. ALTHOUGH THE FUND SEEKS TO
MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00, YOU MAY LOSE MONEY BY INVESTING IN
THE FUND.
<PAGE>
PROSPECTUS 7

GOVERNMENT SECURITIES FUND

PERFORMANCE INFORMATION

This bar chart shows changes in the performance of the Fund's Class A Shares
from year to year for 10 years.*

EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC

<TABLE>
<S> <C>
BEST QUARTER WORST QUARTER
2.33% 0.69%
(6/30/89) (6/30/93)
</TABLE>

* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO SEPTEMBER 30, 1999, WAS
3.46%.

THIS TABLE SHOWS THE FUND'S AVERAGE ANNUAL TOTAL RETURNS FOR CLASS A SHARES FOR
THE PERIODS ENDED DECEMBER 31, 1998.

<TABLE>
<CAPTION>
SINCE
1 YEAR 5 YEARS 10 YEARS INCEPTION
<S> <C> <C> <C> <C>
- -----------------------------------------------------------------
GOVERNMENT SECURITIES
FUND -- CLASS A
SHARES 5.06% 4.97% 5.41% 6.49%*
- -----------------------------------------------------------------
</TABLE>

* THE INCEPTION DATE FOR CLASS A SHARES OF THE FUND IS JANUARY 18, 1982.

Please call 1-800-DIAL-SEI to obtain the Fund's current yield.

- --------------------------------------------------------------------------------
- ------------------------------------------------------------------------
FUND FEES AND EXPENSES

THIS TABLE DESCRIBES THE HIGHEST FEES AND EXPENSES THAT YOU MAY CURRENTLY PAY IF
YOU BUY AND HOLD SHARES OF THE FUND.

* SEI INVESTMENTS FUND MANAGEMENT HAS CONTRACTUALLY AGREED TO WAIVE FEES AND TO
REIMBURSE EXPENSES IN ORDER TO KEEP TOTAL OPERATING EXPENSES FROM EXCEEDING
0.44%.

For more information about these fees, see "Investment Adviser."

EXAMPLE

<TABLE>
<CAPTION>
1 YEAR 3 YEARS 5 YEARS 10 YEARS
<S> <C> <C> <C> <C>
Government Fund -- Class A Shares $45 $141 $246 $555
</TABLE>

<PAGE>
8 PROSPECTUS

PRIME OBLIGATION FUND

FUND SUMMARY

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

INVESTMENT STRATEGY

The Prime Obligation Fund is comprised of short-term debt obligations of U.S.
issuers that are rated in one of the two highest rating categories by nationally
recognized statistical rating organizations or that the Adviser determines are
of comparable quality. The Fund invests in: (i) commercial paper (including
asset-backed commercial paper) rated in the highest short-term rating category
by at least one nationally recognized statistical rating organization; (ii)
certificates of deposit, time deposits, bankers' acceptances, bank notes and
other obligations of U.S. commercial banks or savings and loan institutions that
meet certain asset requirements; (iii) short-term corporate obligations
(including asset-backed securities) rated in one of the two highest long-term
rating categories; (iv) short-term obligations issued by state and local
governments; and (v) U.S. Treasury obligations and obligations issued or
guaranteed as to principal and interest by agencies or instrumentalities of the
U.S. government. The Fund may also enter into fully-collateralized repurchase
agreements.

Using a top-down strategy and bottom-up security selection, the Adviser seeks
securities with an acceptable maturity, that are marketable and liquid, offer
competitive yields, and are issued by issuers that are on a sound financial
footing. The Adviser also considers factors such as the anticipated level of
interest rates and the maturity of individual securities relative to the
maturity of the Fund as a whole. The Fund follows guidelines about the credit
quality, maturity and diversification of its investments. With respect to credit
quality and maturity, these guidelines are more restrictive than the Investment
Company Act rules applicable to money market funds.

WHAT ARE THE RISKS OF INVESTING IN THE FUND?

An investment in the Fund is subject to income risk, which is the possibility
that the Fund's yield will decline due to falling interest rates.

AN INVESTMENT IN THE FUND IS NOT A BANK DEPOSIT. ALTHOUGH THE FUND SEEKS TO
MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00, YOU MAY LOSE MONEY BY INVESTING IN
THE FUND.
<PAGE>
PROSPECTUS 9

PRIME OBLIGATION FUND

PERFORMANCE INFORMATION

This bar chart shows changes in the performance of the Fund's Class A Shares
from year to year for 10 years.*

EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC

<TABLE>
<S> <C>
BEST QUARTER WORST QUARTER
2.38% 0.69%
(6/30/89) (6/30/93)
</TABLE>

* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO SEPTEMBER 30, 1999, WAS
3.57%.

THIS TABLE SHOWS THE FUND'S AVERAGE ANNUAL TOTAL RETURNS FOR CLASS A SHARES FOR
THE PERIODS ENDED DECEMBER 31, 1998.

<TABLE>
<CAPTION>
SINCE
1 YEAR 5 YEARS 10 YEARS INCEPTION
<S> <C> <C> <C> <C>
- ----------------------------------------------------------------------
PRIME OBLIGATION
FUND -- CLASS A
SHARES 5.30% 5.11% 5.53% 6.11%*
- ----------------------------------------------------------------------
</TABLE>

* THE INCEPTION DATE FOR CLASS A SHARES OF THE FUND IS JANUARY 18, 1982.

Please call 1-800-DIAL-SEI to obtain the Fund's current yield.

- --------------------------------------------------------------------------------
- ------------------------------------------------------------------------
FUND FEES AND EXPENSES

THIS TABLE DESCRIBES THE HIGHEST FEES AND EXPENSES THAT YOU MAY CURRENTLY PAY IF
YOU BUY AND HOLD SHARES OF THE FUND.

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
(EXPENSES DEDUCTED FROM FUND ASSETS) CLASS A SHARES
<S> <C>
Investment Advisory Fees 0.03%
Distribution (12b-1) Fees None
Other Expenses 0.70%
------
TOTAL ANNUAL FUND OPERATING EXPENSES 0.73%
Fee Waivers and Expense Reimbursements 0.29%
------
NET EXPENSES 0.44%*
</TABLE>

* SEI INVESTMENTS FUND MANAGEMENT HAS CONTRACTUALLY AGREED TO WAIVE FEES AND TO
REIMBURSE EXPENSES IN ORDER TO KEEP TOTAL OPERATING EXPENSES FROM EXCEEDING
0.44%.

For more information about these fees, see "Investment Adviser."

EXAMPLE

<TABLE>
<CAPTION>
1 YEAR 3 YEARS 5 YEARS 10 YEARS
<S> <C> <C> <C> <C>
Prime Obligation Fund -- Class A Shares $45 $141 $246 $555
</TABLE>

<PAGE>
10 PROSPECTUS

THE FUNDS' OTHER INVESTMENTS

This prospectus describes the Funds' primary investment strategies. Each Fund is
required to invest at least 80% of its assets, but normally will invest 100% of
its assets, in the types of securities described in this prospectus. However,
the Funds also may invest in other securities, use other strategies and engage
in other investment practices, which are described in detail in the Funds'
Statement of Additional Information (SAI).

The investments and strategies described in this prospectus are those that the
Funds use under normal conditions. During unusual economic or market conditions,
or for temporary defensive or liquidity purposes, the Funds may invest up to
100% of their assets in cash or cash equivalents that would not ordinarily be
consistent with the Funds' objectives. Of course, there is no guarantee that the
Funds will achieve their investment goal.

INVESTMENT ADVISER

The Investment Adviser makes investment decisions for the Funds and continuously
reviews, supervises and administers the Funds' investment program. The Board of
Trustees supervises the Adviser and establishes policies that the Adviser must
follow in its management activities.

Wellington Management Company, LLP ("Wellington"), serves as the Adviser to the
Funds. As of September 30, 1999, Wellington had approximately $217 billion in
assets under management. For the fiscal year ended June 30, 1999, each Fund paid
Wellington advisory fees of 0.02% of average daily net assets.

John C. Keogh is the portfolio manager of the Funds. Mr. Keogh has been an
investment professional with Wellington since 1983.

PURCHASING AND SELLING FUND SHARES

This section tells you how to purchase or sell (sometimes called "redeem")
shares of the Funds. The Funds offer Class A Shares only to financial
institutions or intermediaries for their own or their customers' accounts. For
information on how to open an account and set up procedures for placing
transactions, please call 1-800-DIAL-SEI.

HOW TO PURCHASE FUND SHARES

Financial institutions and intermediaries may purchase Class A Shares by placing
orders with the Funds' Transfer Agent (or its authorized agent). Institutions
and intermediaries that use certain SEI proprietary systems may place orders
electronically through those systems. Cash investments must be transmitted or
delivered in federal funds to the Funds' wire agent by the close of business on
the same day the order is placed. The Funds may reject any purchase order if
they determine that accepting the order would not be in the best interests of
the Funds or their shareholders.

When you purchase or sell Fund shares through certain financial institutions
(rather than directly from the Fund), you may have to transmit your purchase and
sale requests to certain financial institutions at an earlier time for your
transaction to become effective that day. This allows these financial
institutions time to process your requests and transmit them to the Funds.
<PAGE>
PROSPECTUS 11

PURCHASING AND SELLING FUND SHARES

Certain other intermediaries, including certain broker-dealers and shareholder
organizations, are authorized to accept purchase, redemption and exchange
requests for Fund shares. These requests are normally executed at the net asset
value per share (NAV) next determined after the intermediary receives the
request. These authorized intermediaries are responsible for transmitting
requests and delivering funds on a timely basis.

Investors who deal directly with a financial institution or financial
intermediary will have to follow the institution's or intermediary's procedures
for transacting with the Funds. For more information about how to purchase or
sell Fund shares through your financial institution, you should contact your
financial institution directly. Investors may be charged a fee for purchase
and/or redemption transactions effectuated through certain of these
broker-dealers or other financial intermediaries.

Each Fund's NAV is calculated once each Business Day at 2:00 p.m., Eastern time
(3:00 p.m., Eastern time for the Prime Obligation Fund). So, for you to be
eligible to receive dividends declared on the day you submit your purchase
order, generally the Funds (or their authorized intermediaries) must receive
your purchase order and federal funds (readily available funds) before the Funds
calculate their NAV.

HOW THE FUNDS CALCULATE NAV

NAV for one Fund share is the value of that share's portion of all of the net
assets in the Fund.

The Funds value their securities by utilizing the amortized cost valuation
method (as described in the SAI). If the Funds think amortized cost is
unreliable, fair value prices may be determined in good faith using methods
approved by the Board of Trustees. The Funds expect their NAV to remain constant
at $1.00 per share, although there is no guarantee that any Fund can accomplish
this.

HOW TO SELL YOUR FUND SHARES

Holders of Class A Shares may sell shares on any Business Day by following the
procedures established when they opened their account or accounts with their
financial institution or intermediary. You may also sell your shares by
contacting your financial institution or financial intermediary by telephone.
Your financial institution or intermediary may charge you a fee for its
services. The sale price of each share will be the next NAV determined after the
Funds (or their authorized intermediaries) receive your request.

RECEIVING YOUR MONEY

Normally, the Funds will make payment on your sale as promptly as possible after
they receive your request, but it may take up to three Business Days. Your
proceeds will be wired to your bank account.

REDEMPTIONS IN KIND

The Funds generally pay sale (redemption) proceeds in cash. However, under
unusual conditions that make the payment of cash unwise (and for the protection
of the Funds' remaining shareholders) the Funds might pay all or part of your
redemption proceeds in liquid securities with a market value equal to the
redemption price (redemption in kind). It is highly unlikely that your shares
would ever be redeemed in kind, but if they were, you might have to pay
transaction costs to sell the securities distributed to you, as well as taxes on
any capital gains from the sale as with any redemption.

SUSPENSION OF YOUR RIGHT TO SELL YOUR SHARES

The Funds may suspend your right to sell your shares if the NYSE restricts
trading, the SEC declares an emergency or for other reasons. More information
about this is in the SAI.
<PAGE>
12 PROSPECTUS

DIVIDENDS, DISTRIBUTIONS AND TAXES

DISTRIBUTION OF FUND SHARES

SEI Investments Distribution Co. (SIDCo.) is the distributor of the shares of
the Funds. SIDCo. receives no compensation for distributing the Funds' Class A
Shares.

For Class A Shares, shareholder servicing fees, as a percentage of average daily
net assets, may be up to 0.25%. The Distributor has voluntarily agreed to waive
the shareholder servicing fees applicable to Class A Shares of the Funds. The
Distributor has no current intention to discontinue this voluntary waiver.

DIVIDENDS AND DISTRIBUTIONS

Each Fund declares dividends daily and distributes its income monthly. The Funds
make distributions of capital gains, if any, at least annually.

You will receive dividends and distributions in cash unless otherwise stated.

TAXES

PLEASE CONSULT YOUR TAX ADVISOR REGARDING YOUR SPECIFIC QUESTIONS ABOUT FEDERAL,
STATE AND LOCAL INCOME TAXES. Below the Funds have summarized some important tax
issues that affect the Funds and their shareholders. This summary is based on
current tax laws, which may change.

The Funds will distribute substantially all of its income and capital gains, if
any. The dividends and distributions you receive may be subject to federal,
state and local taxation, depending upon your tax situation. If so, they are
taxable whether or not you reinvest them. Income distributions are generally
taxable at ordinary tax rates. Capital gains distributions are generally taxable
at the rates applicable to long-term capital gains. EACH SALE OF FUND SHARES IS
A TAXABLE EVENT.

MORE INFORMATION ABOUT TAXES IS IN THE FUNDS' SAI.
<PAGE>
PROSPECTUS 13

FINANCIAL HIGHLIGHTS

The tables that follow present performance information about Class A Shares of
the Funds. This information is intended to help you understand the Funds'
financial performance for the past five years. Some of this information reflects
financial information for a single Fund share. The total returns in the table
represent the rate that you would have earned (or lost) on an investment in a
Fund, assuming you reinvested all of your dividends and distributions.

This information has been audited by PricewaterhouseCoopers LLP, independent
public accountants. Their report, along with the Funds' financial statements,
appears in the annual report that accompanies the Funds' SAI. You can obtain the
annual report, which contains more performance information, at no charge by
calling 1-800-DIAL-SEI.

SEI LIQUID ASSET TRUST -- FOR THE YEARS ENDED JUNE 30,

FOR A SHARE OUTSTANDING THROUGHOUT EACH PERIOD

REALIZED DISTRIBUTIONS NET
NET ASSET AND DISTRIBUTIONS FROM ASSET
VALUE NET UNREALIZED FROM NET REALIZED VALUE NET ASSETS
BEGINNING INVESTMENT GAINS ON INVESTMENT CAPITAL END TOTAL END OF
OF PERIOD INCOME SECURITIES INCOME GAINS OF PERIOD RETURN PERIOD (000)
--------- ---------- ---------- ------------- ------------- --------- ------ ------------
<S> <C> <C> <C> <C> <C> <C> <C> <C>
- -------------------
TREASURY SECURITIES
CLASS A
- -----------------
1999.............. $1.00 $0.05 -- $(0.05) -- $1.00 4.72% $ 565,897
1998.............. 1.00 0.05 -- (0.05) -- 1.00 5.29 603,783
1997.............. 1.00 0.05 -- (0.05) -- 1.00 5.10 706,232
1996.............. 1.00 0.05 -- (0.05) -- 1.00 5.37 832,393
1995.............. 1.00 0.05 -- (0.05) -- 1.00 5.05 1,254,888
- -----------------------
GOVERNMENT SECURITIES
CLASS A
- --------------------
1999.............. $1.00 $0.05 -- $(0.05) -- $1.00 4.74% $ 108,468
1998.............. 1.00 0.05 -- (0.05) -- 1.00 5.21 105,201
1997.............. 1.00 0.05 -- (0.05) -- 1.00 5.09 148,606
1996.............. 1.00 0.05 -- (0.05) -- 1.00 5.30 169,133
1995.............. 1.00 0.05 -- (0.05) -- 1.00 5.18 200,768
- -----------------
PRIME OBLIGATION
CLASS A
- ---------------
1999.............. $1.00 $0.05 -- $(0.05) -- $1.00 4.97% $1,335,301
1998.............. 1.00 0.05 -- (0.05) -- 1.00 5.40 947,154
1997.............. 1.00 0.05 -- (0.05) -- 1.00 5.20 823,270
1996.............. 1.00 0.05 -- (0.05) -- 1.00 5.39 747,852
1995.............. 1.00 0.05 -- (0.05) -- 1.00 5.20 940,863

<CAPTION>
RATIO OF
NET
RATIO OF RATIO OF INVESTMENT
NET EXPENSES INCOME
RATIO OF INVESTMENT TO AVERAGE TO AVERAGE
EXPENSES INCOME NET ASSETS NET ASSETS
TO AVERAGE TO AVERAGE (EXCLUDING (EXCLUDING
NET ASSETS NET ASSETS WAIVERS) WAIVERS)
---------- ---------- ---------- ----------
<S> <C> <C> <C> <C>
- -------------------
TREASURY SECURITIES
CLASS A
- -----------------
1999.............. 0.44% 4.62% 0.73% 4.33%
1998.............. 0.44 5.17 0.73 4.88
1997.............. 0.44 4.98 0.74 4.68
1996.............. 0.44 5.27 0.52 5.19
1995.............. 0.44 4.93 0.54 4.83
- ----------------------
GOVERNMENT SECURITIES
CLASS A
- --------------------
1999.............. 0.44% 4.66% 0.73% 4.37%
1998.............. 0.44 5.10 0.73 4.81
1997.............. 0.44 4.98 0.71 4.71
1996.............. 0.44 5.19 0.54 5.09
1995.............. 0.44 5.04 0.53 4.95
- -----------------
PRIME OBLIGATION
CLASS A
- ---------------
1999.............. 0.44% 4.84% 0.73% 4.55%
1998.............. 0.44 5.27 0.73 4.98
1997.............. 0.44 5.08 0.74 4.78
1996.............. 0.44 5.27 0.53 5.18
1995.............. 0.44 5.21 0.53 5.12
</TABLE>

Amounts designated as "--" are either $0 or have been rounded to $0.

<PAGE>
SEI Liquid
Asset Trust

INVESTMENT ADVISER

WELLINGTON MANAGEMENT COMPANY, LLP
75 STATE STREET
BOSTON, MA 02109

DISTRIBUTOR

SEI INVESTMENTS DISTRIBUTION CO.
ONE FREEDOM VALLEY DRIVE
OAKS, PA 19456

LEGAL COUNSEL

MORGAN, LEWIS & BOCKIUS LLP

More information about the Funds is available without charge through the
following:

STATEMENT OF ADDITIONAL INFORMATION (SAI)
- ------------------------------------------------

The SAI dated October 31, 1999, includes more detailed information about SEI
Liquid Asset Trust. The SAI is on file with the SEC and is incorporated by
reference into this prospectus. This means that the SAI, for legal purposes, is
a part of this prospectus.

ANNUAL AND SEMI-ANNUAL REPORTS
- ------------------------------------------------

These reports list the Funds' holdings and contain information from the Funds'
managers about strategies and recent market conditions and trends and their
impact on performance. The reports also contain detailed financial information
about the Fund.

TO OBTAIN MORE INFORMATION:
- ------------------------------------------------

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

BY TELEPHONE: Call 1-800-DIAL-SEI

BY MAIL: Write to the Funds at:
One Freedom Valley Drive
Oaks, PA 19456

BY INTERNET: http://www.seic.com

FROM THE SEC:: You can also obtain the SAI or the Annual and
Semi-Annual Reports, as well as other information about SEI Daily Income Trust,
from the SEC's website ("http://www.sec.gov"). You may review and copy documents
at the SEC Public Reference Room in Washington, DC (for information call
1-800-SEC-0330). You may request documents by mail from the SEC, upon payment of
a duplicating fee, by writing to: Securities and Exchange Commission, Public
Reference Section, Washington, DC 20549-6009.

The Funds' Investment Company Act registration number is 811-03231.

- --------------------------------------------------------------------------------
<PAGE>
SEI
LIQUID
ASSET
TRUST
CLASS D SHARES

PROSPECTUS
OCTOBER 31, 1999

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

TREASURY SECURITIES FUND
---------------------------------------------------------

ADVISER
WELLINGTON MANAGEMENT COMPANY, LLP

SEI Liquid Asset Trust is a mutual fund family that offers different classes of
shares in separate investment portfolios (Funds). This prospectus gives you
important information about the Class D Shares of the Treasury Securities Fund
that you should know before investing. Please read this prospectus and keep it
for future reference.

THIS PROSPECTUS HAS BEEN ARRANGED INTO DIFFERENT SECTIONS SO THAT YOU CAN EASILY
REVIEW THIS IMPORTANT INFORMATION. ON THE NEXT PAGE, THERE IS SOME GENERAL
INFORMATION YOU SHOULD KNOW ABOUT RISK AND RETURN. FOR MORE DETAILED INFORMATION
ABOUT THE FUND, PLEASE SEE:

PRINCIPAL INVESTMENT STRATEGIES AND RISKS............................4

PERFORMANCE INFORMATION AND EXPENSES.................................5

THE FUND'S OTHER INVESTMENTS.........................................6

THE INVESTMENT ADVISER...............................................6

PURCHASING, SELLING AND EXCHANGING FUND SHARES.......................6

DIVIDENDS AND DISTRIBUTIONS..........................................8

TAXES................................................................9

FINANCIAL HIGHLIGHTS................................................10

HOW TO OBTAIN MORE INFORMATION ABOUT
SEI LIQUID ASSET TRUST......................................Back Cover
<PAGE>
PROSPECTUS 3

RISK/RETURN INFORMATION

The Fund is a mutual fund. A mutual fund pools shareholders' money and, using
professional investment managers, invests it in securities.

The Fund has its own investment goal and strategies for reaching that goal. The
Fund's assets are managed under the direction of its Adviser. The Adviser
invests the Fund's assets in a way it believes will help the Fund achieve its
goal. Still, investing in the Fund involves risk, and there is no guarantee that
the Fund will achieve its goal. In fact, no matter how good a job the Adviser
does, you could lose money on your investment in the Fund, just as you could
with other investments. A Fund share is not a bank deposit and it is not insured
or guaranteed by the FDIC or any other government agency.

ALTHOUGH THE FUND IS MANAGED TO MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00, IT
IS POSSIBLE TO LOSE MONEY BY INVESTING IN THE FUND.

- --------------------------------------------------------------------------------
YEAR 2000 RISKS

Like other mutual funds (and most organizations around the world), the Fund
could be affected by computer problems related to the transition to the year
2000. While no one knows if these problems will have any impact on the Fund or
on the financial markets in general, the Fund is taking steps to protect Fund
investors. These include efforts to ensure that the Fund's own systems are
prepared to make the transition to the year 2000, and to determine that the
problem will not affect the systems used by the Fund's mission critical service
providers. The Fund has also sought and received assurances from these service
providers that they are devoting significant resources to prevent material
adverse consequences to the Fund. Whether these steps will be effective can only
be known for certain in the year 2000. While such assurances have been received,
year 2000 problems may ultimately negatively affect the companies and
governments whose securities the Fund purchases, which may have an impact on the
value of the Fund's shares. There is additional information on these risks in
the Statement of Additional Information.
<PAGE>
4 PROSPECTUS

TREASURY SECURITIES FUND

FUND SUMMARY

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

INVESTMENT STRATEGY

The Fund invests exclusively in U.S. Treasury obligations and repurchase
agreements fully-collateralized by U.S. Treasury obligations.

WHAT ARE THE RISKS OF INVESTING IN THE FUND?

An investment in the Fund is subject to income risk, which is the possibility
that the Fund's yield will decline due to falling interest rates.

Although the Fund's U.S. Treasury securities are considered to be among the
safest investments, they are not guaranteed against price movements due to
changing interest rates.

AN INVESTMENT IN THE FUND IS NOT A BANK DEPOSIT. ALTHOUGH THE FUND SEEKS TO
MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00, YOU MAY LOSE MONEY BY INVESTING IN
THE FUND.
<PAGE>
PROSPECTUS 5

TREASURY SECURITIES FUND

PERFORMANCE INFORMATION

This bar chart shows changes in the performance of the Fund's Class D Shares
from year to year for four years.*

EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC

<TABLE>
<CAPTION>
BEST QUARTER WORST QUARTER
<S> <C>
1.33% 1.07%
(6/30/95) (12/31/98)
</TABLE>

* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO SEPTEMBER 30, 1999, WAS
3.11%.

This table shows the Fund's average annual total returns for Class D Shares for
the periods ended December 31, 1998.

<TABLE>
<CAPTION>
1 YEAR SINCE INCEPTION
<S> <C> <C>
- --------------------------------------------------------
TREASURY SECURITIES FUND
-- CLASS D SHARES 4.75% 4.75%*
- --------------------------------------------------------
</TABLE>

* THE INCEPTION DATE FOR CLASS D SHARES OF THE FUND IS MAY 4, 1994.

Please call 1-800-DIAL-SEI to obtain the Fund's current yield.

- --------------------------------------------------------------------------------
- ------------------------------------------------------------------------
FUND FEES AND EXPENSES
THIS TABLE DESCRIBES THE HIGHEST FEES AND EXPENSES THAT YOU MAY CURRENTLY PAY IF
YOU BUY AND HOLD SHARES OF THE FUND.

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
(EXPENSES DEDUCTED FROM FUND ASSETS) CLASS D SHARES
<S> <C>
Investment Advisory Fees 0.03%
Distribution (12b-1) Fees 0.25%
Other Expenses 0.60%
-----
TOTAL ANNUAL FUND OPERATING EXPENSES 0.88%
Fee Waivers and Expense Reimbursements 0.04%
-----
NET EXPENSES 0.84%*
</TABLE>

* SEI INVESTMENTS FUND MANAGEMENT HAS CONTRACTUALLY AGREED TO WAIVE FEES AND TO
REIMBURSE EXPENSES IN ORDER TO KEEP TOTAL OPERATING EXPENSES FROM EXCEEDING
0.84%.

The Fund's total actual annual fund operating expenses for the most recent
fiscal year were less than the amount shown above because the Adviser,
Administrator and/or Distributor are each voluntarily waiving a portion of their
fees in order to keep total operating expenses at a specified level. The
Adviser, Administrator and or Distributor may each discontinue all or part of
their waiver at any time. With this fee waiver, the Fund's actual total
operating expenses are as follows:

<TABLE>
<S> <C>
TREASURY SECURITIES FUND -- CLASS D SHARES 0.79%
</TABLE>

For more information about these fees, see "Investment Adviser" and
"Distribution of Fund Shares."

EXAMPLE

This Example is intended to help you compare the cost of investing in the Fund
with the cost of investing in other mutual funds. The Example assumes that you
invest $10,000 in the Fund for the time periods indicated and that you sell your
shares at the end of the period. The Example also assumes that each year your
investment has a 5% return, that Fund expenses remain the same, and that you
reinvest dividends and distributions. Although your actual costs and returns
might be different, your approximate costs of investing $10,000 in the Fund
would be:

<TABLE>
<CAPTION>
1 YEAR 3 YEARS 5 YEARS 10 YEARS
<S> <C> <C> <C> <C>
Treasury Securities Fund -- Class D Shares $86 $268 $466 $1,037
</TABLE>

<PAGE>
6 PROSPECTUS

THE FUND'S OTHER INVESTMENTS

This prospectus describes the Fund's primary investment strategies. The Fund is
required to invest at least 80% of its assets, but normally will invest 100% of
its assets, in the types of securities described in this prospectus. However,
the Fund also may invest in other securities, use other strategies and engage in
other investment practices, which are described in detail in the Fund's
Statement of Additional Information (SAI).

The investments and strategies described in this prospectus are those that the
Fund uses under normal conditions. During unusual economic or market conditions,
or for temporary defensive or liquidity purposes, the Fund may invest up to 100%
of its assets in cash or cash equivalents that would not ordinarily be
consistent with the Fund's objectives. Of course, there is no guarantee that the
Fund will achieve its investment goal.

INVESTMENT ADVISER

The Investment Adviser makes investment decisions for the Fund and continuously
reviews, supervises and administers the Fund's investment program. The Board of
Trustees supervises the Adviser and establishes policies that the Adviser must
follow in its management activities.

Wellington Management Company, LLP ("Wellington"), serves as the Adviser to the
Fund. As of September 30, 1999, Wellington had approximately $217 billion in
assets under management. For the fiscal year ended June 30, 1999, the Fund paid
Wellington advisory fees of 0.02% of its average daily net assets.

John C. Keogh is the portfolio manager of the Fund. Mr. Keogh has been an
investment professional with Wellington since 1983.

PURCHASING, SELLING AND EXCHANGING FUND SHARES

This section tells you how to purchase or sell (sometimes called "redeem") Class
D Shares of the Fund. The Fund offers Class D Shares to individuals and
financial institutions for their own or their customers' accounts. For
information on how to open an account and set up procedures for placing
transactions, please call 1-800-DIAL-SEI.

HOW TO PURCHASE FUND SHARES

You may purchase shares on any day that the New York Stock Exchange is open for
business (a Business Day). However, Fund shares cannot be purchased by Federal
Reserve wire on Federal holidays on which wire transfers are restricted. The
Fund may reject any purchase order if it determines that accepting the order
would not be in the best interests of the Fund or its shareholders.

When you purchase or sell Fund shares through certain financial institutions
(rather than directly from the Fund), you may have to transmit your purchase and
sale requests to these financial institutions at an earlier time for your
transaction to become effective that day. This allows these financial
institutions time to process your requests and transmit them to the Fund.

Investors who deal directly with a financial institution or financial
intermediary will have to follow the institution's or intermediary's procedures
for transacting with the Fund. For more information about how to purchase or
sell Fund shares through your financial institution, you should contact your
financial institution directly. Investors may be charged a fee for purchase
and/or redemption transactions effectuated through certain of these
broker-dealers or other financial intermediaries.
<PAGE>
PROSPECTUS 7

PURCHASING, SELLING AND EXCHANGING FUND SHARES

The Fund's NAV is calculated once each Business Day at 2:00 p.m., Eastern time.
So, for you to be eligible to receive dividends declared on the day you submit
your purchase order, generally the Fund (or its authorized intermediary) must
receive your purchase order and federal funds (readily available funds) before
the Fund calculates its NAV.

HOW THE FUND CALCULATES NAV

NAV for one Fund share is the value of that share's portion of all of the net
assets in the Fund.

The Fund values its securities by utilizing the amortized cost valuation method
(as described in the SAI). If the Fund thinks amortized cost is unreliable, fair
value prices may be determined in good faith using methods approved by the Board
of Trustees. The Fund expects its NAV to remain constant at $1.00 per share,
although there is no guarantee that the Fund can accomplish this.

AUTOMATIC INVESTMENT PLAN

If you have a checking or savings account with a bank, you may purchase Class D
shares automatically through regular deductions from your account in amounts of
at least $25.

HOW TO SELL YOUR FUND SHARES

Holders of Class D Shares may sell shares on any Business Day by following the
procedures established when they opened their account or accounts with their
financial institution or intermediary. You may sell your shares by contacting
your financial institution or financial intermediary by mail or telephone. Your
financial institution or intermediary may charge you a fee for its services. The
Fund offers free check writing services to Class D shareholders. You may redeem
shares by writing checks on your account for $500 or more after establishing a
check-writing account through your financial institution/intermediary. The sale
price of each share will be the next NAV determined after the Fund (or its
authorized institution) receives your request.

SYSTEMATIC WITHDRAWAL PLAN

If you have at least $10,000 in your account, you may use the systematic
withdrawal plan. Under the plan you may arrange monthly, quarterly, semi-annual
or annual automatic withdrawals of at least $50 from any Fund. The proceeds of
each withdrawal will be mailed to you by check or, if you have a checking or
savings account with a bank, electronically transferred to your account.

RECEIVING YOUR MONEY

Normally, the Fund will make payment on your sale as promptly as possible after
it receives your request, but it may take up to three Business Days. Your
proceeds will be wired to your bank account.

REDEMPTIONS IN KIND

PURCHASING, SELLING AND EXCHANGING FUND SHARES

your shares would ever be redeemed in kind, but if they were, you might have to
pay transaction costs to sell the securities distributed to you, as well as
taxes on any capital gains from the sale as with any redemption.

SUSPENSION OF YOUR RIGHT TO SELL YOUR SHARES

The Fund may suspend your right to sell your shares if the NYSE restricts
trading, the SEC declares an emergency or for other reasons. More information
about this is in the SAI.

TELEPHONE TRANSACTIONS

Purchasing, selling and exchanging Fund shares over the telephone is extremely
convenient, but not without risk. Although the Fund has certain safeguards and
procedures to confirm the identity of callers and the authenticity of
instructions, the Fund is not responsible for any losses or costs incurred by
following telephone instructions the Fund reasonably believes to be genuine. If
you or your financial institution transact with the Fund over the telephone, you
will generally bear the risk of any loss.

DISTRIBUTION OF FUND SHARES

SEI Investments Distribution Co. (SIDCo.) is the distributor of the Class D
Shares of the Fund.

The Fund has adopted a distribution plan that allows the Fund to pay SIDCo.
distribution fees for the sale and distribution of its Class D Shares. Because
these fees are paid out of the Fund's assets continuously, over time these fees
will increase the cost of your investment and may cost you more than paying
other types of sales charges. For Class D Shares, the distribution fee is 0.25%
of the average daily net assets of the Fund.

The Distributor may, from time to time in its sole discretion, institute one or
more promotional incentive programs for dealers, which will be paid for by the
Distributor from any sales chare it receives or from any other source available
to it. Under any such program, the Distributor may provide incentives, in the
form of cash or other compensation, including merchandise, airline vouchers,
trips and vacation packages, to dealers selling Class D Shares of the Fund.

HOW TO EXCHANGE YOUR SHARES

You may exchange your Class D Shares of the Fund for Class D Shares of any other
SEI Fund on any Business Day by contacting your financial institution or
intermediary by mail or telephone. Your financial institution or intermediary
may charge you a fee for its services. This exchange privilege may be changed or
canceled at any time upon 60 days' notice.

When you exchange shares, you are really selling your shares and buying other
Fund shares. So, your sale price and purchase price will be based on the NAV
next calculated after the Fund receives your exchange request. If you exchange
into a Fund that is subject to a sales charge, you may have to pay the sales
charge charged by that Fund.

DIVIDENDS AND DISTRIBUTIONS

The Fund declares dividends daily and distributes its income monthly. The Fund
makes distributions of capital gains, if any, at least annually.

You will receive dividends and distributions in cash unless otherwise stated.

TAXES

PLEASE CONSULT YOUR TAX ADVISOR REGARDING YOUR SPECIFIC QUESTIONS ABOUT FEDERAL,
STATE AND LOCAL INCOME TAXES. Below the Fund has summarized some important tax
issues that affect the Fund and its shareholders. This summary is based on
current tax laws, which may change.

The Fund will distribute substantially all of its income and capital gains, if
any. The dividends and distributions you receive may be subject to federal,
state and local taxation, depending upon your tax situation. If so, they are
taxable whether or not you reinvest them. Income distributions are generally
taxable at ordinary income tax rates. Capital gains distributions are generally
taxable at the rates applicable to long-term capital gains. EACH SALE OR
EXCHANGE OF FUND SHARES IS A TAXABLE EVENT.

MORE INFORMATION ABOUT TAXES IS IN THE FUND'S SAI.
<PAGE>
PROSPECTUS 9

FINANCIAL HIGHLIGHTS

The table that follows presents performance information about Class D Shares of
the Fund. This information is intended to help you understand the Fund's
financial performance for the past five years, or, if shorter, the period of the
Fund's operations. Some of this information reflects financial information for a
single Fund share. The total returns in the table represent the rate that you
would have earned (or lost) on an investment in the Fund, assuming you
reinvested all of your dividends and distributions.

This information has been audited by PricewaterhouseCoopers LLP, independent
public accountants. Their report, along with the Fund's financial statements,
appears in the annual report that accompanies the Fund's SAI. You can obtain the
annual report, which contains more performance information, at no charge by
calling 1-800-DIAL-SEI.

SEI LIQUID ASSET TRUST -- FOR THE YEARS ENDED JUNE 30,

FOR A SHARE OUTSTANDING THROUGHOUT EACH PERIOD

Amounts designated as "--" are either $0 or have been rounded to $0.

<PAGE>
SEI Liquid
Asset Trust

INVESTMENT ADVISER

WELLINGTON MANAGEMENT COMPANY, LLP
75 STATE STREET
BOSTON, MA 02109

DISTRIBUTOR

SEI INVESTMENTS DISTRIBUTION CO.
ONE FREEDOM VALLEY DRIVE
OAKS, PA 19456

LEGAL COUNSEL

MORGAN, LEWIS & BOCKIUS LLP

More information about the Fund is available without charge through the
following:

STATEMENT OF ADDITIONAL INFORMATION (SAI)
- ------------------------------------------------

ANNUAL AND SEMI-ANNUAL REPORTS
- ------------------------------------------------

These reports list the Fund's holdings and contain information from the Fund's
managers about strategies and recent market conditions and trends and their
impact on performance. The reports also contain detailed financial information
about the Fund.

TO OBTAIN MORE INFORMATION:
- ------------------------------------------------

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

BY TELEPHONE: Call 1-800-DIAL-SEI

BY MAIL: Write to the Fund at:
One Freedom Valley Drive
Oaks, PA 19456

BY INTERNET: http://www.seic.com

FROM THE SEC: You can also obtain the SAI or the Annual and Semi-Annual Reports,
as well as other information about SEI Daily Income Trust, from the SEC's
website ("http://www.sec.gov"). You may review and copy documents at the SEC
Public Reference Room in Washington, DC (for information call 1-800-SEC-0330).
You may request documents by mail from the SEC, upon payment of a duplicating
fee, by writing to: Securities and Exchange Commission, Public Reference
Section, Washington, DC 20549-6009.

The Fund's Investment Company Act registration number is 811-03231.

- --------------------------------------------------------------------------------
<PAGE>

SEI LIQUID ASSET TRUST

CLASS A SHARES

PROSPECTUS
OCTOBER 31, 1999

INSTITUTIONAL CASH FUND

ADVISER:
WELLINGTON MANAGEMENT COMPANY, LLP

THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR DISAPPROVED ANY FUND
SHARES OR DETERMINED WHETHER THIS PROSPECTUS IS ACCURATE OR COMPLETE.
IT IS A CRIME FOR ANYONE TO TELL YOU OTHERWISE.

Page 1 of 13
<PAGE>

ABOUT THIS PROSPECTUS

SEI Liquid Asset Trust is a mutual fund family that offers different classes of
shares in separate investment portfolios (Funds). This prospectus gives you
important information about the Class A Shares of the Institutional Cash Fund
that you should know before investing. Please read this prospectus and keep it
for future reference.

THIS PROSPECTUS HAS BEEN ARRANGED INTO DIFFERENT SECTIONS SO THAT YOU CAN EASILY
REVIEW THIS IMPORTANT INFORMATION. ON THE NEXT PAGE, THERE IS SOME GENERAL
INFORMATION YOU SHOULD KNOW ABOUT RISK AND RETURN. FOR MORE DETAILED INFORMATION
ABOUT THE FUND, PLEASE SEE:

<TABLE>
<CAPTION>
PAGE
<S> <C>
PRINCIPAL INVESTMENT STRATEGIES AND RISKS..........................................XXX
PERFORMANCE INFORMATION AND EXPENSES...............................................XXX
THE FUND'S OTHER INVESTMENTS.......................................................XXX
THE INVESTMENT ADVISER.............................................................XXX
PURCHASING AND SELLING FUND SHARES.................................................XXX
DIVIDENDS AND DISTRIBUTIONS........................................................XXX
TAXES..............................................................................XXX
FINANCIAL HIGHLIGHTS...............................................................XXX
HOW TO OBTAIN MORE INFORMATION ABOUT
SEI LIQUID ASSET TRUST...........................................................Back Cover
</TABLE>

Page 2 of 13
<PAGE>

RISK/RETURN INFORMATION

The Fund is a mutual fund. A mutual fund pools shareholders' money and, using
professional investment managers, invests it in securities.

The Fund has its own investment goal and strategies for reaching that goal. The
Fund's assets are managed under the direction of its Adviser. The Adviser
invests the Fund's assets in a way that it believes will help the Fund achieve
its goal. Still, investing in the Fund involves risk, and there is no guarantee
that the Fund will achieve its goal. In fact, no matter how good a job the
Adviser does, you could lose money on your investment in the Fund, just as you
could with other investments. A Fund share is not a bank deposit and it is not
insured or guaranteed by the FDIC or any other government agency.

ALTHOUGH THE FUND IS MANAGED TO MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00,
IT IS POSSIBLE TO LOSE MONEY BY INVESTING IN THE FUND.

YEAR 2000 RISKS

Page 3 of 13
<PAGE>

INSTITUTIONAL CASH FUND

<TABLE>
<CAPTION>
FUND SUMMARY

<S> <C>
INVESTMENT GOAL Preserving principal and maintaining liquidity
while providing current income

SHARE PRICE VOLATILITY Very low

PRINCIPAL INVESTMENT STRATEGY The Fund is professionally managed to provide
liquidity, diversification and a competitive yield
by investing in U.S. Treasury securities
</TABLE>

INVESTMENT STRATEGY

The Fund invests exclusively in U.S. Treasury obligations.

WHAT ARE THE RISKS OF INVESTING IN THE FUND?

An investment in the Fund is subject to income risk, which is the possibility
that the Fund's yield will decline due to falling interest rates.

Although the Fund's U.S. Treasury securities are considered to be among the
safest investments, they are not guaranteed against price movements due to
changing interest rates.

AN INVESTMENT IN THE FUND IS NOT A BANK DEPOSIT. ALTHOUGH THE FUND SEEKS TO
MAINTAIN A CONSTANT PRICE PER SHARE OF $1.00, YOU MAY LOSE MONEY BY INVESTING IN
THE FUND.

Page 4 of 13
<PAGE>

PERFORMANCE INFORMATION

This bar chart shows changes in the performance of the Fund's Class A Shares
from year to year for ten years.*

<TABLE>
<S> <C> <C>
1988 0.07%
1989 0.09%
1990 0.11%
1991 0.04%
1992 0.02%
1993 0.03%
1994 0.03%
1995 0.03%
1996 0.05%
1997 0.02%
<CAPTION>
BEST QUARTER WORST QUARTER
0.11% 0.02%
(12/31/90) (12/31/92)
</TABLE>

* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE FUND
WAS CLOSED ON JANUARY 2, 1998. ALTHOUGH THE FUND ORIGINALLY COMMENCED OPERATIONS
ON DECEMBER 31, 1986, IT WAS ONLY OPEN TO SHAREHOLDERS FOR A FEW DAYS EACH YEAR.
THE PERFORMANCE INFORMATION HAS NOT BEEN ANNUALIZED.

THIS TABLE SHOWS THE FUND'S AVERAGE ANNUAL TOTAL RETURNS FOR CLASS A SHARES FOR
THE PERIODS ENDED DECEMBER 31, 1997. AS OF SEPTEMBER 30, 1999, THE FUND WAS NO
LONGER OFFERING SHARES.

<TABLE>
<CAPTION>
SINCE
1 YEAR 5 YEARS 10 YEARS INCEPTION
<S> <C> <C> <C> <C>
INSTITUTIONAL CASH FUND - CLASS A SHARES 0.02% 0.03% 0.05% 0.05%*
</TABLE>

* The inception date for Class A Shares of the Fund is December 31, 1986.

Please call 1-800-DIAL-SEI to obtain the Fund's current yield.

Page 5 of 13
<PAGE>

FUND FEES AND EXPENSES

THIS TABLE DESCRIBES THE HIGHEST FEES AND EXPENSES THAT YOU MAY CURRENTLY PAY IF
YOU BUY AND HOLD SHARES OF THE FUND.

<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
(EXPENSES DEDUCTED FROM FUND ASSETS) CLASS A SHARES
- ------------------------------------------------------------------------------------------------------------------
<S> <C>
Investment Advisory Fees 0.03%
Distribution (12b-1) Fees None
Other Expenses 0.70%
-----
Total Annual Fund Operating Expenses 0.73%*
- ------------------------------------------------------------------------------------------------------------------
</TABLE>

* The Fund's total actual annual fund operating expenses for the most recent
fiscal year were less than the amount shown above because the Adviser,
Administrator, and/or Distributor are each voluntarily waiving a portion of
their fees in order to keep total operating expenses at a specified level. The
Adviser, Administrator, and or Distributor may each discontinue all or part of
their waiver at any time. With this fee waiver, the Fund's actual total
operating expenses are as follows:

Institutional Cash Fund -- Class A Shares 0.44%

For more information about these fees, see "Investment Adviser."

EXAMPLE

<TABLE>
<CAPTION>
1 YEAR 3 YEARS 5 YEARS 10 YEARS
<S> <C> <C> <C> <C>
INSTITUTIONAL CASH FUND - CLASS A SHARES $75 $233 $406 $906
</TABLE>

Page 6 of 13
<PAGE>

THE FUND'S OTHER INVESTMENTS

The investments and strategies described in this prospectus are those that the
Fund uses under normal conditions. During unusual economic or market conditions,
or for temporary defensive or liquidity purposes, the Fund may invest up to 100%
of its assets in cash or cash equivalents that would not ordinarily be
consistent with the Fund's objective. Of course, there is no guarantee that the
Fund will achieve its investment goal.

INVESTMENT ADVISER

Wellington Management Company, LLP ("Wellington"), serves as the Adviser to the
Fund. As of September 30, 1999, Wellington had approximately $217 billion in
assets under management. As of September 30, 1999, the Fund was no longer in
operation, and therefore did not pay an advisory fee to Wellington.

John C. Keogh is the portfolio manager of the Fund. Mr. Keogh has been an
investment professional with Wellington since 1983.

PURCHASING AND SELLING FUND SHARES

This section tells you how to purchase or sell (sometimes called "redeem")
shares of the Fund. The Fund offers Class A Shares only to financial
institutions or intermediaries for their own or their customers' accounts. For
information on how to open an account and set up procedures for placing
transactions, please call 1-800-DIAL-SEI.

HOW TO PURCHASE FUND SHARES

Financial institutions and intermediaries may purchase Class A Shares by placing
orders with the Fund's Transfer Agent (or its authorized agent). Institutions
and intermediaries that use certain SEI proprietary systems may place orders
electronically through those systems. Cash investments must be transmitted or
delivered in federal funds to the Fund's wire agent by the close of business on
the same day the order is placed. The Fund may reject any purchase order if they
determine that accepting the order would not be in the best interests of the
Fund or its shareholders.

Page 7 of 13
<PAGE>

Investors who deal directly with a financial institution or financial
intermediary will have to follow the institution's or intermediary's procedures
for transacting with the Fund. For more information about how to purchase or
sell Fund shares through your financial institution, you should contact your
financial institution directly. Investors may be charged a fee for purchase
and/or redemption transactions effectuated through certain of these
broker-dealers or other financial intermediaries.

HOW THE FUND CALCULATES NAV

NAV for one Fund share is the value of that share's portion of all of the net
assets in the Fund.

HOW TO SELL YOUR FUND SHARES

Holders of Class A Shares may sell shares on any Business Day by following the
procedures established when they opened their account or accounts with their
financial institution or intermediary. You may also sell your shares by
contacting your financial institution or financial intermediary by telephone.
Your financial institution or intermediary may charge you a fee for its
services. The sale price of each share will be the next NAV determined after the
Fund (or its authorized intermediaries) receives your request.

RECEIVING YOUR MONEY

Normally, the Fund will make payment on your sale as promptly as possible after
it receives your request, but it may take up to three Business Days. Your
proceeds will be wired to your bank account.

Page 8 of 13
<PAGE>

REDEMPTIONS IN KIND

The Fund generally pays sale (redemption) proceeds in cash. However, under
unusual conditions that make the payment of cash unwise (and for the protection
of the Fund's remaining shareholders) the Fund might pay all or part of your
redemption proceeds in liquid securities with a market value equal to the
redemption price (redemption in kind). It is highly unlikely that your shares
would ever be redeemed in kind, but if they were, you might have to pay
transaction costs to sell the securities distributed to you, as well as taxes on
any capital gains from the sale as with any redemption.

SUSPENSION OF YOUR RIGHT TO SELL YOUR SHARES

The Fund may suspend your right to sell your shares if the NYSE restricts
trading, the SEC declares an emergency or for other reasons. More information
about this is in the SAI.

DISTRIBUTION OF FUND SHARES

SEI Investments Distribution Co. (SIDCo.) is the distributor of the shares of
the Fund. SIDCo. receives no compensation for distributing the Fund's Class A
Shares.

For Class A Shares, shareholder servicing fees, as a percentage of average daily
net assets, may be up to 0.25%. The Distributor has voluntarily agreed to waive
the shareholder servicing fees applicable to Class A Shares of the Fund. The
Distributor has no current intention to discontinue this voluntary waiver.

DIVIDENDS AND DISTRIBUTIONS

The Fund declares dividends daily and distributes its income monthly. The Fund
makes distributions of capital gains, if any, at least annually.

You will receive dividends and distributions in the form cash unless otherwise
stated.

TAXES

The Fund will distribute substantially all of its income and capital gains, if
any. The dividends and distributions you receive may be subject to federal,
state and local taxation, depending upon your tax situation. If so, they are
taxable whether or not you reinvest them. Income distribution are generally
taxable at ordinary interest rates. Capital gains distributions are generally
taxable at the rates applicable to long-term capital gains. EACH SALE OF FUND
SHARES IS A TAXABLE EVENT.

MORE INFORMATION ABOUT TAXES IS IN THE FUND'S SAI.

Page 9 of 13
<PAGE>

FINANCIAL HIGHLIGHTS

The table that follows presents performance information about Class A Shares of
the Fund. This information is intended to help you understand the Fund's
financial performance for the last five years of the Fund's operations. Some of
this information reflects financial information for a single Fund share. The
total returns in the table represent the rate that you would have earned (or
lost) on an investment in a Fund, assuming you reinvested all of your dividends
and distributions.

This information has been audited by PricewaterhouseCoopers LLP independent
public accountants. Their report, along with the Fund's financial statements,
appears in the annual report that accompanies the Fund's SAI. You can obtain the
annual report, which contains more performance information, at no charge by
calling 1-800-DIAL-SEI.

Page 10 of 13
<PAGE>

FINANCIAL HIGHLIGHTS
SEI Liquid Asset Trust -- for the years ended June 30,
For a Share Outstanding Throughout each Period

DISTRIBUTIONS
NET ASSET REALIZED AND DISTRIBUTIONS FROM
VALUE NET UNREALIZED FROM NET REALIZED NET ASSET
BEGINNING INVESTMENT GAINS ON INVESTMENT CAPITAL VALUE END
OF PERIOD INCOME SECURITIES INCOME GAINS OF PERIOD
- -----------------------------------------------------------------------------------------------------------

<S> <C> <C> <C> <C> <C> <C>
INSTITUTIONAL CASH
1997 $1.00 $0.0002 -- $(0.0002) -- $1.00
1996 1.00 0.0005 -- (0.0005) -- 1.00
1995 1.00 0.0003 -- (0.0003) -- 1.00
1994 1.00 0.0003 -- (0.0003) -- 1.00
1993 1.00 0.0003 -- (0.0003) -- 1.00
<CAPTION>
RATIO OF
NET
RATIO OF RATIO OF INVESTMENT
NET EXPENSES INCOME
RATIO OF INVESTMENT TO AVERAGE TO AVERAGE
NET ASSETS EXPENSES INCOME NET ASSETS NET ASSETS
TOTAL END OF TO AVERAGE TO AVERAGE (EXCLUDING (EXCLUDING
RETURN PERIOD(000) NET ASSETS NET ASSETS WAIVERS) WAIVERS)
- -----------------------------------------------------------------------------------------------------------

<S> <C> <C> <C> <C> <C> <C>
INSTITUTI0NAL CASH
1997 3.94% -- 0.44% 3.94% 0.69% 3.69%
1996 4.58 -- 0.44 4.58 0.44 4.58
1995 4.94 -- 0.44 5.19 0.44 5.19
1994 2.60 -- 0.44 2.63 0.44 2.63
1993 2.83 -- 0.44 2.66 0.44 2.66
</TABLE>

AMOUNTS DESIGNATED AS "--" ARE EITHER $0 OR HAVE BEEN ROUNDED TO $0.

Page 11 of 13
<PAGE>

SEI LIQUID ASSET TRUST

INVESTMENT ADVISER

Wellington Management Company, LLP
75 State Street
Boston, MA 02109

DISTRIBUTOR

SEI Investments Distribution Co.
One Freedom Valley Drive
Oaks, PA 19456

LEGAL COUNSEL

Morgan, Lewis & Bockius LLP

More information about the Fund is available without charge through the
following:

STATEMENT OF ADDITIONAL INFORMATION (SAI)

ANNUAL AND SEMI-ANNUAL REPORTS

TO OBTAIN MORE INFORMATION:

BY TELEPHONE: Call 1-800-DIAL-SEI

BY MAIL: Write to the Fund at:
One Freedom Valley Drive
Oaks, PA 19456

BY INTERNET: http://www.seic.com

Page 12 of 13
<PAGE>

FROM THE SEC: You can also obtain the SAI or the Annual and Semi-Annual Reports,
as well as other information about SEI Liquid Asset Trust, from the SEC's
website ("http://www.sec.gov"). You may review and copy documents at the SEC
Public Reference Room in Washington, DC (for information call 1-800-SEC-0330).
You may request documents by mail from the SEC, upon payment of a duplicating
fee, by writing to: Securities and Exchange Commission, Public Reference
Section, Washington, DC 20549-6009.

The Fund's Investment Company Act registration number is 811-03231.

Page 13 of 13
<PAGE>

SEI
LIQUID
ASSET
TRUST
CLASS A SHARES

PROSPECTUS
OCTOBER 31, 1999

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

TREASURY SECURITIES FUND
PRIME OBLIGATION FUND
---------------------------------------------------------

ADVISER
WELLINGTON MANAGEMENT COMPANY, LLP

TREASURY SECURITIES FUND.............................................4

PRIME OBLIGATION FUND................................................6

THE FUNDS' OTHER INVESTMENTS.........................................8

THE INVESTMENT ADVISER...............................................8

PURCHASING AND SELLING FUND SHARES...................................8

DIVIDENDS AND DISTRIBUTIONS.........................................11

TAXES...............................................................11

FINANCIAL HIGHLIGHTS................................................12

HOW TO OBTAIN MORE INFORMATION ABOUT SEI LIQUID ASSET TRUST.......Back
Cover
<PAGE>
PROSPECTUS 3

RISK/RETURN INFORMATION COMMON TO THE FUNDS

Each Fund is a mutual fund. A mutual fund pools shareholders' money and, using
professional investment managers, invests it in securities.

Each Fund has its own investment goal and strategies for reaching that goal.
Each Fund's assets are managed under the direction of its Adviser. The Adviser
invests each Fund's assets in a way it believes will help each Fund achieve its
goal. Still, investing in the Funds involve risk, and there is no guarantee that
the Funds will achieve their goal. In fact, no matter how good a job the Adviser
does, you could lose money on your investment in the Funds, just as you could
with other investments. A Fund share is not a bank deposit and it is not insured
or guaranteed by the FDIC or any other government agency.