<PAGE>
AMERICAN GENERAL LIFE INSURANCE COMPANY
SEPARATE ACCOUNT D
PLATINUM INVESTOR(SM)
FLEXIBLE PAYMENT VARIABLE AND FIXED INDIVIDUAL DEFERRED ANNUITY CONTRACTS
SUPPLEMENT DATED DECEMBER 1, 2000
TO
PROSPECTUS DATED NOVEMBER 1, 2000
Effective November 29, 2000, American General Life Insurance Company is amending
the Platinum Investor Variable Annuity Prospectus for the purpose of reflecting
that the Ayco Large Cap Growth Fund I is available as a Series under the
Contracts.
. On page 1, delete the asterisk from the "Ayco Large Cap Growth Fund I" name
that appears in the list of mutual fund Series. In addition, delete the
footnote to which the asterisk refers.
. On page 9, in the table entitled The Series' Annual Expenses/1/ (as a
percentage of average net assets), the information in the table related only
to the Ayco Large Cap Growth Fund I is deleted in its entirety and replaced
with the following:
<TABLE>
<CAPTION>
Management Other Annual Expenses
Fees After Expenses After
Expense 12b-1 After Expense Expense
Series Reimbursement Fees Reimbursement Reimbursement
------ ------------- ----- ------------- ---------------
<S> <C> <C> <C> <C>
Ayco Large Cap Growth Fund I/2/..........0.80%...............................0.20%.....................1.00%
</TABLE>
. On page 9, delete footnote number two in its entirety and replace it
with the following:
"/2/Fees and charges for Ayco Large Cap Growth Fund I are for fiscal year
2000 and are the fees and charges that the Series anticipates it will
charge."
. On page 20, under SEPARATE ACCOUNT D, delete the second sentence of the first
paragraph and replace it with the following:
"The Separate Account has 93 Divisions, 41 of which are available under the
Contracts offered by this Prospectus."
. On pages 20 and 21, under THE SERIES, delete the first three paragraphs and
replace them with the following:
"The Separate Account has 41 Divisions funding the variable benefits under
the Contracts. These Divisions invest in nineteen separate Series of mutual
funds.
The mutual funds offer shares of their Series without sales charges,
exclusively to insurance company variable annuity and variable life separate
accounts and not directly to the public. The mutual funds, other than North
American Funds Variable Product Series I (formerly known as American General
Series Portfolio Company), also offer shares to variable annuity and variable
life insurance separate accounts of insurers that are not affiliated with
AGL."
