<PAGE>
SEI ASSET ALLOCATION TRUST
DIVERSIFIED CONSERVATIVE INCOME FUND
DIVERSIFIED CONSERVATIVE FUND
DIVERSIFIED GLOBAL MODERATE GROWTH FUND
DIVERSIFIED MODERATE GROWTH FUND
DIVERSIFIED GLOBAL GROWTH FUND
DIVERSIFIED GLOBAL STOCK FUND
DIVERSIFIED U.S. STOCK FUND
SUPPLEMENT DATED OCTOBER 18, 1999, TO THE
CLASS A PROSPECTUS DATED JULY 31, 1999.
THIS SUPPLEMENT PROVIDES NEW AND ADDITIONAL INFORMATION BEYOND THAT CONTAINED IN
THE PROSPECTUS. IT SHOULD BE RETAINED AND READ IN CONJUNCTION WITH SUCH
PROSPECTUS.
DIVERSIFIED CONSERVATIVE INCOME FUND
The performance bar chart on page 3 should be replaced with the following:
EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC
<TABLE>
<CAPTION>
1997 13.85%
<S> <C>
1998 11.33%
</TABLE>
The footnote to the bar chart on page 3 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 2.21%.
DIVERSIFIED CONSERVATIVE FUND
The footnote to the bar chart on page 5 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 2.09%.
In the table on page 5, the Since Inception percentage for the Wilshire 5000
Index should be replaced with the following: 25.98%.
DIVERSIFIED GLOBAL MODERATE GROWTH FUND
The footnote to the bar chart on page 7 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 7.93%.
DIVERSIFIED MODERATE GROWTH FUND
The footnote to the bar chart on page 9 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 5.18%.
In the table on page 9, the Since Inception percentage for the Wilshire 5000
Index should be replaced with the following: 25.98%.
<PAGE>
DIVERSIFIED GLOBAL GROWTH FUND
The footnote to the bar chart on page 11 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 10.87%.
DIVERSIFIED GLOBAL STOCK FUND
The footnote to the bar chart on page 13 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 13.89%.
DIVERSIFIED U.S. STOCK FUND
The footnote to the bar chart on page 15 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS A TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 12.02%.
The prospectus is hereby amended to reflect these changes.
--------------------------
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.
<PAGE>
SEI ASSET ALLOCATION TRUST
DIVERSIFIED CONSERVATIVE INCOME FUND
DIVERSIFIED CONSERVATIVE FUND
DIVERSIFIED GLOBAL MODERATE GROWTH FUND
DIVERSIFIED MODERATE GROWTH FUND
DIVERSIFIED GLOBAL GROWTH FUND
DIVERSIFIED GLOBAL STOCK FUND
DIVERSIFIED U.S. STOCK FUND
SUPPLEMENT DATED OCTOBER 18, 1999, TO THE
CLASS D PROSPECTUS DATED JULY 31, 1999.
THIS SUPPLEMENT PROVIDES NEW AND ADDITIONAL INFORMATION BEYOND THAT CONTAINED IN
THE PROSPECTUS. IT SHOULD BE RETAINED AND READ IN CONJUNCTION WITH SUCH
PROSPECTUS.
DIVERSIFIED CONSERVATIVE INCOME FUND
The performance bar chart on page 3 should be replaced with the following:
EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC
<TABLE>
<CAPTION>
1997 12.76%
<S> <C>
1998 10.35%
</TABLE>
The footnote to the bar chart on page 3 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 1.63%.
DIVERSIFIED CONSERVATIVE FUND
The footnote to the bar chart on page 5 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 1.50%.
In the table on page 5, the One Year and Since Inception percentages for the
Diversified Conservative Fund should be replaced with the following: 14.58% and
13.61%.
DIVERSIFIED GLOBAL MODERATE GROWTH FUND
The footnote to the bar chart on page 7 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 7.39%.
DIVERSIFIED MODERATE GROWTH FUND
The footnote to the bar chart on page 9 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 4.71%.
<PAGE>
DIVERSIFIED GLOBAL GROWTH FUND
The footnote to the bar chart on page 11 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 9.32%.
DIVERSIFIED GLOBAL STOCK FUND
The footnote to the bar chart on page 13 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 13.32%.
DIVERSIFIED U.S. STOCK FUND
The footnote to the bar chart on page 15 should be replaced with the following:
* THE PERFORMANCE INFORMATION SHOWN ABOVE IS BASED ON A CALENDAR YEAR. THE
FUND'S CLASS D TOTAL RETURN FROM JANUARY 1, 1999, TO JUNE 30, 1999, WAS 11.50%.
The prospectus is hereby amended to reflect these changes.
--------------------------
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.
