<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000804239
<NAME> SEI INSTITUTIONAL MANAGED TRUST
<SERIES>
<NUMBER> 100
<NAME> LARGE CAP GROWTH FUND
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> SEP-30-2000
<PERIOD-START> OCT-01-1999
<PERIOD-END> SEP-30-2000
<INVESTMENTS-AT-COST> 3577714
<INVESTMENTS-AT-VALUE> 4907904
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 4907904
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 9854
<TOTAL-LIABILITIES> 9854
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 3377939
<SHARES-COMMON-STOCK> 135156
<SHARES-COMMON-PRIOR> 91918
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 190075
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1330036
<NET-ASSETS> 4898050
<DIVIDEND-INCOME> 13782
<INTEREST-INCOME> 7114
<OTHER-INCOME> 0
<EXPENSES-NET> (33486)
<NET-INVESTMENT-INCOME> (12590)
<REALIZED-GAINS-CURRENT> 237913
<APPREC-INCREASE-CURRENT> 615141
<NET-CHANGE-FROM-OPS> 840464
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> (93509)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 695014
<NUMBER-OF-SHARES-REDEEMED> (28933)
<SHARES-REINVESTED> 2673
<NET-CHANGE-IN-ASSETS> 2271243
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 84571
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 15758
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 40261
<AVERAGE-NET-ASSETS> 3937425027
<PER-SHARE-NAV-BEGIN> 28.58
<PER-SHARE-NII> (0.04)
<PER-SHARE-GAIN-APPREC> 8.67
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> (0.97)
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 36.24
<EXPENSE-RATIO> 0.85
</TABLE>
