<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000804239
<NAME> SEI INSTITUTIONAL MANAGED TRUST
<SERIES>
<NUMBER> 090
<NAME> MID-CAP 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> 38296
<INVESTMENTS-AT-VALUE> 42022
<RECEIVABLES> 0
<ASSETS-OTHER> 126
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 42148
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 0
<TOTAL-LIABILITIES> 0
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 33404
<SHARES-COMMON-STOCK> 2420
<SHARES-COMMON-PRIOR> 2304
<ACCUMULATED-NII-CURRENT> 32
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 4986
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 3726
<NET-ASSETS> 42148
<DIVIDEND-INCOME> 530
<INTEREST-INCOME> 27
<OTHER-INCOME> 01
<EXPENSES-NET> (377)
<NET-INVESTMENT-INCOME> 180
<REALIZED-GAINS-CURRENT> 5452
<APPREC-INCREASE-CURRENT> 3233
<NET-CHANGE-FROM-OPS> 8865
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (173)
<DISTRIBUTIONS-OF-GAINS> (3370)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 1124
<NUMBER-OF-SHARES-REDEEMED> (1184)
<SHARES-REINVESTED> 176
<NET-CHANGE-IN-ASSETS> 7153
<ACCUMULATED-NII-PRIOR> 25
<ACCUMULATED-GAINS-PRIOR> 29004
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 151
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 396
<AVERAGE-NET-ASSETS> 37642
<PER-SHARE-NAV-BEGIN> 15.19
<PER-SHARE-NII> 0.07
<PER-SHARE-GAIN-APPREC> 3.76
<PER-SHARE-DIVIDEND> (0.07)
<PER-SHARE-DISTRIBUTIONS> (1.53)
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 17.42
<EXPENSE-RATIO> 1.00
</TABLE>
