<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000804239
<NAME> SEI INSTITUTIONAL MANAGED TRUST
<SERIES>
<NUMBER> 081
<NAME> SMALL CAP GROWTH FUND - CLASS D
<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> 1331052
<INVESTMENTS-AT-VALUE> 1565155
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 14637
<TOTAL-ASSETS> 1579792
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 0
<TOTAL-LIABILITIES> 0
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 993328
<SHARES-COMMON-STOCK> 146
<SHARES-COMMON-PRIOR> 146
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 352979
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 233485
<NET-ASSETS> 1579792
<DIVIDEND-INCOME> 984
<INTEREST-INCOME> 4010
<OTHER-INCOME> 0
<EXPENSES-NET> (15335)
<NET-INVESTMENT-INCOME> (10341)
<REALIZED-GAINS-CURRENT> 497728
<APPREC-INCREASE-CURRENT> 50025
<NET-CHANGE-FROM-OPS> 537412
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> (213)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 44
<NUMBER-OF-SHARES-REDEEMED> (24)
<SHARES-REINVESTED> 9
<NET-CHANGE-IN-ASSETS> 1916
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 72083
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 9056
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 17630
<AVERAGE-NET-ASSETS> 1392524
<PER-SHARE-NAV-BEGIN> 20.63
<PER-SHARE-NII> 0.29
<PER-SHARE-GAIN-APPREC> 10.63
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> (1.82)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 29.73
<EXPENSE-RATIO> 1.35
</TABLE>