WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000746714
<NAME> MUNDER INSTITUTIONAL INDEX 500 FUND
<SERIES>
<NUMBER> 064
<NAME> CLASS K
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-START> JAN-01-2000
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 117870070
<INVESTMENTS-AT-VALUE> 124723897
<RECEIVABLES> 2531838
<ASSETS-OTHER> 22142
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 127277877
<PAYABLE-FOR-SECURITIES> 3327457
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 101470
<TOTAL-LIABILITIES> 3428927
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 101029424
<SHARES-COMMON-STOCK> 1729416
<SHARES-COMMON-PRIOR> 399467
<ACCUMULATED-NII-CURRENT> 19405
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 15944730
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 6855391
<NET-ASSETS> 123848950
<DIVIDEND-INCOME> 761783
<INTEREST-INCOME> 80575
<OTHER-INCOME> 0
<EXPENSES-NET> (72403)
<NET-INVESTMENT-INCOME> 769955
<REALIZED-GAINS-CURRENT> 16013731
<APPREC-INCREASE-CURRENT> (19908057)
<NET-CHANGE-FROM-OPS> (3124371)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (78526)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 1448312
<NUMBER-OF-SHARES-REDEEMED> (118371)
<SHARES-REINVESTED> 8
<NET-CHANGE-IN-ASSETS> 875969
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> (69001)
<GROSS-ADVISORY-FEES> 47000
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 190000
<AVERAGE-NET-ASSETS> 9534000
<PER-SHARE-NAV-BEGIN> 10.54
<PER-SHARE-NII> 0.05
<PER-SHARE-GAIN-APPREC> 0.12
<PER-SHARE-DIVIDEND> (0.06)
<PER-SHARE-DISTRIBUTIONS> (0.23)
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.42
<EXPENSE-RATIO> 0.34
[AVG-DEBT-OUTSTANDING] 0
[AVG-DEBT-PER-SHARE] 0
</TABLE>