WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000862021
<NAME> ACM INSTITUTIONAL RESERVES
<SERIES>
<NUMBER> 011
<NAME> PRIME PORTFOLIO
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> APR-30-2001
<PERIOD-START> MAY-01-2000
<PERIOD-END> OCT-31-2000
<INVESTMENTS-AT-COST> 4,719,728,081
<INVESTMENTS-AT-VALUE> 4,719,728,081
<RECEIVABLES> 25,759,258
<ASSETS-OTHER> 4,922,699
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 4,750,410,038
<PAYABLE-FOR-SECURITIES> 104,729,167
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 4,530,130
<TOTAL-LIABILITIES> 109,259,297
<SENIOR-EQUITY> 46,412,450
<PAID-IN-CAPITAL-COMMON> 4,594,832,536
<SHARES-COMMON-STOCK> 2,416,922,715
<SHARES-COMMON-PRIOR> 1,788,445,395
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (94,245)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 4,641,150,741
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 134,523,350
<OTHER-INCOME> 0
<EXPENSES-NET> (5,138,974)
<NET-INVESTMENT-INCOME> 129,384,376
<REALIZED-GAINS-CURRENT> 12,914
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 127,397,290
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (69,478,114)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 8,841,243,801
<NUMBER-OF-SHARES-REDEEMED> (8,282,244,595)
<SHARES-REINVESTED> 69,478,114
<NET-CHANGE-IN-ASSETS> 826,209,581
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (107,159)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 4,070,000
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 5,631,000
<AVERAGE-NET-ASSETS> 2,148,617,112
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.03
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> (0.03)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> .20
[AVG-DEBT-OUTSTANDING] 0
[AVG-DEBT-PER-SHARE] 0
</TABLE>
