<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000741375
<NAME> MAS FUNDS
<SERIES>
<NUMBER> 022
<NAME> FIXED INCOME PORTFOLIO, INVESTMENT CLASS
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 12-MOS
<FISCAL-YEAR-END> SEP-30-2000
<PERIOD-START> OCT-01-1999
<PERIOD-END> SEP-30-2000
<INVESTMENTS-AT-COST> 6,143,108
<INVESTMENTS-AT-VALUE> 6,039,963
<RECEIVABLES> 544,553
<ASSETS-OTHER> 384
<OTHER-ITEMS-ASSETS> 266,257
<TOTAL-ASSETS> 6,851,157
<PAYABLE-FOR-SECURITIES> 2,279,494
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 275,412
<TOTAL-LIABILITIES> 2,554,906
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 4,496,456
<SHARES-COMMON-STOCK> 5,682
<SHARES-COMMON-PRIOR> 3,476
<ACCUMULATED-NII-CURRENT> 83,032
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (194,405)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (88,832)
<NET-ASSETS> 4,296,251
<DIVIDEND-INCOME> 3,652
<INTEREST-INCOME> 335,049
<OTHER-INCOME> 0
<EXPENSES-NET> (21,699)
<NET-INVESTMENT-INCOME> 317,002
<REALIZED-GAINS-CURRENT> (95,763)
<APPREC-INCREASE-CURRENT> (88,079)
<NET-CHANGE-FROM-OPS> 309,318
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (3,205)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,884
<NUMBER-OF-SHARES-REDEEMED> (914)
<SHARES-REINVESTED> 237
<NET-CHANGE-IN-ASSETS> (223,562)
<ACCUMULATED-NII-PRIOR> 82,491
<ACCUMULATED-GAINS-PRIOR> (118,367)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 16,928
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 21,897
<AVERAGE-NET-ASSETS> 4,514,844
<PER-SHARE-NAV-BEGIN> 11.27
<PER-SHARE-NII> 0.76
<PER-SHARE-GAIN-APPREC> (0.03)
<PER-SHARE-DIVIDEND> (0.75)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 11.25
<EXPENSE-RATIO> 0.63
</TABLE>
