<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0001094521
<NAME> PIONEER HIGH YIELD FUND
<SERIES>
<NUMBER> 004
<NAME> PIONEER HIGH YIELD FUND CLASS Y
<CURRENCY> US
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> OCT-31-2000
<PERIOD-END> APR-30-2000
<EXCHANGE-RATE> 1
<INVESTMENTS-AT-COST> 25654539
<INVESTMENTS-AT-VALUE> 24860031
<RECEIVABLES> 1318824
<ASSETS-OTHER> 12552
<OTHER-ITEMS-ASSETS> 370737
<TOTAL-ASSETS> 26562144
<PAYABLE-FOR-SECURITIES> 1834784
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 175486
<TOTAL-LIABILITIES> 2010270
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 24847434
<SHARES-COMMON-STOCK> 8815
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 10969
<ACCUMULATED-NET-GAINS> 509917
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (794508)
<NET-ASSETS> 24551874
<DIVIDEND-INCOME> 8000
<INTEREST-INCOME> 594982
<OTHER-INCOME> 0
<EXPENSES-NET> 83141
<NET-INVESTMENT-INCOME> 519841
<REALIZED-GAINS-CURRENT> 509954
<APPREC-INCREASE-CURRENT> 293098
<NET-CHANGE-FROM-OPS> 1322893
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 1597
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 8815
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 16961201
<ACCUMULATED-NII-PRIOR> 59002
<ACCUMULATED-GAINS-PRIOR> 132686
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 49264
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 197017
<AVERAGE-NET-ASSETS> 95598
<PER-SHARE-NAV-BEGIN> 11.34
<PER-SHARE-NII> 0.18
<PER-SHARE-GAIN-APPREC> (0.45)
<PER-SHARE-DIVIDEND> 0.18
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 10.89
<EXPENSE-RATIO> 0.71
</TABLE>
