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<PAGE> PAGE 2
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<PAGE> PAGE 3
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<PAGE> PAGE 4
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<PAGE> PAGE 5
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<PAGE> PAGE 7
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<PAGE> PAGE 8
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<PAGE> PAGE 9
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<PAGE> PAGE 10
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<PAGE> PAGE 11
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<PAGE> PAGE 12
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<PAGE> PAGE 13
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<PAGE> PAGE 14
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<PAGE> PAGE 15
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<PAGE> PAGE 16
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<PAGE> PAGE 17
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<PAGE> PAGE 18
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<PAGE> PAGE 19
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<PAGE> PAGE 20
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<PAGE> PAGE 21
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075 A000500 164261
075 B000500 0
076 000500 0.00
SIGNATURE PAUL JASINSKI
TITLE TREASURER
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 001
<NAME> Merrimac Cash Series Premium Class
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 272,234,113
<INVESTMENTS-AT-VALUE> 272,234,113
<RECEIVABLES> 0
<ASSETS-OTHER> 9,550
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 272,243,663
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1,352,960
<TOTAL-LIABILITIES> 1,352,960
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 270,901,782
<SHARES-COMMON-STOCK> 22,685,825
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (527)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 22,685,298
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 383,064
<OTHER-INCOME> 0
<EXPENSES-NET> 18,775
<NET-INVESTMENT-INCOME> 364,289
<REALIZED-GAINS-CURRENT> (530)
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 363,759
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 364,289
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 57,762,564
<NUMBER-OF-SHARES-REDEEMED> 35,366,387
<SHARES-REINVESTED> 189,648
<NET-CHANGE-IN-ASSETS> 22,585,825
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 565,229
<AVERAGE-NET-ASSETS> 15,146,802
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.02)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.25
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 002
<NAME> Merrimac Cash Series Institutional Class
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 272,234,113
<INVESTMENTS-AT-VALUE> 272,234,113
<RECEIVABLES> 0
<ASSETS-OTHER> 9,550
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 272,243,663
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1,352,960
<TOTAL-LIABILITIES> 1,352,960
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 270,901,782
<SHARES-COMMON-STOCK> 248,215,957
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (10,552)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 248,205,405
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 5,615,489
<OTHER-INCOME> 0
<EXPENSES-NET> 546,454
<NET-INVESTMENT-INCOME> 5,069,035
<REALIZED-GAINS-CURRENT> (14,258)
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 5,054,777
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 5,069,035
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 612,550,420
<NUMBER-OF-SHARES-REDEEMED> 479,468,200
<SHARES-REINVESTED> 10,337
<NET-CHANGE-IN-ASSETS> 133,092,557
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 565,229
<AVERAGE-NET-ASSETS> 220,390,156
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.02)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.50
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 004
<NAME> Merrimac Treasury Series Premium Class
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 208,139,956
<INVESTMENTS-AT-VALUE> 208,139,956
<RECEIVABLES> 0
<ASSETS-OTHER> 7,560
<OTHER-ITEMS-ASSETS> 3,500
<TOTAL-ASSETS> 208,151,016
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 772,465
<TOTAL-LIABILITIES> 772,465
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 207,373,113
<SHARES-COMMON-STOCK> 22,521,868
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 212
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 22,522,080
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 580,729
<OTHER-INCOME> 0
<EXPENSES-NET> 36,848
<NET-INVESTMENT-INCOME> 543,881
<REALIZED-GAINS-CURRENT> 213
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 544,094
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 543,881
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 72,173,800
<NUMBER-OF-SHARES-REDEEMED> 49,651,932
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 22,521,868
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 429,569
<AVERAGE-NET-ASSETS> 35,134,922
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.02)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.29
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 005
<NAME> Merrimac Treasury Series Institutional Cla
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 208,139,956
<INVESTMENTS-AT-VALUE> 208,139,956
<RECEIVABLES> 0
<ASSETS-OTHER> 7,560
<OTHER-ITEMS-ASSETS> 3,500
<TOTAL-ASSETS> 208,151,016
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 772,465
<TOTAL-LIABILITIES> 772,465
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 207,373,113
<SHARES-COMMON-STOCK> 184,851,245
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 2,087
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 184,853,332
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 3,311,977
<OTHER-INCOME> 0
<EXPENSES-NET> 392,721
<NET-INVESTMENT-INCOME> 2,919,256
<REALIZED-GAINS-CURRENT> 817
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 2,920,073
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 2,919,256
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 358,609,627
<NUMBER-OF-SHARES-REDEEMED> 288,078,569
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 70,531,058
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 429,569
<AVERAGE-NET-ASSETS> 146,427,346
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.02)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.54
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 7
<NAME> Merrimac STAR Series Premium Class
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 0
<INVESTMENTS-AT-VALUE> 0
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 0
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 0
<TOTAL-LIABILITIES> 0
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 0
<SHARES-COMMON-STOCK> 0
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 0
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 24,438
<OTHER-INCOME> 0
<EXPENSES-NET> 1,486
<NET-INVESTMENT-INCOME> 22,952
<REALIZED-GAINS-CURRENT> (6,713)
<APPREC-INCREASE-CURRENT> 3,715
<NET-CHANGE-FROM-OPS> 19,954
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 22,820
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 0
<NUMBER-OF-SHARES-REDEEMED> 1,039,437
<SHARES-REINVESTED> 34,416
<NET-CHANGE-IN-ASSETS> (1,005,021)
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 16,874
<AVERAGE-NET-ASSETS> 1,031,389
<PER-SHARE-NAV-BEGIN> 9.97
<PER-SHARE-NII> 0.22
<PER-SHARE-GAIN-APPREC> (0.03)
<PER-SHARE-DIVIDEND> (0.24)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 9.93
<EXPENSE-RATIO> 0.36
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 011
<NAME> Merrimac Treasury Plus Series Institutiona
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 231,025,568
<INVESTMENTS-AT-VALUE> 231,025,568
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 231,025,568
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 987,586
<TOTAL-LIABILITIES> 987,586
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 230,038,048
<SHARES-COMMON-STOCK> 230,038,048
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (66)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 230,037,982
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 4,971,411
<OTHER-INCOME> 0
<EXPENSES-NET> 527,394
<NET-INVESTMENT-INCOME> 4,444,017
<REALIZED-GAINS-CURRENT> (66)
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 4,443,951
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 4,444,017
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 620,522,252
<NUMBER-OF-SHARES-REDEEMED> 390,484,204
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 230,038,048
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 527,394
<AVERAGE-NET-ASSETS> 239,348,448
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.02)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.50
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 015
<NAME> Merrimac U.S. Government Series Institutio
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 169,412,124
<INVESTMENTS-AT-VALUE> 169,412,124
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 169,412,124
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 42,718
<TOTAL-LIABILITIES> 42,718
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 169,369,406
<SHARES-COMMON-STOCK> 169,369,406
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 169,369,406
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 44,698
<OTHER-INCOME> 0
<EXPENSES-NET> 5,220
<NET-INVESTMENT-INCOME> 39,478
<REALIZED-GAINS-CURRENT> 0
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 39,478
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 39,478
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 169,369,406
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 169,369,406
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 5,220
<AVERAGE-NET-ASSETS> 164,260,861
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.00
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.00)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.58
</TABLE>
