<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED FINANCIAL STATEMENTS OF CMGI, INC. FOR THE QUARTER ENDED APRIL 30,
2000 AS SET FORTH IN ITS FORM 10-Q FOR SUCH QUARTER AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> JUL-31-2000
<PERIOD-START> AUG-01-1999
<PERIOD-END> APR-30-2000
<CASH> 674,288
<SECURITIES> 1,381,481
<RECEIVABLES> 213,576
<ALLOWANCES> 0
<INVENTORY> 40,209
<CURRENT-ASSETS> 2,364,877
<PP&E> 219,894
<DEPRECIATION> 0
<TOTAL-ASSETS> 8,939,371
<CURRENT-LIABILITIES> 1,460,638
<BONDS> 0
381,250
0
<COMMON> 2,933
<OTHER-SE> 6,237,953
<TOTAL-LIABILITY-AND-EQUITY> 8,939,731
<SALES> 503,078
<TOTAL-REVENUES> 503,078
<CGS> 410,974
<TOTAL-COSTS> 410,974
<OTHER-EXPENSES> 1,494,070
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 26,517
<INCOME-PRETAX> (802,446)
<INCOME-TAX> (71,420)
<INCOME-CONTINUING> (731,026)
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> (731,026)
<EPS-BASIC> (2.94)
<EPS-DILUTED> (2.94)
</TABLE>