<TABLE> <S> <C>

<PAGE>

<ARTICLE> 9
<LEGEND>
THIS SCHEDULE CONTAINS FINANCIAL INFORMATION EXTRACTED FROM THE CONSOLIDATED
FINANCIAL STATEMENTS OF CONNECTICUT BANCSHARES, INC. FOR THE SIX MONTHS ENDED
JUNE 30, 2000 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL
STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

<S>                                      <C>
<PERIOD-TYPE>                             6-MOS
<FISCAL-YEAR-END>                            DEC-31-2000
<PERIOD-START>                               JAN-01-2000
<PERIOD-END>                                 JUN-30-2000
<CASH>                                            31,175
<INT-BEARING-DEPOSITS>                                 9
<FED-FUNDS-SOLD>                                  25,007
<TRADING-ASSETS>                                       0
<INVESTMENTS-HELD-FOR-SALE>                            0
<INVESTMENTS-CARRYING>                           295,504
<INVESTMENTS-MARKET>                             311,939
<LOANS>                                          995,239
<ALLOWANCE>                                       11,158
<TOTAL-ASSETS>                                 1,388,227
<DEPOSITS>                                       918,751
<SHORT-TERM>                                     114,778
<LIABILITIES-OTHER>                                9,571
<LONG-TERM>                                      114,000
<PREFERRED-MANDATORY>                                  0
<PREFERRED>                                            0
<COMMON>                                             112
<OTHER-SE>                                       220,883
<TOTAL-LIABILITIES-AND-EQUITY>                 1,388,227
<INTEREST-LOAN>                                   36,734
<INTEREST-INVEST>                                  8,733
<INTEREST-OTHER>                                       0
<INTEREST-TOTAL>                                  45,467
<INTEREST-DEPOSIT>                                18,212
<INTEREST-EXPENSE>                                21,180
<INTEREST-INCOME-NET>                             24,287
<LOAN-LOSSES>                                        450
<SECURITIES-GAINS>                                (1,784)
<EXPENSE-OTHER>                                   28,466
<INCOME-PRETAX>                                   (1,687)
<INCOME-PRE-EXTRAORDINARY>                        (1,687)
<EXTRAORDINARY>                                        0
<CHANGES>                                              0
<NET-INCOME>                                      (1,134)
<EPS-BASIC>                                         0.31
<EPS-DILUTED>                                       0.31
<YIELD-ACTUAL>                                      7.15
<LOANS-NON>                                        8,008
<LOANS-PAST>                                         646
<LOANS-TROUBLED>                                       0
<LOANS-PROBLEM>                                        0
<ALLOWANCE-OPEN>                                  10,617
<CHARGE-OFFS>                                        110
<RECOVERIES>                                         201
<ALLOWANCE-CLOSE>                                 11,158
<ALLOWANCE-DOMESTIC>                              11,158
<ALLOWANCE-FOREIGN>                                    0
<ALLOWANCE-UNALLOCATED>                           11,158


</TABLE>