<ARTICLE>                                            9
<LEGEND>
         This schedule contains summary financial information extracted from the
unaudited financial statements of SIS Bancorp,  Inc. at and for the period ended
June 30, 1998 and is qualified  in its  entirety by reference to such  financial
statements.
</LEGEND>
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                              DEC-31-1998
<PERIOD-START>                                 JAN-01-1998
<PERIOD-END>                                   JUN-30-1998
<CASH>                                         56,578
<INT-BEARING-DEPOSITS>                         19,865
<FED-FUNDS-SOLD>                               22,900
<TRADING-ASSETS>                               0
<INVESTMENTS-HELD-FOR-SALE>                    566,945
<INVESTMENTS-CARRYING>                         233,767
<INVESTMENTS-MARKET>                           234,404
<LOANS>                                        870,145
<ALLOWANCE>                                    23,482
<TOTAL-ASSETS>                                 1,841,662
<DEPOSITS>                                     1,326,895
<SHORT-TERM>                                   333,728
<LIABILITIES-OTHER>                            47,188
<LONG-TERM>                                    2,314
<PREFERRED-MANDATORY>                          0
<PREFERRED>                                    0
<COMMON>                                       71
<OTHER-SE>                                     131,466
<TOTAL-LIABILITIES-AND-EQUITY>                 1,841,662
<INTEREST-LOAN>                                36,029
<INTEREST-INVEST>                              24,107
<INTEREST-OTHER>                               1,091
<INTEREST-TOTAL>                               61,227
<INTEREST-DEPOSIT>                             21,569
<INTEREST-EXPENSE>                             30,591
<INTEREST-INCOME-NET>                          30,636
<LOAN-LOSSES>                                  503
<SECURITIES-GAINS>                             2
<EXPENSE-OTHER>                                25,249
<INCOME-PRETAX>                                13,389
<INCOME-PRE-EXTRAORDINARY>                     13,389
<EXTRAORDINARY>                                0
<CHANGES>                                      0
<NET-INCOME>                                   8,301
<EPS-PRIMARY>                                  1.24
<EPS-DILUTED>                                  1.17
<YIELD-ACTUAL>                                 7.38
<LOANS-NON>                                    3,598
<LOANS-PAST>                                   109
<LOANS-TROUBLED>                               433
<LOANS-PROBLEM>                                17,658
<ALLOWANCE-OPEN>                               22,724
<CHARGE-OFFS>                                  717
<RECOVERIES>                                   972
<ALLOWANCE-CLOSE>                              23,482
<ALLOWANCE-DOMESTIC>                           23,482
<ALLOWANCE-FOREIGN>                            0
<ALLOWANCE-UNALLOCATED>                        0