<TABLE> <S> <C>

<PAGE>
<ARTICLE> 9
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED BALANCE SHEETS OF SUMMIT BANCSHARES, INC., AS OF SEPTEMBER 30,
1997, AND THE RELATED STATEMENTS OF INCOME, CHANGES IN SHAREHOLDERS' EQUITY AND
CASH FLOWS FOR THE PERIOD ENDING SEPTEMBER 30, 1997 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>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               SEP-30-1997
<CASH>                                          33,060
<INT-BEARING-DEPOSITS>                               0
<FED-FUNDS-SOLD>                                23,485
<TRADING-ASSETS>                                     0
<INVESTMENTS-HELD-FOR-SALE>                     58,595
<INVESTMENTS-CARRYING>                         106,307
<INVESTMENTS-MARKET>                           106,503
<LOANS>                                        262,784
<ALLOWANCE>                                      3,682
<TOTAL-ASSETS>                                 436,198
<DEPOSITS>                                     384,223
<SHORT-TERM>                                         0
<LIABILITIES-OTHER>                             12,448
<LONG-TERM>                                          0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         4,055
<OTHER-SE>                                      35,472
<TOTAL-LIABILITIES-AND-EQUITY>                 436,198
<INTEREST-LOAN>                                 17,594
<INTEREST-INVEST>                                5,258
<INTEREST-OTHER>                                   593
<INTEREST-TOTAL>                                23,445
<INTEREST-DEPOSIT>                               7,836
<INTEREST-EXPENSE>                               8,205
<INTEREST-INCOME-NET>                           15,240
<LOAN-LOSSES>                                      633
<SECURITIES-GAINS>                                  (1)
<EXPENSE-OTHER>                                  9,050
<INCOME-PRETAX>                                  7,964
<INCOME-PRE-EXTRAORDINARY>                       5,226
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     5,226
<EPS-PRIMARY>                                     1.61
<EPS-DILUTED>                                     1.61
<YIELD-ACTUAL>                                    5.50
<LOANS-NON>                                      1,245
<LOANS-PAST>                                         0
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                  7,896
<ALLOWANCE-OPEN>                                 2,972
<CHARGE-OFFS>                                      200
<RECOVERIES>                                       277
<ALLOWANCE-CLOSE>                                3,682
<ALLOWANCE-DOMESTIC>                             3,682
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                              0
        

</TABLE>