<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,
1998, AND THE RELATED STATEMENTS OF INCOME, CHANGES IN SHAREHOLDERS' EQUITY AND
CASH FLOWS FOR THE PERIOD ENDING SEPTEMBER 30, 1998 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-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               SEP-30-1998
<CASH>                                          20,127
<INT-BEARING-DEPOSITS>                           5,005
<FED-FUNDS-SOLD>                                32,130
<TRADING-ASSETS>                                     0
<INVESTMENTS-HELD-FOR-SALE>                     74,787
<INVESTMENTS-CARRYING>                         120,823
<INVESTMENTS-MARKET>                           121,590
<LOANS>                                        301,972
<ALLOWANCE>                                      4,663
<TOTAL-ASSETS>                                 492,229
<DEPOSITS>                                     424,434
<SHORT-TERM>                                         0
<LIABILITIES-OTHER>                             22,790
<LONG-TERM>                                          0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         8,144
<OTHER-SE>                                      36,861
<TOTAL-LIABILITIES-AND-EQUITY>                 492,229
<INTEREST-LOAN>                                 20,789
<INTEREST-INVEST>                                5,064
<INTEREST-OTHER>                                 1,535
<INTEREST-TOTAL>                                27,388
<INTEREST-DEPOSIT>                               9,500
<INTEREST-EXPENSE>                               9,996
<INTEREST-INCOME-NET>                           17,392
<LOAN-LOSSES>                                      539
<SECURITIES-GAINS>                                   0
<EXPENSE-OTHER>                                 10,481
<INCOME-PRETAX>                                  9,111
<INCOME-PRE-EXTRAORDINARY>                       5,962
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     5,962
<EPS-PRIMARY>                                      .92
<EPS-DILUTED>                                      .87
<YIELD-ACTUAL>                                    5.34
<LOANS-NON>                                      6,213
<LOANS-PAST>                                         0
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                 11,524
<ALLOWANCE-OPEN>                                 4,065
<CHARGE-OFFS>                                      139
<RECOVERIES>                                       198
<ALLOWANCE-CLOSE>                                4,663
<ALLOWANCE-DOMESTIC>                             4,663
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                              0
        

</TABLE>