EXHIBIT 11 BANKBOSTON CORPORATION Computation of Earnings Per Common Share Quarters Ended Nine Months Ended September 30 September 30 ------------------ ------------------ EARNINGS (in millions) 1997 1996 1997 1996 - -------- ---------- ---------- ---------- ---------- 1. Net income $ 226 $ 80 $ 645 $ 449 2. Less: preferred dividends 9 9 27 28 -------- -------- -------- -------- 3. Net income applicable to primary and fully diluted earnings per common share $ 217 $ 71 $ 618 $ 421 ======== ======== ======== ======== SHARES (in thousands) ------ 4. Weighted average number of common shares outstanding 145,383 153,103 148,875 153,715 5. Incremental shares from assumed exercise of dilutive stock options as of the beginning of the period using the treasury stock method 2,459 2,080 2,699 2,585 -------- -------- -------- -------- 7. Adjusted number of common shares 147,842 155,183 151,574 156,300 ======== ======== ======== ======== PER SHARE CALCULATION --------------------- 8. Primary net income per common share (item 3 divided by Item 4) $ 1.49 $ .46 $ 4.15 $ 2.74 9. Primary net income per common share (item 3 divided by Item 7) $ 1.47 $ .45 $ 4.07 $ 2.69