EXHIBIT 11 BANK OF BOSTON CORPORATION COMPUTATION OF EARNINGS PER COMMON SHARE (IN MILLIONS, EXCEPT SHARES AND PER SHARE AMOUNTS) QUARTERS ENDED NINE MONTHS ENDED SEPTEMBER 30 SEPTEMBER 30 --------------- ----------------- 1995 1994 1995 1994 ------- ------- -------- -------- EARNINGS 1. Net income............................... $140 $124 $399 $315 2. Less: Preferred dividends................ 9 9 28 28 ------- ------- -------- -------- 3. Net income applicable to primary earnings per common share.......................... 131 115 371 287 4. Add: Interest expense on convertible debentures, net of tax.................... 1 3 ------- ------- -------- -------- 5. Net income applicable to fully diluted earnings per common share................. $131 $116 $371 $290 ======= ======= ======== ======== SHARES (in thousands) 6. Weighted average number of common shares outstanding............................... 111,865 106,981 110,188 106,602 7. Incremental shares from assumed exercise of dilutive stock options as of the beginning of the period using the treasury stock method.............................. 1,938 680 2,089 759 8. Incremental shares from assumed conversion of debentures at date of issuance.................................. 4,029 1,181 4,030 ------- ------- -------- -------- 9. Adjusted number of common shares......... 113,803 111,690 113,458 111,391 ======= ======= ======== ======== PER SHARE CALCULATION 10. Primary net income per common share (Item 3 / Item 6)............................... $1.17 $1.07 $3.36 $2.69 11. Fully diluted net income per common share (Item 5 / Item 9)......................... $1.15 $1.04 $3.27 $2.60 Note--Income per common share before extraordinary items, net of tax, on both a primary and fully diluted basis for the nine months ended September 30, 1994 is computed by adding $7 million to the numerator.