Exhibit 11 STATE STREET BOSTON CORPORATION COMPUTATION OF EARNINGS PER SHARE (Dollars in thousands, Three Months Ended Nine Months Ended except per share data) September 30, September 30, ---------------------------- ---------------------------- 1995 1994 1995 1994 ---------- ---------- ---------- ---------- Primary Average shares outstanding 82,646,403 82,425,243 82,577,988 82,247,166 Common stock equivalents 525,630 532,409 457,367 566,500 ---------- ---------- ---------- ---------- Primary shares outstanding 83,172,033 82,957,652 83,035,355 82,813,666 ========== ========== ========== ========== Net income $ 64,636 $ 55,153 $ 181,633 $ 163,229 ========== ========== ========== ========== Earnings Per Share-primary $ .78 $ .66 $ 2.19 $ 1.97 ========== ========== ========== ========== Fully Diluted Average shares outstanding 82,646,403 82,425,243 82,577,988 82,247,166 Common stock equivalents 697,682 532,409 637,643 566,500 Assumed conversion of 7 3/4% convertible subordinated debentures 566,856 585,739 576,063 646,485 ---------- ---------- ---------- ---------- Fully diluted average shares outstanding 83,910,941 83,543,391 83,791,694 83,460,151 ========== ========== ========== ========== Net income $ 64,636 $ 55,153 $ 181,633 $ 163,229 Elimination of interest on 7 3/4% convertible subordinated debentures and 5% convertible notes less related income tax effect 36 37 111 118 ---------- ---------- ---------- ---------- Fully diluted net income $ 64,672 $ 5,190 $ 181,744 $ 163,347 ========== ========== ========== ========== Earnings Per Share-fully diluted $ .77 $ 0.66 $ 2.17 $ 1.96 ========== ========== ========== ==========