Exhibit 11 Morgan Stanley Dean Witter & Co. Computation of Earnings Per Share (in millions, except share and per share data) Three Months Ended Six Months Ended ------------------------------ ----------------------------- May 31, May 31, May 31, May 31, 2001 2000 2001 2000 ------------- ------------- ------------- ------------- Basic: Weighted-average common shares outstanding 1,085,305,558 1,098,245,490 1,087,205,706 1,096,007,767 ============= ============= ============= ============= Earnings: Income before cumulative effect of accounting change $930 $1,458 $2,005 $3,002 Cumulative effect of accounting change -- -- (59) -- Less: Preferred stock dividend requirements (9) (9) (18) (18) ------------- ------------- ------------- ------------- Earnings applicable to common shares $921 $1,449 $1,928 $2,984 ============= ============= ============= ============= Basic EPS before cumulative effect of accounting change $0.85 $1.32 $1.83 $2.72 Cumulative effect of accounting change -- -- (0.05) ------------- ------------- ------------- ------------- Basic earnings per share $0.85 $1.32 $1.78 $2.72 ============= ============= ============= ============= Diluted: Weighted-average common shares outstanding 1,085,305,558 1,098,245,490 1,087,205,706 1,096,007,767 Average common shares issuable under employee benefit plans 35,172,230 47,155,819 39,817,663 46,409,180 Average common shares issuable upon conversion of convertible notes 209,409 -- 105,855 -- Average common shares issuable upon conversion of ESOP preferred stock(1) -- -- -- 3,905,822 ------------- ------------- ------------- ------------- Total weighted-average diluted shares 1,120,687,197 1,145,401,309 1,127,129,224 1,146,322,769 ============= ============= ============= ============= Earnings: Income before cumulative effect of accounting change $930 $1,458 $2,005 $3,002 Cumulative effect of accounting change -- -- (59) -- Less: Preferred stock dividend requirements (9) (9) (18) (18) ------------- ------------- ------------- ------------- Earnings applicable to common shares $921 $1,449 $1,928 $2,984 ============= ============= ============= ============= Diluted EPS before cumulative effect of accounting change $0.82 $1.26 $1.76 $2.60 Cumulative effect of accounting change -- -- (0.05) -- ------------- ------------- ------------- ------------- Diluted earnings per share $0.82 $1.26 $1.71 $2.60 ============= ============= ============= ============= (1) All shares of ESOP preferred stock were converted to common stock on January 3, 2000.