EXHIBIT 11 Morgan Stanley Dean Witter & Co. Computation of Earnings Per Share (In millions, except share data) Three Months Ended Nine Months Ended ----------------------------- --------------------------- August 31, August 31, August 31, August 31, 1998 1997 1998 1997 ------------- ----------- ----------- ----------- Basic: Weighted-average shares outstanding 573,170,507 578,082,806 582,105,755 574,048,186 =========== =========== =========== =========== Earnings: Net income $645 $678 $2,190 $1,776 Less: Preferred stock dividend requirements 14 15 43 52 ------------ ----------- ----------- ----------- Earnings applicable to common shares $631 $663 $2,147 $1,724 ============ ============ ============ =========== Basic earnings per share $1.10 $1.15 $3.69 $3.00 ============ ============ ============ =========== Diluted: Weighted-average shares outstanding 573,170,507 578,082,806 582,105,755 574,048,186 Average common shares issuable under employee benefit plans 19,708,913 19,839,048 19,201,179 19,370,268 Average common shares issuable upon conversion of ESOP preferred stock 11,900,174 12,097,268 11,958,273 12,146,732 ------------ ----------- ----------- ----------- Total weighted-average diluted shares 604,779,594 610,019,122 613,265,207 605,565,186 ============ ============ ============ =========== Earnings: Net income $645 $678 $2,190 $1,776 Less: Preferred stock dividend requirements 13 14 38 49 ------------ ----------- ----------- ----------- Earnings applicable to common shares $632 $664 $2,152 $1,727 ============ ============ ============ =========== Diluted earnings per share $1.05 $1.09 $3.51 $2.85 ============ ============ ============ ===========