1 EXHIBIT 11-17 DTE ENERGY COMPANY BASIC AND DILUTED EARNINGS PER SHARE OF COMMON STOCK Three Months Nine Months Ended Ended September 30, 1999 September 30, 1999 ------------------ ------------------ (Thousands, except per share amounts) BASIC: Net income........................................................$ 160,560 $ 386,124 Weighted average number of common shares outstanding (a).......................................... 145,045 145,049 Earnings per share of common stock based on weighted average number of shares outstanding...........................................$ 1.11 $ 2.66 DILUTED: Net income........................................................$ 160,560 $ 386,124 Weighted average number of common shares outstanding (a).......................................... 145,045 145,049 Incremental shares from assumed exercise of options...................................................... 86 107 ------------ ----------- 145,131 145,156 ============ =========== Earnings per share of common stock assuming exercise of options....................................$ 1.11 $ 2.66 - ------------------------------------------------------------------- (a) Based on a daily average.