1 EXHIBIT 11-8 DTE ENERGY COMPANY BASIC AND DILUTED EARNINGS PER SHARE OF COMMON STOCK Year Ended December 31 ----------------------------------------------- 1999 1998 1997 ---- ---- ---- (Thousands, except per share amounts) BASIC: Net Income................................................. $ 482,653 $ 443,012 $ 417,333 Weighted average number of common shares outstanding (a)................................... 145,047 145,076 145,101 Earnings per share of Common Stock based on weighted average number of shares outstanding.................................... $ 3.33 $ 3.05 $ 2.88 DILUTED: Net Income................................................. $ 482,653 $ 443,012 $ 417,333 Weighted average number of common shares outstanding (a)................................... 145,047 145,076 145,101 Incremental shares from assumed conversion of options.................................... 89 106 12 ------------- ------------- ------------- 145,136 145,182 145,113 ============= ============= ============= Earnings per share of Common Stock assuming conversion of options........................... $3.33 $ 3.05 $ 2.88 - ----------------------------------- (a) Based on a daily average.