EXHIBIT 11 MARKWEST HYDROCARBON, INC. COMPUTATION OF EARNINGS PER COMMON SHARE (000S, EXCEPT PER SHARE DATA) FOR THE YEAR ENDED DECEMBER 31, 1999 ------------------------ Net income $ 2,823 Weighted average number of outstanding shares of common stock 8,475 Basic earnings per share $ 0.33 ============ Net income $ 2,823 Weighted average number of outstanding shares of common stock 8,475 Dilutive stock options 6 ------------ 8,481 Earnings per share assuming dilution $ 0.33 ============