SIMPSON MANUFACTURING CO., INC. AND SUBSIDIARIES Computation of Earnings Per Common Share For the Three Years Ended December 31, 1998, 1997 and 1996 Exhibit 11 Basic Earnings per Share 1998 1997 1996 ------------ ------------ ------------ Weighted average number of common shares outstanding 11,556,629 11,471,217 11,422,995 Shares issuable pursuant to stock bonus plan 3,825 3,375 1,950 ------------ ------------ ------------ Number of shares for computation of basic net income per share 11,560,454 11,474,592 11,424,945 ============ ============ ============ Net income for computation of basic net income per share $ 31,141,523 $ 25,985,779 $ 19,720,638 ============ ============ ============ Basic net income per share $ 2.69 $ 2.26 $ 1.73 ============ ============ ============ SIMPSON MANUFACTURING CO., INC. AND SUBSIDIARIES Computation of Earnings Per Common Share For the Three Years Ended December 31, 1998, 1997 and 1996 Exhibit 11 (continued) Diluted Earnings per Share 1998 1997 1996 ------------ ------------ ------------ Weighted average number of common shares outstanding 11,556,629 11,471,217 11,422,995 Shares issuable pursuant to employee stock option plans, less shares assumed repurchased at the average fair value during the period 483,361 486,337 326,604 Shares issuable pursuant to the independent director stock option plan, less shares assumed repurchased at the average fair value during the period 4,382 5,021 3,635 Shares issuable pursuant to stock bonus plan 3,825 3,375 1,950 ------------ ------------ ------------ Number of shares for computation of diluted net income per share 12,048,197 11,965,950 11,755,184 ============ ============ ============ Net income for computation of diluted net income per share $ 31,141,523 $ 25,985,779 $ 19,720,638 ============ ============ ============ Diluted net income per share $ 2.58 $ 2.17 $ 1.68 ============ ============ ============