4. Earnings Per Share

Basic earnings per share is calculated by dividing the net income by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is calculated by dividing the earnings by the weighted-average number of common shares and potentially dilutive securities outstanding during the period. Potentially dilutive common shares consist of restricted stock units, incremental common shares issuable upon exercise of stock options and shares issuable under the employee stock purchase plan. The dilutive effect of outstanding shares is reflected in diluted earnings per share using the treasury stock method, as applicable. This method includes consideration of the amounts to be paid by the employees and the amount of unrecognized stock-based compensation related to future services. No potential dilutive common shares are included in the computation of any diluted per share amount when a net loss is reported.