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Basic earnings (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the period. Diluted earnings (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the period and the number of additional shares of common stock that would have been outstanding if potentially dilutive securities had been issued. Potentially dilutive securities include stock options and shares issuable under our Purchase Plan. The dilutive effect of

these potentially dilutive securities is reflected in diluted earnings per share by application of the treasury stock method. Under the treasury stock method, an increase in the fair market value of our common stock can result in a greater dilutive effect from potentially dilutive securities.

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The following table sets forth the computation of basic and diluted earnings per share for the three and six months ended June 30, 2020 and 2019 (in thousands except per share amounts):

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We had securities which could potentially dilute basic earnings per share, but were excluded from the computation of diluted earnings (loss) per share for all periods presented, as their effect would have been antidilutive. These securities consist of the following (in thousands):

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