Basic earnings per share (EPS) amounts are computed by dividing Net income (loss) attributable to Alcoa Corporation by the average number of common shares outstanding. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive share equivalents outstanding.

The share information used to compute basic and diluted EPS attributable to Alcoa Corporation common shareholders was as follows (shares in millions):

	2021		2020		2019
Average shares outstanding—basic		186		186		185
Effect of dilutive securities:
Stock options		—		—		—
Stock units		4		—		—
Average shares outstanding—diluted		190		186		185

Options to purchase less than two hundred thousand shares of common stock outstanding as of December 31, 2021 at a weighted average exercise price of $38.67 per share were not included in the computation of diluted EPS because the exercise prices of these options were greater than the annual average market price of Alcoa Corporation’s common stock.

In 2020, basic average shares outstanding and diluted average shares outstanding were the same because the effect of potential shares of common stock was anti-dilutive. Had Alcoa generated net income in 2020, one million common share equivalents related to five million outstanding stock units and stock options combined would have been included in diluted average shares outstanding for the respective period. Options to purchase two million shares of common stock outstanding at December 31, 2020 had a weighted average exercise price of $26.85 per share which was greater than the annual average market price per share of Alcoa Corporation’s common stock.

In 2019, basic average shares outstanding and diluted average shares outstanding were the same because the effect of potential shares of common stock was anti-dilutive. Had Alcoa generated net income in 2019, one million common share equivalents related to four million outstanding stock units and stock options combined would have been included in diluted average shares outstanding for the respective period. Options to purchase two million shares of common stock outstanding at December 31, 2019 had a weighted average exercise price of $32.66 per share which was greater than the annual average market price per share of Alcoa Corporation’s common stock.