X0306 4 2018-03-01 0 0001018963 ALLEGHENY TECHNOLOGIES INC ATI 0001594792 DeCourcy Patrick J 1000 SIX PPG PLACE PITTSBURGH PA 15222 0 1 0 0 Senior VP, Finance and CFO Common Stock, $0.10 par value per share 2018-03-01 5 F 0 E 696 26.10 D 90195.1731 D Shares withheld for payment of taxes on shares of previously-restricted stock, the restrictions on which lapsed by their terms on March 1, 2018. Represents the average of the high and low trading prices for one share of the Issuer's common stock on the New York Stock Exchange on March 1, 2018. /S/ Elliot S. Davis, Attorney-in-Fact for Patrick J. DeCourcy 2018-03-05