X0306 4 2017-12-13 0 0001580808 A10 Networks, Inc. ATEN 0001206124 CHEN LEE C/O A10 NETWORKS, INC. 3 WEST PLUMERIA DRIVE SAN JOSE CA 95134 1 1 1 0 CEO and President Common Stock 2017-12-13 4 S 0 25000 7.76 D 10061538 D Common Stock 3200 I See footnote The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person. This is the weighted average sale price of the shares, which ranged from $7.70 to $7.81 per share. Upon request by the Commission staff, the Issuer, or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price within the range set forth in this Form 4. Shares held of record by the U/A DTD 07/25/2000 Lee Chen Family Trust, for which the Reporting Person serves as a trustee. /s/ Robert D. Cochran, as Attorney-in-Fact 2017-12-14