X0609 4 2026-05-05 0 0001580808 A10 Networks, Inc. ATEN 0001570462 Trivedi Dhrupad false C/O A10 NETWORKS, INC. 2300 ORCHARD PARKWAY SAN JOSE CA 95131 1 1 0 0 Chief Executive Officer 0 Common Stock 2026-05-05 4 M 0 63406 0 A 758641 D Common Stock 2026-05-05 4 M 0 65753 0 A 824394 D Common Stock 2026-05-06 4 F 0 32858 27.13 D 791536 D Performance-based Restricted Stock Units 2026-05-05 4 M 0 63406 0 D 2029-02-06 Common Stock 63406 63406 D Performance-based Restricted Stock Units 2026-05-05 4 M 0 65753 0 D 2030-02-12 Common Stock 65753 65763 D Performance-Based Restricted Stock Units were previously reported on February 10, 2025, each of which represents a contingent right to receive one share of common stock of ATEN, with vesting subject to the achievement of specified levels of the volume weighted average closing prices of a share of ATEN common stock during any one hundred (100) day trading period between February 6, 2025 and February 6, 2029. The first achievement date occurred on April 16, 2026, as certified by the compensation committee of ATEN, resulting in 63,406 units meeting the appropriate performance-based conditions. However, these shares remain subject to time-based vesting conditions and will therefore vest as to one-half (1/2) on May 5, 2026 and an additional one-fourth (1/4) on each of the first and second anniversaries of April 16, 2026, subject to continued employment. These shares are reflected on Table I. Performance-Based Restricted Stock Units that were previously reported on February 13, 2026, each of which represents a contingent right to receive one share of common stock of ATEN, with vesting subject to the achievement of specified levels of the volume weighted average closing prices of a share of ATEN common stock during any one hundred (100) day trading period between February 12, 2026 and February 12, 2030. The first achievement date occurred on April 22, 2026, as certified by the compensation committee of ATEN, resulting in 65,753 units meeting the appropriate performance-based conditions. However, these shares remain subject to time-based vesting conditions and will therefore vest as to one-half (1/2) on May 5, 2026 and an additional one-fourth (1/4) on each of the first and second anniversaries of April 22, 2026, subject to continued employment. These shares are reflected on Table I. Includes 16,130 shares and 16,728 shares automatically withheld, on a non-discretionary basis, for tax purposes related to a February 6, 2025 performance-based restricted stock unit grant and a February 12, 2026 performance-based restricted stock unit grant, respectively, each that vested on May 5, 2026. /s/ Jill Osato, Attorney-in-fact 2026-05-06