Sec Form 4 Filing - Trivedi Dhrupad @ A10 Networks, Inc. - 2025-03-10

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Trivedi Dhrupad 2. Issuer Name and Ticker or Trading Symbol A10 Networks, Inc. [ ATEN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Executive Officer (Last) (First) (Middle) C/O A10 NETWORKS, INC., 2300 ORCHARD PARKWAY 3. Date of Earliest Transaction (MM/DD/YY) 03/10/2025 (Street) SAN JOSE, CA95131 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 03/10/2025 M 48,711 ( 1 ) A $ 0 737,107 D Common Stock 03/10/2025 M 79,417 ( 2 ) A $ 0 816,524 D Common Stock 03/11/2025 F 28,409 ( 3 ) D $ 19.38 788,115 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Performance-based Restricted Stock Units ( 1 ) 03/10/2025 M 48,711 ( 1 ) 01/25/2026 Common Stock 48,711 $ 0 0 D Performance-based Restricted Stock Units ( 2 ) 03/10/2025 M 79,417 ( 2 ) 02/21/2027 Common Stock 79,417 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Trivedi Dhrupad C/O A10 NETWORKS, INC. 2300 ORCHARD PARKWAY SAN JOSE, CA95131 X Chief Executive Officer Signatures /s/ Jill Osato, Attorney-in-fact 03/11/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Performance-Based Restricted Stock Units ("PSUs") were previously reported on January 27, 2022, 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 January 25, 2022 and January 25, 2026. The third milestone achievement date occurred on February 24, 2025, as certified by the compensation committee of ATEN, resulting in 48,711 units meeting the appropriate performance-based conditions. However, these shares remain subject to time-based vesting conditions and will therefore vest as to one-third (1/3) on March 10, 2025 and an additional one-third (1/3) on each of the first and second anniversaries of February 24, 2025, subject to continued employment. These shares are reflected on Table I. ( 2 )PSUs that were previously reported on February 22, 2023, each of which represents a contingent right to receive one share of common stock of ATEN, withvesting 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 betweenFebruary 21, 2023 and February 21, 2027. The second achievement date occurred on February 28, 2025, as certified by the compensation committee of ATEN, resulting in 79,417 units meeting theappropriate performance-based conditions. However, these shares remain subject to time-based vesting conditions and will therefore vest as to one-half (1/2) on March 10, 2025 and an additional one-fourth (1/4) on each of the first and second anniversaries of February 28, 2025, subject to continued employment. These shares are reflected on Table I. ( 3 )Includes 8,245 shares automatically withheld, on a non-discretionary basis, for tax purposes related to a January 25, 2022 performance restricted stock unit grant, and 20,164 shares automatically withheld, on a non-discretionary basis, for tax purposes related to a February 21, 2023 performance restricted stock unit grant, each that vested on March 10, 2025.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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