13D Filing: VIEX Capital Advisors and A10 Networks Inc. (ATEN)

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The following constitutes
Amendment No. 1 to the Schedule 13D filed by the undersigned (the “Amendment No. 1”). This Amendment No. 1 amends the
Schedule 13D as specifically set forth herein.

Item 3. Source and Amount of Funds or Other Consideration.

Item 3 is hereby amended
and restated to read as follows:

The Shares purchased
by Series One were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in
the ordinary course of business) in open market purchases, except as otherwise noted, as set forth in Schedule A, which is incorporated
by reference herein. The aggregate purchase price of the 1,763,575 Shares beneficially owned by Series One is approximately $10,356,357,
including brokerage commissions. The aggregate purchase price of the 120,000 Shares underlying certain call options which are currently
exercisable and may be deemed to be beneficially owned by Series One is approximately $5,300, including brokerage commissions.

The Shares purchased
by VSO II were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the
ordinary course of business) in open market purchases, except as otherwise noted, as set forth in Schedule A, which is incorporated
by reference herein. The aggregate purchase price of the 2,033,808 Shares beneficially owned by VSO II is approximately $11,786,483,
including brokerage commissions. The aggregate purchase price of the 180,000 Shares underlying certain call options which are currently
exercisable and may be deemed to be beneficially owned by VSO II is approximately $7,950, including brokerage commissions.

Item 4. Purpose of Transaction.
Item 4 is hereby amended to add the following:

On March 14, 2018,
the Reporting Persons and the Issuer entered into a letter agreement (the “Agreement”). Pursuant to the Agreement,
the Issuer increased the size of its Board of Directors (the “Board”) to six and appointed Tor R. Braham to the Board
to serve as a Class II director with a term expiring at the Company’s 2019 Annual Meeting of Stockholders (the “2019
Annual Meeting”). The Issuer will appoint Mr. Braham to the Audit Committee and to the Compensation Committee.

The Agreement further
provides that during the Restricted Period (as defined below) if (1) Mr. Braham ceases to serve on the Board and (2) at that time
the Reporting Persons beneficially owns Shares representing in the aggregate at least 2% of the Issuers’ then-outstanding
common stock, then the Issuer and Reporting Persons will cooperate to identify (and the Board will promptly appoint) another person
to serve as a director in place of Mr. Braham.

In addition, the Issuer
will recommend that stockholders approve, at the Issuers’ 2018 Annual Meeting of Stockholders (the “2018 Annual Meeting”),
a proposal to declassify the Board. If the proposal is approved, the Board will be declassified on a “rolling” basis
beginning with the 2018 Annual Meeting such that each director serving immediately prior to the 2018 Annual Meeting will complete
his term, in general, and each director elected or appointed at or after the 2018 Annual Meeting will serve a one-year term expiring
at the next annual meeting of stockholder. The Issuer also agreed to fix the size of the Board at five directors immediately following
the 2018 Annual Meeting and through the Restricted Period.

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