A10 Networks Files Prospectus Supplement; Legal Opinion Attached

What Happened

• A10 Networks, Inc. announced that on August 6, 2026 it filed a prospectus supplement to its automatic shelf registration statement on Form S-3 (Reg. No. 333-298099) with the SEC.
• This Form 8-K (filed August 7, 2026) was submitted solely to attach the opinion of Pillsbury Winthrop Shaw Pittman LLP regarding the legality of the issuance and sale of the securities described in that prospectus supplement; that opinion is included as Exhibit 5.1.

Key Details

• Date of prospectus supplement filing: August 6, 2026.
• Shelf registration referenced: Form S-3, Registration No. 333-298099.
• Legal counsel providing opinion: Pillsbury Winthrop Shaw Pittman LLP (Exhibit 5.1); consent of counsel is included.
• The 8-K contains no terms, amounts, or other deal specifics for any securities offering.

Why It Matters

• The filing indicates A10 has taken a formal step to enable the potential issuance and sale of securities under its existing S-3 shelf, which gives the company flexibility to raise capital if it chooses.
• The attached legal opinion is a standard requirement for securities offerings and confirms counsel's view on the legality of the proposed issuance; the filing itself does not disclose any offering size, pricing, timing, or financial impact.