ADVANCED DRAINAGE SYSTEMS, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-K

For the fiscal year ended March 31, 2026

OR

For the transition period from to

COMMISSION FILE NO.:001-36557

ADVANCED DRAINAGE SYSTEMS, INC.

(Exact name of registrant as specified in its charter)

4024 Green Stripe Lane, Hilliard, Ohio 43026

(Address of principal executive offices and zip code)

(800)733-7473

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act: Common Stock, $0.01 par value per share

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☒ No☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes☐ No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No☐

Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes ☒ No☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one)

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. Yes☒ No☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b)☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐ No☒

The aggregate market value of the shares of common stock held by non-affiliates of the registrant (treating all executive officers and directors of the registrant, for this purpose, as affiliates of the registrant) was $10,679 million as of September 30, 2025, the last business day of the registrant’s most recently completed second fiscal quarter, based on the reported closing price of the shares of common stock as reported on the New York Stock Exchange on September 30, 2025.

As of May 14, 2026, the registrant had 76,595,708 shares of common stock outstanding. The shares of common stock trade on the New York Stock Exchange under the ticker symbol “WMS.” In addition, as of May 14, 2026, 221,893 shares of unvested restricted common stock were outstanding and a total of 76,817,601 shares of common stock were outstanding, inclusive of outstanding shares of unvested restricted common stock.

DOCUMENTS INCORPORATED BY REFERENCE

Part III of this report incorporates by reference specific portions of the Registrant’s Notice of Annual Meeting and Proxy Statement relating to the Annual Meeting of Stockholders to be held on July 16, 2026, which statement will be filed no later than 120 days after the end of the fiscal year covered by this report.

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