NPK International Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2025

or

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from __________ to __________

Commission File Number:001-02960

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code:(281)362-6800

Securities registered pursuant to Section 12(b) of the Act:

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 company, 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.

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.

☑

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.

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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 Act).

Yes☐ No☑

The aggregate market value of the voting and non-voting common equity held by non-affiliates of the registrant, computed by reference to the price at which the common equity was last sold as of June 30, 2025, was $683.7 million. The aggregate market value has been computed by reference to the closing sales price on such date, as reported by The New York Stock Exchange.

As of February 20, 2026, a total of 84,527,934 shares of common stock, $0.01 par value per share, were outstanding.

Documents Incorporated by Reference:

Pursuant to General Instruction G(3) to this Form 10-K, the information required by Items 10, 11, 12, 13 and 14 of Part III hereof is incorporated by reference from the registrant’s definitive Proxy Statement for its 2026 Annual Meeting of Stockholders.

INDEX TO ANNUAL REPORT ON FORM 10-K

FOR THE YEAR ENDED DECEMBER 31, 2025

CAUTIONARY STATEMENT CONCERNING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995, as amended. We also may provide oral or written forward-looking statements in other materials we release to the public. Words such as “will,” “may,” “could,” “would,” “should,” “anticipates,” “believes,” “estimates,” “expects,” “plans,” “intends,” and similar expressions are intended to identify these forward-looking statements but are not the exclusive means of identifying them. These forward-looking statements reflect the current views of our management as of the filing date of this Annual Report on Form 10-K; however, various risks, uncertainties, contingencies, and other factors, some of which are beyond our control, are difficult to predict and could cause our actual results, performance, or achievements to differ materially from those expressed in, or implied by, these statements.

We assume no obligation to update, amend, or clarify publicly any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by securities laws. In light of these risks, uncertainties, and assumptions, the forward-looking events discussed in this Annual Report on Form 10-K might not occur.

For additional information regarding these and other factors, risks, and uncertainties that could cause actual results to differ, we refer you to the risk factors set forth in Item 1A “Risk Factors” in this Annual Report on Form 10-K.