Sec Form 4 Filing - Akastor ASA @ HMH Holding Inc - 2026-04-02

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 Akastor ASA 2. Issuer Name and Ticker or Trading Symbol HMH Holding Inc [ HMH] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) OKSENOYVEIEN 10 3. Date of Earliest Transaction (MM/DD/YY) 04/02/2026 (Street) LYSAKER, TX1366 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 Class B common stock 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 8,144,374 A $ 0 8,144,374 I Mercury HoldCo Inc. See footnotes ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) Class B common stock 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 8,144,374 A $ 0 16,288,748 I Akastor AS See footnotes ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 )

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 B.V. Voting Class A Shares ( 1 ) ( 2 ) ( 3 ) ( 5 ) 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 1,050,000 ( 1 )( 2 )( 3 )( 5 ) ( 1 )( 2 )( 3 )( 5 ) Class A common stock 1,050,000 $ 9.4 16,288,748 I Mercury HoldCo Inc. ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) B.V. Voting Class B Shares ( 1 ) ( 2 ) ( 3 ) ( 5 ) 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 1,050,000 ( 1 )( 2 )( 3 )( 5 ) ( 1 )( 2 )( 3 )( 5 ) Class A common stock 1,050,000 $ 9.4 16,288,748 I Akastor AS ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) B.V. Voting Class A Shares ( 1 ) ( 2 ) ( 3 ) ( 5 ) 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 16,288,748 ( 1 )( 2 )( 3 )( 5 ) ( 1 )( 2 )( 3 )( 5 ) Class A common stock 16,288,748 $ 0 0 I Mercury HoldCo Inc. ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) B.V. Voting Class B Shares ( 1 ) ( 2 ) ( 3 ) ( 5 ) 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 16,288,748 ( 1 )( 2 )( 3 )( 5 ) ( 1 )( 2 )( 3 )( 5 ) Class A common stock 16,288,748 $ 0 0 I Akastor AS ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) B.V. Non-Voting Class A Shares ( 1 ) ( 2 ) ( 3 ) ( 5 ) 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 16,288,748 09/27/2026( 1 )( 2 )( 3 )( 5 ) ( 1 )( 2 )( 3 )( 5 ) Class A common stock 16,288,748 $ 0 16,288,748 I Mercury HoldCo Inc. ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 ) B.V. Non-Voting Class B Shares ( 1 ) ( 2 ) ( 3 ) ( 5 ) 04/02/2026 J( 1 )( 2 )( 3 )( 5 ) 16,288,748 09/27/2026( 1 )( 2 )( 3 )( 5 ) ( 1 )( 2 )( 3 )( 5 ) Class A common stock 16,288,748 $ 0 16,288,748 I Akastor AS ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 5 ) ( 6 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Akastor ASA OKSENOYVEIEN 10 LYSAKER1366 X Akastor AS OKSENOYVEIEN 10 LYSAKER1366 X X Director by Deputization Mercury HoldCo AS OKSENOYVEIEN 10 LYSAKER1366 X Mercury HoldCo Inc. 3300 NORTH SAM HOUSTON PARKWAY EAST HOUSTON, TX77032 X X Director by Deputization Signatures /s/ Karl Erik Kjelstad, as Chief Executive Officer of Akastor ASA 04/02/2026 Signature of Reporting Person Date /s/ Oyvind Paaske, Chair of Akastor AS 04/02/2026 Signature of Reporting Person Date /s/ Oyvind Paaske, Chair of Mercury HoldCo AS 04/02/2026 Signature of Reporting Person Date /s/ Askel Matre, Director of Mercury HoldCo Inc. 04/02/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2) ( 2 )(cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3) ( 3 )(cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively. ( 4 )Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities. ( 5 )Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire. ( 6 )Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

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