Common Stock, par value $0.01 per share

Mallinckrodt plc

COLLEGE BUSINESS & TECHNOLOGY PARK, DUBLIN, L2, D15

This Amendment No. 5 (the "Amendment") amends the statement on Amendment No. 4 filed on March 17, 2025, Amendment No. 3 filed on June 26, 2024, Amendment No. 2 filed on April 8, 2024 and Amendment No. 1 filed on March 11, 2024 which amended the statement on Schedule 13D originally filed by the Reporting Persons on January 17, 2024 (as amended, the "Schedule 13D"). Capitalized terms used but not otherwise defined in the Amendment shall have the meanings ascribed to such terms in the Schedule 13D. Except as otherwise provided herein, each Item of this Schedule 13D remains unchanged. This Schedule 13D is being jointly filed by each of the following persons: (1) Hein Park Capital Management LP ("Hein Park") (2) Hein Park Capital Management GP LLC ("Hein Park GP"); and (3) Courtney W. Carson ("Carson"). The foregoing persons are hereinafter sometimes referred to as the Reporting Persons. Any disclosures herein with respect to persons other than the Reporting Persons are made on information believed to be accurate after making inquiry to the appropriate party. Hein Park serves as the investment manager of certain investment funds (collectively, the "Hein Park Funds") that hold the Shares reported herein and in its capacity as investment manager of the Hein Park Funds, Hein Park has voting and dispositive power over the Shares held by the Hein Park Funds. Hein Park GP serves as the general partner of, and in such capacity controls, Hein Park and Hein Park GP is managed and controlled by Carson. This Schedule 13D relates to the Shares held of record by the Hein Park Funds.

The address of the principal business and principal office of each of the Reporting Persons is 888 Seventh Avenue, 41st Floor, New York, NY 10019.

The principal business of Hein Park, Hein Park GP and Carson is to serve as an investment manager or adviser to various investment funds.

During the last five (5) years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Hein Park is a limited partnership organized under the laws of the State of Delaware. Hein Park GP is a limited liability company organized under the laws of the State of Delaware. Carson is a United States citizen.

(a)-(b) The information relating to the beneficial ownership of the Shares by each of the Reporting Persons set forth in Rows 7 through 13 on each of the cover pages hereto is incorporated by reference herein and is as of the date hereof. Such information is based on the number of shares of Common Stock outstanding following the consummation of the Transaction (as defined in Amendment No.4), calculated based upon information reported in the Issuer's Form 8-K filed on August 1, 2025. By virtue of the relationship among the Reporting Persons described in Item 2, each such Reporting Person may be deemed to share the power to vote or direct the vote and to share the power to dispose of or direct the disposition of the Shares as set forth in rows 7 through 13 of the cover pages of this Statement. The filing of this Statement shall not be construed as an admission that any such Reporting Person is for the purpose of Section 13(d) or 13(g) of the Exchange Act, the beneficial owner of any securities covered by this Statement.

In connection with the Transaction, the Reporting Persons holdings of Endo, Inc. shares were converted into an additional 28,654 Shares.

The partners and members of the Hein Park Funds have the right to participate in the receipt of dividends from, or proceeds from the sale of, the Shares held for the accounts of the Hein Park Funds in accordance with their ownership interests in the respective Hein Park Fund. No individual partner or member of any Hein Park Fund has the right to receive or the power to direct the receipt of the dividends from, or the proceeds of the sale of, more than five percent of such Shares.

Not applicable.