Sec Form 4 Filing - Casey Mark J @ Mallinckrodt plc - 2022-06-16

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 Casey Mark J 2. Issuer Name and Ticker or Trading Symbol Mallinckrodt plc [ MNKPF] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) EVP & Chief Legal Officer (Last) (First) (Middle) 675 MCDONNELL BLVD. 3. Date of Earliest Transaction (MM/DD/YY) 06/16/2022 (Street) HAZELWOOD, MO63042 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 Ordinary Shares 06/16/2022 D( 1 )( 2 )( 3 ) 32,011 D $ 0 0 D

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 Employee Share Options (Right to Buy) $ 18.15 06/16/2022 D( 1 )( 2 )( 3 ) 39,581 02/01/2019 02/01/2028 Ordinary Shares 39,581 $ 0 0 D Employee Share Options (Right to Buy) $ 13.8 06/16/2022 D( 1 )( 2 )( 3 ) 128,657 04/02/2019 04/02/2028 Ordinary Shares 128,657 $ 0 0 D Employee Share Options (Right to Buy) $ 22.26 06/16/2022 D( 1 )( 2 )( 3 ) 78,129 04/01/2020 04/01/2029 Ordinary Shares 78,129 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Casey Mark J 675 MCDONNELL BLVD. HAZELWOOD, MO63042 EVP & Chief Legal Officer Signatures /s/ Mark J. Casey 06/21/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On October 12, 2020, Mallinckrodt plc, an Irish public limited company in examination under Part 10 of the Companies Act 2014 of Ireland ("Mallinckrodt"), and certain of its subsidiaries voluntarily initiated proceedings under chapter 11 of title 11 of the United States Code (the "Bankruptcy Code") in the U.S. Bankruptcy Court for the District of Delaware (the "Bankruptcy Court"). On February 3, 2022, the Bankruptcy Court issued an opinion (which was subsequently revised on February 8, 2022 to make minor corrections) stating its intention to confirm Mallinckrodt's Fourth Amended Joint Plan of Reorganization of Mallinckrodt Plc and Its Debtor Affiliates Under Chapter 11 of the Bankruptcy Code. ( 2 )(Continued from Footnote 1) On March 2, 2022, the Bankruptcy Court entered an order confirming the Fourth Amended Joint Plan of Reorganization (with Technical Modifications) of Mallinckrodt Plc and Its Debtor Affiliates Under Chapter 11 of the Bankruptcy Code (as amended, supplemented or otherwise modified, the "Plan"), and on June 16, 2022 (the "Effective Date"), the Plan became effective and Mallinckrodt emerged from bankruptcy. ( 3 )On the Effective Date, all of Mallinckrodt's previously outstanding ordinary shares (the "Ordinary Shares"), including options, warrants, rights, restricted stock units or other securities or agreements to acquire such ordinary shares, were cancelled and extinguished pursuant to the Plan.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

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