Sec Form 4 Filing - LAVIN RICHARD P @ Allison Transmission Holdings Inc - 2025-05-07

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 LAVIN RICHARD P 2. Issuer Name and Ticker or Trading Symbol Allison Transmission Holdings Inc [ ALSN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ALLISON TRANSMISSION HOLDINGS, INC., ONE ALLISON WAY 3. Date of Earliest Transaction (MM/DD/YY) 05/07/2025 (Street) INDIANAPOLIS, IN46222 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 Common Stock ( 1 ) 05/07/2025 M 31,584 ( 1 ) ( 2 ) A $ 0 41,410 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 Deferred Stock Units ( 3 ) 05/07/2025 M 2,859 ( 4 ) ( 4 ) Common Stock 2,859 $ 0 0 D Dividend Equivalents Rights ( 5 ) 05/07/2025 M 1,888 ( 6 ) ( 6 ) Common Stock 1,888 $ 0 25 D Deferred Stock Units ( 3 ) 05/07/2025 M 477 ( 7 ) ( 7 ) Common Stock 477 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 473 ( 8 ) ( 8 ) Common Stock 473 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 464 ( 9 ) ( 9 ) Common Stock 464 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 482 ( 10 ) ( 10 ) Common Stock 482 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 2,880 ( 11 ) ( 11 ) Common Stock 2,880 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 245 ( 12 ) ( 12 ) Common Stock 245 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 227 ( 13 ) ( 13 ) Common Stock 227 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 246 ( 14 ) ( 14 ) Common Stock 246 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 298 ( 15 ) ( 15 ) Common Stock 298 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 3,600 ( 16 ) ( 16 ) Common Stock 3,600 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 283 ( 17 ) ( 17 ) Common Stock 283 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 280 ( 18 ) ( 18 ) Common Stock 280 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 242 ( 19 ) ( 19 ) Common Stock 242 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 249 ( 20 ) ( 20 ) Common Stock 249 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 2,927 ( 21 ) ( 21 ) Common Stock 2,927 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 633 ( 22 ) ( 22 ) Common Stock 633 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 689 ( 23 ) ( 23 ) Common Stock 689 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 631 ( 24 ) ( 24 ) Common Stock 631 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 614 ( 25 ) ( 25 ) Common Stock 614 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 3,746 ( 26 ) ( 26 ) Common Stock 3,746 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 656 ( 27 ) ( 27 ) Common Stock 656 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 577 ( 28 ) ( 28 ) Common Stock 577 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 538 ( 29 ) ( 29 ) Common Stock 538 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 547 ( 30 ) ( 30 ) Common Stock 547 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 3,146 ( 31 ) ( 31 ) Common Stock 3,146 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 547 ( 32 ) ( 32 ) Common Stock 547 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 614 ( 33 ) ( 33 ) Common Stock 614 $ 0 0 D Deferred Stock Units ( 3 ) 05/07/2025 M 526 ( 34 ) ( 34 ) Common Stock 526 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other LAVIN RICHARD P C/O ALLISON TRANSMISSION HOLDINGS, INC. ONE ALLISON WAY INDIANAPOLIS, IN46222 X Signatures /s/ Preston B. Ray, Attorney-in-Fact 05/09/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents the deferred stock units ("DSUs") and dividend equivalents payable upon the reporting person's separation from service. The reporting person did not stand for re-election at Allison Transmission Holdings, Inc.'s (the "Company") 2025 annual meeting of stockholders and his term ended on May 7, 2025. ( 2 )Includes 29,696 DSUs and 1,888 related dividend equivalents. ( 3 )Each DSU is the economic equivalent of one share of the Company's common stock. The DSUs become payable, in common stock, or at the Company's election cash, at the earlier of the reporting person's separation from service or change in control. DSUs earn dividend equivalents when dividends are declared on the Company's common stock. ( 4 )On May 10, 2018, the reporting person was granted 2,859 DSUs that vested on May 8, 2019. ( 5 )Each dividend equivalent right is the economic equivalent of one share of the Company's common stock. ( 6 )The dividend equivalent rights accrued on previously awarded DSUs and were payable on May 7, 2025, the date of the reporting person's separation from service. ( 7 )On August 10, 2018, the reporting person was granted 477 DSUs that vested on August 10, 2018. ( 8 )On November 12, 2018 the reporting person was granted 473 DSUs that vested on November 12, 2018. ( 9 )On February 11, 2019, the reporting person was granted 464 DSUs that vested on February 11, 2019. ( 10 )On May 8, 2019 the reporting person was granted 482 DSUs that vested on May 8, 2019. ( 11 )On May 9, 2019, the reporting person was granted 2,880 DSUs that vested on May 6, 2020. ( 12 )On August 9, 2019, the reporting person was granted 245 DSUs that vested on August 9, 2019. ( 13 )On November 8, 2019, the reporting person was granted 227 DSUs that vested on November 8, 2019. ( 14 )On February 10, 2020, the reporting person was granted 246 DSUs that vested on February 10, 2020. ( 15 )On May 6, 2020, the reporting person was granted 298 DSUs that vested on May 6, 2020. ( 16 )On May 7, 2020, the reporting person was granted 3,600 DSUs that vested on May 5, 2021. ( 17 )On August 7, 2020, the reporting person was granted 283 DSUs that vested on August 7, 2020. ( 18 )On November 6, 2020, the reporting person was granted 280 DSUs that vested on November 6, 2020. ( 19 )On February 8, 2021, the reporting person was granted 242 DSUs that vested on February 8, 2021. ( 20 )On May 5, 2021, the reporting person was granted 249 DSUs that vested on May 5, 2021. ( 21 )On May 6, 2021, the reporting person was granted 2,927 DSUs that vested on May 4, 2022. ( 22 )On August 6, 2021, the reporting person was granted 633 DSUs that vested on August 6, 2021. ( 23 )On November 5, 2021, the reporting person was granted 689 DSUs that vested on November 5, 2021. ( 24 )On February 4, 2022, the reporting person was granted 631 DSUs that vested on February 4, 2022. ( 25 )On May 4, 2022, the reporting person was granted 614 DSUs that vested on May 4, 2022. ( 26 )On May 5, 2022, the reporting person was granted 3,746 DSUs that vested on May 3, 2023. ( 27 )On August 5, 2022, the reporting person was granted 656 DSUs that vested on August 5, 2022. ( 28 )On November 4, 2022, the reporting person was granted 577 DSUs that vested on November 4, 2022. ( 29 )On February 3, 2023, the reporting person was granted 538 DSUs that vested on February 3, 2023. ( 30 )On May 3, 2023, the reporting person was granted 547 DSUs that vested on May 3, 2023. ( 31 )On May 4, 2023, the reporting person was granted 3,146 DSUs that vested on May 8, 2024. ( 32 )On August 3, 2023, the reporting person was granted 547 DSUs that vested on August 3, 2023. ( 33 )On November 3, 2023, the reporting person was granted 614 DSUs that vested on November 3, 2023. ( 34 )On February 5, 2024, the reporting person was granted 526 DSUs that vested on February 5, 2024.

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

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