Sec Form 4 Filing - Boudreaux Chad N. @ HUNTINGTON INGALLS INDUSTRIES, INC. - 2025-06-03

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 Boudreaux Chad N. 2. Issuer Name and Ticker or Trading Symbol HUNTINGTON INGALLS INDUSTRIES, INC. [ HII] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Ex VP & Chief Legal Officer (Last) (First) (Middle) 4101 WASHINGTON AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 06/03/2025 (Street) NEWPORT NEWS, VA23607 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 06/03/2025 S 1,965 D $ 228.9432 ( 1 ) 21,228.212 D Common Stock 06/03/2025 I 1,241.8 ( 2 ) D $ 227.96 0 I By 401(k) plan

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 SEP < /td> ( 3 ) 06/03/2025 I 4,015.98 ( 3 ) ( 3 ) ( 3 ) Common Stock 932.4125 $ 227.96 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Boudreaux Chad N. 4101 WASHINGTON AVENUE NEWPORT NEWS, VA23607 Ex VP & Chief Legal Officer Signatures /s/ Tiffany M. King, Attorney-in-Fact 06/05/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents the weighted average sale price of $228.9432 rounded to the nearest hundredth. The highest price at which the shares were sold was $228.950 and the lowest price at which the shares were sold was $228.869. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote in this Form 4. ( 2 )The transaction constitutes an intra-plan transfer in the Huntington Ingalls Industries, Inc. Saving Plan (the "Plan") from the HII Stock Fund to another investment option. The reporting person's interest in the HII Stock Fund was held in the form of units of interest. The Plan's administrator calculates the number of shares of issuer common stock represented by units in the HII Stock Fund. ( 3 )The transaction constitutes an intra-plan transfer in the Huntington Ingalls Industries, Inc. Saving Excess Plan (the "SEP") from the HII Stock Fund to another investment option. The reporting person's interest in the HII Stock Fund is held in the form of units of interest. The SEP 's administrator calculates the number of shares of issuer common stock represented by units in the HII Stock Fund.

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

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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