HII · Huntington Ingalls Industries, Inc.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 12, 2026.

Represents the weighted average sale price of $324.92 rounded to the nearest hundredth. The highest price at which the shares were sold was $325.11 and the lowest price at which the shares were sold was $324.83. 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.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock issued in lieu of cash pursuant to the Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan ("Plan") in an exempt transaction pursuant to Rule 16b-3.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP") and vest ratably in three equal installments upon each of the first, second and third anniversaries of the grant date.

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock deferred into stock unit account pursuant to Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan in an exempt transaction pursuant to Rule 16b-3.

Shares of common stock issued in lieu of cash pursuant to the Huntington Ingalls Industries, Inc. 2022 Long-Term Incentive Stock Plan ("Plan") in an exempt transaction pursuant to Rule 16b-3.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Pursuant to the Huntington Ingalls Industries, Inc. 2012 and 2022 Long-Term Incentive Stock Plan (together, the "LTISPs"), dividend equivalents are credited on each director stock unit ("SUA") held by the Reporting Person following the payment of the Company's quarterly cash dividend. Each SUA represents a right to receive one share of Company common stock, which will generally become payable within 30 days following the date a non-employee director ceases to provide services as a member of the board of directors. The number of dividend equivalents acquired by the Reporting Person under the LTISPs is calculated by dividing the aggregate amount of the dividend paid on the total number of SUAs held by the Reporting Person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP").

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.

Each Restricted Stock Right ("RSR") represents a contingent right to receive an equivalent number of shares of Company common stock, or, at the discretion of the Company's Compensation Committee, cash or a combination of cash and Company common stock. The RSRs were granted under the 2022 Long-Term Incentive Stock Plan ("LTISP").

The amount acquired represents dividend equivalent rights on the RSRs, which are credited following payment of the Company's quarterly cash dividend. Pursuant to the LTISP, the number of dividend equivalent rights acquired is calculated by dividing the aggregate amount of the dividend paid on the total number of RSRs held by the reporting person by the closing price of a share of Company common stock on the dividend payment date.