X0306 4 2021-03-01 0 0001501585 HUNTINGTON INGALLS INDUSTRIES, INC. HII 0001706050 Boykin Jennifer R. C/O HUNTINGTON INGALLS INDUSTRIES, INC. 4101 WASHINGTON AVE. NEWPORT NEWS VA 23607 0 1 0 0 Ex VP, President NNS Common Stock 2021-03-01 4 A 0 4171 178.41 A 9799.932 D Common Stock 2021-03-02 4 F 0 1909 178.41 D 7890.932 D Common Stock 3579.01 I By 401(k) plan SEP Unit Common Stock 1418.27 6023.3877 D The Huntington Ingalls Industries, Inc. Compensation Committee determined that all performance goals had been met for these restricted stock units, and they were issued on March 1, 2021. The transaction constitutes an intra-plan transfer in the Huntington Ingalls Industries, Inc. Savings Excess Plan (the "Plan") from one investment option to the HII Stock Fund. The reporting person's interest in the HII Stock Fund is 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. /s/ Kathy S. Owen, Attorney-in-Fact for Jennifer R. Boykin 2021-03-02