X0306 4 2021-06-30 0001109357 EXELON CORP EXC 0001087426 SHATTUCK MAYO A III 10 SOUTH DEARBORN STREET 54TH FLOOR CHICAGO IL 60603 1 0 0 1 Chairman of the Board Common Stock (Deferred Stock Units) 2021-06-30 4 A 0 830 46.71 A 32933 I By Exelon Directors Deferred Stock Unit Plan Common Stock 267649 D Common Stock 10000 I By Lizzie Mae, LLC Common Stock (401k shares) 2329 I By 401(k) plan Balance includes 261 shares acquired on June 10, 2021 through automatic dividend reinvestment. The reporting person is a manager of Lizzie Mae, LLC, whose members are trusts for the benefit of the reporting person's children. The reporting person disclaims beneficial ownership of the Exelon Corporation common stock held by Lizzie Mae, LLC except to the extent of his pecuniary interest therein. Shares held as of June 30, 2021 in a multi-fund 401(K) plan updated to reflect additional shares in the account acquired through automatic dividend reinvestment. Elizabeth M. Hensen, Attorney in Fact for Mayo A. Shattuck III 2021-07-01