COMMONWEALTH EDISON CO

Item 1.01. Entry into a Material Definitive Agreement. On May 14, 2026, Commonwealth Edison Company (ComEd) issued $600 million aggregate principal amount of its First Mortgage 4.550% Bonds, Series 139, due June 1, 2031 (Series 139 Bonds), and $825 million aggregate principal amount of its First Mortgage 5.850% Bonds, Series 140, due June 1, 2056 (Series 140 Bonds and, together with the Series 139 Bonds, the Bonds). See Item 2.03 below for a description of the Bonds and related agreements.

Item 2.03. Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. On May 14, 2026, ComEd issued $600 million aggregate principal amount of its First Mortgage 4.550% Bonds, Series 139, due June 1, 2031, and $825 million aggregate principal amount of its First Mortgage 5.850% Bonds, Series 140, due June 1, 2056. The Bonds were issued pursuant to ComEd’s Mortgage dated July 1, 1923, as amended and supplemented by supplemental indentures, including the Supplemental Indenture dated August 1, 1944 (Mortgage) and the Supplemental Indenture dated as of May 1, 2026 (Supplemental Indenture). The Mortgage is a first mortgage on ComEd’s utility plant. The proceeds of the Bonds will be used by ComEd (i) to redeem $500 million of its First Mortgage 2.550% Bonds, Series 120 due June 15, 2026 and (ii) for general corporate purposes. The Bonds were registered under the Securities Act of 1933, as amended, pursuant to ComEd’s Registration Statement on Form S-3 (Registration No. 333-284911-01), as amended, filed with the Securities and Exchange Commission (SEC), which registration statement was declared effective by the SEC on April 8, 2025. The Series 139 Bonds carry an interest rate of 4.550% per annum, and the Series 140 Bonds carry an interest rate of 5.850% per annum. Interest on the Bonds is payable semi-annually on June 1 and December 1, commencing December 1, 2026. The Bonds are redeemable in whole or in part at ComEd’s option at any time prior to May 1, 2031 (one month prior to the maturity date of the Series 139 bonds) (Series 139 Par Call Date), in the case of the Series 139 Bonds, or prior to December 1, 2055 (six months prior to the maturity date of the Series 140 bonds) (Series 140 Par Call Date), in the case of the Series 140 Bonds, at a redemption price equal to the greater of 100% of the principal amount to be redeemed or a “make-whole” redemption price calculated as provided in the Supplemental Indenture, plus accrued and unpaid interest to the redemption date. On or after the Series 139 Par Call Date, in the case of the Series 139 Bonds, or on or after the Series 140 Par Call Date, in the case of the Series 140 Bonds, we may redeem the Bonds, in whole or in part, at any time and from time to time, at a redemption price equal to 100% of the principal amount of the Bonds being redeemed plus accrued and unpaid interest thereon to the redemption date. A copy of the Supplemental Indenture, which sets forth the terms of the Bonds, is attached hereto as Exhibit 4.1 and is incorporated herein by reference. In connection with the issuance of the Bonds, Ballard Spahr LLP provided ComEd with the legal opinion attached to this Current Report as Exhibit 5.1. A copy of the Underwriting Agreement dated May 7, 2026 among ComEd and BofA Securities, Inc., Citigroup Global Markets Inc., Loop Capital Markets LLC, RBC Capital Markets, LLC and U.S. Bancorp Investments, Inc., as representatives of the several underwriters named therein, is filed as Exhibit 1.1 to this Current Report. Some of the underwriters and their affiliates have engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with ComEd and its affiliates. They have received customary fees and commissions for these transactions. In addition, some of the underwriters or some of the banking affiliates of the underwriters are lending parties in ComEd’s revolving credit facility.