ARRAY DIGITAL INFRASTRUCTURE, INC.

On August 1, 2025, Array filed with the Secretary of State of the State of Delaware a Certificate of Amendment No. 1 to the Restated Certificate of Incorporation of United States Cellular Corporation (the “Charter Amendment”) to change the name of Array from “United States Cellular Corporation” to “Array Digital Infrastructure, Inc.”, which became effective upon filing (the “Name Change”). In connection with the Name Change, Array’s Common Stock, par value $1.00 per share (“Common Stock”), is expected to begin trading under the new ticker symbol “AD” on August 12, 2025 (the “Symbol Change”).

The Name Change and the Symbol Change do not affect the rights of Array’s security holders. Array’s Common Stock will continue to be quoted on the New York Stock Exchange. Following the Name Change, stock certificates which reflect the former name of Array will continue to be valid.

Pursuant to Section 242 of the Delaware General Corporation Law, approval of the holders of Array’s Common Stock was not required to complete the Name Change or to approve or effect the Charter Amendment. The Charter Amendment is filed as Exhibit 3.1 to this Current Report on Form 8-K and is incorporated in this Current Report on Form 8-K by reference.

In connection with the Charter Amendment, on August 1, 2025, the Array Board adopted the Amended and Restated Bylaws of Array (the “A&R Bylaws”) to reflect the Name Change. In addition, the A&R Bylaws (a) delete the reference in Section 3.5 to the Long-Term Incentive Compensation Committee of the Array Board and (b) delete the provision in Section 2.2 that prescribes a fixed range for the number of members of the Array Board. The A&R Bylaws are filed as Exhibit 3.2 to this Current Report on Form 8-K and are incorporated in this Current Report on Form 8-K by reference.

Item 7.01. Regulation FD Disclosure

On August 1, 2025, Array and TDSissued a joint press release announcing the Closing and related matters. A copy of the press release is furnished as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated into this Item 7.01 in this Current Report on Form 8-Kby reference.

Item 8.01. Other Events