T-Mobile Vice Chair Mike Sievert Resigns From Board, Effective November 1, As His Contract Amendment Expires

G. Michael Sievert, Vice Chair of T-Mobile US, told the board on Monday that he is resigning from it, effective November 1, according to an 8-K the company filed Wednesday. The company said the exit involves no disagreement with it.

Exit timed to a contract's end

Sievert notified the board of directors on October 26 of his decision to step down from the board and from its Transaction Committee. The company said his resignation date lines up with the expiration of a September 19, 2025 amendment to his Amended and Restated Employment Agreement, which is dated March 9, 2023.

On the same November 1 date, Sievert will also cease to serve as Vice Chair of the board and of the company.

The filing states that his resignation is not the result of any disagreement with the company on any matter relating to its operations, policies or practices.

The company he is leaving

T-Mobile US sells wireless phone and broadband internet service, along with phones, tablets, wearables and accessories, under brands including T-Mobile, Metro by T-Mobile and Mint Mobile. It also offers device protection, financial services and advertising.

As of December 31, 2025, it served 142.4 million customers and employed approximately 75,000 people, according to its annual report. In 2025, postpaid customers, who pay after receiving service, generated 81% of service revenues, while prepaid customers, who pay in advance, generated 15% and wholesale and other services 4%.

What changes on November 1

Three roles end that day: Sievert's board seat, his seat on the Transaction Committee and his Vice Chair title. The filing was signed by Chief Financial Officer Peter Osvaldik on October 28.

Sievert's board seat, committee seat and Vice Chair title all end on November 1, the day his contract amendment expires.

Sources

• 8-K Filing — T-Mobile US, Inc. (TMUS) — SEC EDGAR