T-Mobile US Vice Chair G. Michael Sievert Resigns from Board of Directors

Executive Summary

On October 28, 2026, T-Mobile US, Inc. (NASDAQ: TMUS) filed a Form 8-K under Item 5.02 announcing that G. Michael Sievert notified the Board of Directors on October 26, 2026, of his resignation from the Board and its Transaction Committee, effective November 1, 2026.

Key Highlights

• Roles Vacated: Resignation from the Board of Directors, the Board's Transaction Committee, and cessation of service as Vice Chair of the Board and the Company.
• Timeline: Notice was tendered on October 26, 2026, with the resignation taking effect on November 1, 2026.
• Contractual Alignment: The effective date coincides with the expiration of the September 19, 2025 amendment to Mr. Sievert's Amended and Restated Employment Agreement dated March 9, 2023.
• Disagreements: The filing explicitly specifies that Mr. Sievert's resignation did not stem from any disagreement with the Company on any matter relating to its operations, policies, or practices.

Governance & Market Impact

• Significance: Medium. The departure completes a leadership transition timeline following Mr. Sievert's earlier role as CEO and subsequent service as Vice Chair.
• Operational Continuity: Because the exit is concurrent with the scheduled expiration of his employment agreement amendment and involves no disagreements, the market impact is expected to remain neutral to orderly.