Former T-Mobile CEO Mike Sievert is hanging up his magenta hat, leaving the wireless giant’s board of directors and vice chair role effective Nov. 1.

Sievert will also leave the board’s Transaction Committee, according to a federal filing. His departure comes a year after he handed the CEO job to Srini Gopalan.

A company spokesperson said via email that the vice chair role was structured as a one-year term, adding that Sievert has “been a valued strategic advisor throughout the leadership transition, and we’re incredibly grateful for his contributions.”

T-Mobile said in the filing that his departure “is not the result of any disagreement with the Company on any matter relating to its operations, policies or practices.”

Sievert joined T-Mobile in 2012 as executive vice president and chief marketing officer, the same year John Legere became CEO. He later became president and chief operating officer and was mentored by Legere before succeeding him as chief executive in 2020. He served as CEO for about five and a half years.

Sievert was a central figure in T-Mobile’s campaign to brand itself the “Un-carrier.” During his time at the company, T-Mobile grew from fewer than 30 million customers to more than 130 million by September 2025, a period that included its merger with Sprint.

Once the scrappy outsider, Bellevue, Wash.-based T-Mobile currently ranks second among U.S. telecom companies by market capitalization, behind Verizon and ahead of AT&T.

Sievert previously worked at Microsoft, AT&T Wireless, E-Trade, IBM and Procter & Gamble.