Srini Gopalan, named T-Mobile’s next CEO on Monday morning, speaks at a T-Mobile event in June. Gopalan, 54, joined T-Mobile as COO in 2023 after five years on the board. Once the scrappy outsider, T-Mobile is now the largest U.S. telecom company by market capitalization, ahead of AT&T and Verizon. T-Mobile CEO Mike Sievert will become vice chairman, continuing to serve on the management team. Sievert, a 13-year veteran of the company, has been a central figure during the Un-carrier era.