the stadium opened as safeco field, with the locally based safeco insurance signing a 20-year contract to place its name on the stadium. with the contract ending after the 2018 season, safeco chose not to renew it. the team then signed a new 25-year naming rights contract with wireless carrier t-mobile us, the main american arm of german telecom giant deutsche telekom. the new name took effect on january 1, 2019.