Sprint and T-Mobile are reportedly working to save their merger after earlier talks failed. The wireless carriers could announce a deal within weeks as Sprint considers a new offer from T-Mobile, according to a report by The Wall Street Journal’s Ryan Knutson and Dana Mattioli on Thursday. Sprint shares gained as much as 5% in extended trading, while T-Mobile rallied 3%. Nikkei reported earlier this week that talks ended after SoftBank, the Japanese telecom company that owns Sprint, insisted on retaining a controlling stake in the combined firm. Deutsche Telekom, T-Mobile’s owner, showed interest in taking control but was rebuffed, the report said. SoftBank looked into buying T-Mobile as far back as 2014 but backed down after telecom regulators made it clear they would block any acquisition of the fourth-largest US carrier.