SoftBank Group Corp. profit rose as the mobile carrier and Internet investment company boosted Japanese wireless subscribers, offsetting losses at its Sprint Corp. unit in the U.S.

The company founded by billionaire Masayoshi Son had operating income of ¥342.2 billion ($2.8 billion) in the three months to September, it said Wednesday. That compares with the ¥336.3 billion average of five estimates compiled by Bloomberg.

Son has built SoftBank into one of the world's most acquisitive companies, plowing cash from mobile phone operations and borrowing into more than 1,000 companies from Alibaba Group Holding Ltd. and Sprint to games-maker Supercell Oy and India's Snapdeal.com.

Returning to profit at Sprint, the No. 4 U.S. wireless carrier, has become a challenge for Son, with costs mounting to get and keep subscribers.

"Sprint's strategy is to trade losses for subscriber gains," Hideki Yasuda, an analyst at Ace Research Institute in Tokyo, said prior to the announcement.

"While this has worked so far, it's still too early for praise. SoftBank's resources are tied up with Sprint, so they can't make big moves in the domestic operations."