A day after Softbank Corp. said it was buying a majority stake in Finnish game maker Supercell, the company's billionaire chairman and CEO, Masayoshi Son, is at it again.

The nation's third-largest wireless carrier is also in talks to buy a stake in Brightstar Corp., a U.S.-based mobile phone distributor, Softbank said in a filing to the Tokyo Stock Exchange. The Nikkei newspaper earlier reported that deal could be worth more than ¥100 billion.

Softbank has been involved in at least 12 deals in the past year, topped by its $21.6 billion (¥2.1 trillion) acquisition of U.S. telecommunications firm Sprint Corp., as it looks to expand in North America and Europe to counter a declining population at home.