Mitsubishi UFJ Securities Co., the brokerage unit of Japan's biggest bank, hired William Mumma to head its U.S. business as the company aims to expand overseas.

Mumma, 48, will become chief operating officer at Mitsubishi UFJ Securities (USA) Inc. later this month and chief executive as early as next year, said Susumu Taroura, a Tokyo-based spokesman at the brokerage unit of Mitsubishi UFJ Financial Group Inc.

Mitsubishi UFJ has begun to hire more non-Japanese bankers for top executive positions abroad. In May, the brokerage named Clifford V. De Souza the first non-Japanese chief executive officer of its European investment banking and brokerage business.