Mitsubishi Securities Co. began operations Monday after being launched over the weekend by Mitsubishi Tokyo Financial Group Inc. through the merger of four affiliated brokerages.

The huge brokerage the fourth-largest securities house in terms of assets after Nomura Holdings Inc., Daiwa Securities Group Inc. and Nikko Cordial Corp. is expected to heighten competition in the industry.

"Mitsubishi Securities has become a core brokerage in MTFG, which consolidates investment banking operations," Nobuo Nakazawa, president of Mitsubishi Securities, said at a commemoration ceremony Monday at its head office in Tokyo's Marunouchi district. "We will aim to be a leading company in the industry with the top Mitsubishi brand."