The bank will combine Mizuho Securities with Shinko Securities, in which it owns a 26 per cent stake, in January of next year.
Mizuho said that the merger would create Japan's third largest brokerage, beating Nikko Cordial Corporation in terms of revenue.
Commenting on the plans to reporters, Mizuho Securities vice chairman Keisuke Yokoo said that he hoped to see the merger mark an expansion to Mizuho's investment banking business abroad.
"Our goal is eventually to compete on an even footing with Wall Street banks," Mr Yokoo said, according to Reuters.
"If more mergers and acquisitions are needed to achieve that goal we'll consider it."
Mr Yokoo, who is due to become the head of the new brokerage following the merger, added that he would not rule out acquisitions in the US to fulfill this goal.