Cantor Fitzgerald, with about $200 million of capital and 2,000 employees, is the biggest broker in the $3.3-trillion U.S. Treasury securities market, matching buy and sell orders among the 37 firms that underwrite the majority of the government's debt. Under Cantor's stewardship, Cantor Fitzgerald also became the first Wall Street firm to offer global electronic access to the U.S. Treasury markets 24 hours a day.

Just two months ago, Cantor and his wife, Iris, settled a dispute over control of Cantor Fitzgerald. The firm's management moved to declare Cantor incapacitated and have Howard Lutnick named managing general partner. The Cantors fought that move in court briefly before agreeing to a settlement that solidified Lutnick's position. The Cantors' 55% family stake was converted to a new limited-partnership interest and they withdrew as general partners.