Smith joined Collins Stewart in 1992, shortly after being fired from UBS. He became a director in 1996; in 2000 he became Chief Executive after leading a management buy-out. The company floated on the London Stock Exchange in the same year. In 2003, Collins Stewart acquired Tullett Liberty, and then in 2004 acquired Prebon Group, creating Tullett Prebon, the world's second largest inter-dealer broker.
