O'Connor & Associates was a Chicago-based options trading firm, with particular emphasis on financial derivatives. The firm was acquired by Swiss Bank Corporation (later merged with Union Bank of Switzerland to form UBS). O'Connor was headquartered in Chicago and occupied the former offices of the Chicago Board of Trade. At the time of its acquisition by Swiss Bank Corporation, O'Connor had over 600 employees worldwide, 230 of which were based in Chicago. The remaining 400 employees were involved with O'Connor's Swiss Bank joint venture, which was formed in 1989.'.