" 'Ethical' is the term I think of when I think of Duke," said Philip Clarke III, a managing director of the reconstituted Chicago Corp. "There was Duke; there was Jay Buck, who had been at Northern Trust; there was Faris Chesley. These guys all ended up taking up a piece of what Jack's job was in terms of being captain of the ship." In leading Shearson Hammill in New York before it merged with Sanford Weill's Hayden Stone Inc. in 1974, Mr. Chapman was at the center of a network of brokers, and that post prepared him well for bringing together members of the Chicago Board Options Exchange, his son said. Members owned the exchange before it became publicly traded CBOE Holdings Inc. in 2010. Mr. Chapman was followed as CEO at the exchange by Bill Brodsky, another New Yorker who still serves as CBOE's chairman and CEO. "He recognized the need for options education and the inevitability of electronic markets, and initiated plans to develop each," Mr. Brodsky said of Mr. Chapman in a statement released by CBOE.