Arthur Levitt Jr., a former chairman of the Securities and Exchange Commission, has said in explaining Rubin's strong opposition to the regulations proposed by Born that Greenspan and Rubin were "...joined at the hip on this. They were certainly very fiercely opposed to this and persuaded me that this would cause chaos." However, in Rubin's autobiography, he notes that he believed derivatives could pose significant problems and that many people who used derivatives did not fully understand the risks they were taking.