He is considered the "father" of mortgage-backed securities, for his pioneering role in their emergence in the 1970s, during his tenure in Salomon Brothers, where he reached the position of Vice Chairman.[2][3][4] Although he was named by BusinessWeek in 2004 as "one of the greatest innovators of the past 75 years",[2] he was later strongly criticized for his role in the subprime mortgage crisis of 2007–09.[3][4]