Complex sentence: Prominent investment banker Roger C. Altman, another Lehman veteran, left his position as a managing director of Shearson Lehman Brothers to join Peterson and Schwarzman at Blackstone in 1987, but left in 1992 to join the Clinton Administration as Deputy Treasury Secretary.
Split into simpler sentences: Prominent investment banker Roger C. Altman, another Lehman veteran, left his position as a managing director of Shearson Lehman Brothers to join Peterson and Schwarzman at Blackstone in 1987. In 1992, Altman left Blackstone to join the Clinton Administration as Deputy Treasury Secretary.