. ▁ ▁C ohen ▁would ▁remain ▁with ▁the ▁firm ▁through ▁its ▁various ▁mer gers ▁in ▁the ▁ 1 9 7 0 s , ▁including ▁She ar son , ▁Hamm ill ▁& ▁Co . ▁and ▁Lo eb , ▁R ho ades , ▁Horn b lower ▁& ▁Co . ▁ ▁In ▁ 1 9 7 8 , ▁C ohen ▁left ▁She ar son ▁for ▁one ▁year ▁to ▁work ▁for ▁Ed mond ▁Saf ra ▁at ▁Republic ▁New ▁York ▁Corporation ▁and ▁the ▁Trade ▁Development ▁Bank ▁before ▁returning ▁to ▁She ar son ▁in ▁ 1 9 7 9 . ▁She ar son ▁merged ▁with ▁American ▁Express ▁in ▁ 1 9 8 1 ▁at ▁which ▁time ▁C ohen ▁became ▁president ▁and ▁chief ▁operating ▁officer ▁and ▁in ▁ 1 9 8 3 ▁chairman ▁and ▁chief ▁executive ▁officer . ▁ ▁At ▁age ▁ 3 6 , ▁C ohen ▁was ▁by ▁far ▁the ▁young est ▁head ▁of ▁a ▁major ▁Wall ▁Street ▁firm . ▁In ▁ 1 9 8 4 ▁C ohen ▁acquired ▁Le h man ▁Brothers ▁Inc . ▁▁ ▁In ▁ 1 9 8 8 , ▁C ohen ▁was ▁a ▁key ▁player ▁in ▁the ▁lever aged ▁buy out ▁of ▁R J R ▁N ab is co . ▁ ▁C ohen ▁and ▁She ar son ▁Le h man ▁supported ▁the ▁company ' s ▁CE O ▁F . ▁Ross ▁Johnson ▁in ▁a ▁proposed ▁$ 1 7 ▁billion ▁buy out . ▁ ▁Ult imately , ▁Johnson ▁and ▁C ohen ▁lost ▁their ▁bid ▁for ▁the ▁company ▁and ▁R J R ▁N ab is co ▁was ▁acquired