SN Subrahmanyan will take charge as the CEO and MD of Larsen & Toubro from Saturday, which will also mark the end of nearly two-decade long tenure of AM Naik at the helm. The appointment was approved by the company board on April 7 and marks a major change in leadership positions at L&T where Naik has served for over 52 years, including as its head for over 17 years, the company said in a statement.Subrahmanyan is currently the deputy MD and president of the company .The board had also requested Naik, group executive chairman, to provide guidance and mentorship to the company's leadership subsequent to his current term. He will assume the new role of non-executive chairman for a period of three years beginning October 1, immediately upon his retirement as executive chairman on September 30.