Mumbai: Gautam Adani’s flagship, Adani Enterprises, has initiated its much-awaited follow-on public offer (FPO) to raise as much as 20,000 crore ($2.5 billion) from retail and institutional investors, riding on the meteoric 26-fold jump of its stock prices, said multiple persons in the know. The company has mandated Jefferies and ICICI Securities, the people cited said.