Bharara, 48, has made a national and international mark for himself with many high-profile cases and investigations including foreign countries, insider trading and those involving US politicians.
Promoters and top executives intending to buy or sell shares of their companies might soon have to inform the market well in advance for such transactions.
The FT report said the existence, size and investments of the highly profitable internal trading fund, which was set up three decades ago, have until now remained largely unknown outside a circle of former and current insiders.
Prominent Indian-American attorney Preet Bharara has no plans to quit as the chief federal prosecutor in Manhattan anytime soon as he has the "greatest job in the world" but said he will "walk the earth and get into adventures" whenever he retires.
Every move that strengthens Cyrus Mistry's position in companies like Indian Hotels could prolong the uncertainty.
"I did not resign. Moments ago I was fired. Being the US Attorney in SDNY will forever be the greatest honour of my professional life," Bharara tweeted from his personal verified Twitter account, making a reference to his jurisdiction the Southern District of New York.
The former McKinsey India head is presently on board of many big Indian conglomerates.