Jane Street has been barred from the Indian securities market by its markets regulator, which has said the U.S. firm used its trading strategies to "manipulate" a key stock market index, leading to losses for millions of retail investors,

The Jane Street fallout has already taken a toll on BSE, with the shares on July 4 suffering one of their steepest declines this year — extending a slide that had already begun. The stock, whose price ballooned more than 900% over the past two years, is now down 21% from its June peak. On Friday, it closed at its lowest price in almost two months.

A temporary trading ban imposed by India’s securities regulator on Jane Street Group LLC is fueling concerns that volumes in the nation’s bustling derivatives market may drop, hurting business at the top exchange.