India's markets regulator has widened an investigation into alleged market manipulation by U.S. securities trading firm Jane Street to include other indexes and exchanges, a source familiar with the matter said.

The lawsuit alleged that the traders had stolen a “ highly valuable, unique, and proprietary ” trading strategy, which was quickly revealed to revolve around India’s booming options market. Jane Street and Millennium settled the lawsuit in December, but judging from SEBI’s report it has cast a long (and expensive) shadow.

SEBI has temporarily barred Jane Street from the Indian stock market and impounded ₹4,840 crore for alleged index manipulation, raising concerns about retail traders' vulnerabilities in derivatives trading.