India’s securities regulator plans to boost its surveillance systems to better detect complex trading strategies after taking action against high-speed trading giant Jane Street Group for alleged market manipulation.

India has temporarily barred Jane Street Group LLC from accessing the local securities market for alleged index manipulation, dealing a severe hit to the US firm that made $4.3 billion in trading gains there in more than two years.

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.