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.

At the heart of the controversy is Jane Street’s aggressive trading in the derivatives (futures) segment, where the firm executed trades designed not just to profit, but to sway the market itself. Here's how.