India has barred one of the world's largest quant trading firms, Jane Street, from accessing its securities market after an investigation found it made "unlawful gains", taking the most stringent action ever against a foreign trading firm.

India has barred Jane Street from the country’s financial markets and said it would seize around $570 million that the U.S. securities firm made from allegedly fraudulent trades.

The Securities and Exchange Board of India took action against Jane Street Capital. Operations in Mumbai were halted. Assets worth over half a billion dollars were seized. Analysts predict a drop in derivative market volumes.