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 (SEBI) has flagged global proprietary trading firm Jane Street for allegedly manipulating Indian stock markets in an “unusual” way.