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.

In a dramatic move that’s rattled India’s financial markets, the Securities and Exchange Board of India (SEBI) has banned the global trading giant Jane Street Group from participating in the country’s securities markets. The regulator accused the firm of orchestrating what it calls one of the boldest market manipulation schemes in Indian history.

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.