Large buy or sell orders—executed seconds before close—nudge prices just enough to swing the outcome of options and futures contracts. It’s subtle. It’s fast.

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.

SEBI has barred US-based Jane Street Group from participating in the Indian stock market and ordered it to disgorge unlawful gains of ₹4,843 crore for allegedly manipulating stock indices through derivative positions.