In July 2025, the Securities and Exchange Board of India (Sebi) shook the financial markets by passing an interim order against Jane Street Group, a well-known global quantitative trading firm. Sebi accused the firm and its affiliates of manipulating Indian stock index levels through a series of strategic trades designed to benefit their derivatives positions.

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.

Here's a simple breakdown of the what, why, and how of the Jane Street saga. The case finally reached the regulator SEBI on July 3, resulting in a ban on the Wa