Jane Street has been barred from the Indian securities market by its markets regulator, which has said the U.S. firm used its trading strategies to "manipulate" a key stock market index, leading to losses for millions of retail investors,

Whether arbitrage or manipulation, the Jane Street episode highlights a critical truth: markets need more transparency, more accountability, and more human judgment.

The drama has thrown a bright light on Jane Street, a company of legendary opacity even in an industry that prioritises secrecy. And it could carry political and regulatory consequences, not just for Jane Street,