Jane Street barred from Indian markets as regulator freezes $566M

According to Indian regulators, every trading day Jane Street would:

1) buy large volumes of stocks and/or stock futures that are part of an index tracking India’s banking sector, early in the day,

2) subsequently place large options trades, betting that the index would decline or volatility would spike later in the day, and

3) later in the day, cash out of the large long positions, dragging the index lower, making far more money on the options trades than on the long positions.

Jane Street can and likely will claim the firm was only arbitraging away pricing inefficiencies, nothing more, nothing less. It was just business as usual, etc., etc.

However, given the scale of the operation, Jane Street's actions sure look like textbook market manipulation. Calling it like I see it.

Ok, but what moron was selling them the puts , and not seeing the pattern after a couple of days of this ? Sebi logic seems questionable.

I think the point is that retail investors were selling the puts, they predictably sold every day (or more likely, they predictably bought calls which is almost equivalent), and there were no other sophisticated market makers in the market.

That changes the description of part 2 to "subsequently experience retail investors placing large options trades with them" which is much more defensible market making behaviour - their early buying was in anticipation of later demand and really did involve taking a risk.

The truth is probably somewhere in between.

To add to this, that behaviour would typically be OK in the US, with a good compliance department to keep you away from the worst of the grey areas.

If the SEC did investigate you for this, an important part of the case would turn on the extent to which your actions were "bona fide market making". And the regulator would also be more introspective about the market structure that allowed this to happen - why is there only one market maker? How did we allow a derivatives market much more liquid than the underlying?