Their ban from India isn't particularly sinister. What they did would have been perfectly legal here in the US as "supplying liquidity". They just successfully arbitraged the liquidity gap between the Indian options market and the long position stock market.

No, this type of "liquidity arbitrage" is market manipulation, and illegal in the US.

eg: https://www.sec.gov/enforcement-litigation/litigation-releas...

> The cross-market manipulation involves buying and selling stocks at a loss, allegedly for the purpose of moving the prices of corresponding options, so that Avalon could make a profit by trading those options at artificial prices.

> The Court found that the two alleged manipulative trading schemes-if proven-would violate Sections 10(b) and 9(a)(2) of the Exchange Act and Section 17(a)(1) of the Securities Act.

or https://www.google.com/search?client=firefox-b-1-d&q=banging... per https://www.steel-eye.com/news/jane-street-fine-566.3m-marke...