What is Jane Street? And why are regulators watching it?

The people at Jane Street are often described as mathematical. A lot of them play poker. They have um they have puzzles in their offices. Um they're problem solvers in the most advanced way.>> And those puzzle playing problem solvers spend their days helping institutions and other investors make trades. Essentially, they're matching a buyer and a seller. You think that when you place an order that that order just it's as if you go to the grocery store and you're buying something.Well, in the markets, there ...