What's the grumpy version of xkcd 1053? Anyway, Jane Street does high frequency trading on Wall Street, and they're kind of a big deal in that sector. They date back to 1999, with some IBM people. Other than the money, the reason they're interesting for HN is they're an OCaml shop and do a lot for that ecosystem. So if you're a computer language nerd and want to work in a functional programming language, but one that has real world applications, and make a lot of money doing it, Jane Street is the place to be!