The Archetypes at all Quant Firms (Janestreet, HRT, Citadel, SIG)

Source: Talking to people / reaching final rounds / getting offers / interning at these firms

Jane Street: The Savant

Jane street gives WAY more first rounds than any of the other firms, but that doesnt make it easier. With three rounds before the final round day, they are looking to sift through as many people as possible to find that one piece of gold (the savant). The savant may not necessarily have the most textbook background but they are undeniably a genius. They can instantly look at a complex problem and find some unintuitive reduction that makes it trivial. Likely, they can quickly do mental arithmetic too. They quickly process information and have it neatly arranged in their brain. In short, they are wickedly sharp.

Citadel: The Cookie Cutter 

With the largest intern class of any of these firms, Citadel needs to apply scale to their recruitment process. They do this, by finding any students which fit their mold: Some olympiad experience in highschool, target school, took hardest classes in college and did well. They even ask their interns which classes they should search for as well. In the interviews, you will be tested rigorously on your fundamentals. If you have a strong understanding, you are likely to get the offer. 

Hudson River Trading: The Oracle

Being so new on the stage and growing so rapidly, there is not as much data on what HRT likes, and how long it will remain this way. That being said, they seem to require extremely solid CS fundamentals, as well as the ability to, on occasion, have an epiphany. While Jane Street wants someone that can look at 1000 problems and find the .1% best solution to each, HRT wants someone who can look at 1000 problems, and find the 1 in a million best solution to just one. They value great depth in a particular research field/ subdomain as well. In short, they want an Oracle who can occasionally summon a stroke of genius.

Susquehanna (SIG): The Cheeser

All the "we love gamers" stuff on their website is not just marketing. Sig wants someone with an innate sense for games - someone who can quickly calculate the game theory optimal solution for a game, but then look their opponent in the eye, see a twitch, and know when to cheese them.  Their final round includes playing games with other candidates, many of whom are highly ranked in chess, poker, and even League. Beat them all, and they will be convinced that you can cheese other market participants as a full time trader.

Akuna: The Human VLOOKUP

If you can process a huge amount of information manually without particular depth, Akuna is the place for you.

Five Rings: The JV Jane Streeter

It is actually probably just as prestigious / pays as well but being a Jane Street spinoff, I thought it was a funny name.

Comment blurbs for firms I left out (e.g. Jump, DE Shaw, etc)!