Jane Street is arguably the most prestigious quantitative trading firm in the world. Known for its intellectual culture, use of OCaml, and staggering compensation packages.
At a Glance
Compensation
Intern: $25k/month + Housing
New Grad: $400k - $600k TC
Interviews
Focus: Probability, Expected Value, logic puzzles, and betting games.
Tech Stack
Core: OCaml (Functional Programming)
Hardware: FPGA
The Interview Process
- Recruiter Screen: Basic fit. "Why Jane Street?" "Why trading?"
- Phone Interview (1-2 Rounds): Technical.
- Traders: Mental math (73 * 46), EV games ("I roll a die...").
- SWE: Coding in any language (Python/C++ ok). Standard algo/DS but harder.
- Onsite (Superday): 3-4 back-to-back interviews.
Expect "The Market Maker Game".
Example: "Market make the population of Chicago. I will buy or sell from you. Make a width."
Sample Questions
Probability: The Coin Flip
You flip a fair coin. If it lands Heads, you win $1 and flip again. If it lands Tails, the game ends. HOWEVER, if you have flipped 3 Heads in a row, the game also ends and you win nothing.
What is the Expected Value of this game?
Logic: The 100 Lockers
There are 100 closed lockers. Person 1 opens every locker. Person 2 toggles every 2nd locker. Person 3 toggles every 3rd locker... ... Person 100 toggles the 100th locker.
How many lockers are open?
Culture & Perks
- Free Food: Breakfast, Lunch, Dinner (and giant cookie trays).
- Intellectual: Chess tournaments, puzzle hunts, guest lectures from professors.
- Flat Hierarchy: Interns sit next to partners. No offices.
- Dress Code: T-shirt and jeans is the uniform.