I applied online. I interviewed at Jane Street (Hong Kong) in Jun 2023
Interview
They asked entirely maths/probability questions, usually with some sort of coin toss/die roll element in the context of a game. Very friendly and patient interviewers, who will guide you through the questions.
Interview questions [1]
Question 1
We are playing a game where we roll two die. If the sum is even, you win and the game ends. If the sum is 7, I win and the game ends. If the sum is odd, we roll again. What is the probability that you win?
I applied online. The process took 2 weeks. I interviewed at Jane Street (London, England) in Sep 2024
Interview
1st interview: basic probability brainteasers
2nd interview: significantly more difficult game questions one involving dice and other coins. Two players roll a dice then decide whether they pick their own, other, or withhold decision until next round. What's the optimal strategy?
Interview questions [1]
Question 1
You are playing a game where you flip a coin 5 times. You win if three heads come up in the 5 coin tosses. You lose if three tails come up in the 5 coin tosses. If you win you get £1. If you lose you lose £1. Before each flip you can choose to either double the stakes from their previous value (if you win you get £2n and if you lose you lose £2n where n is the amount you get if you win beforehand) or keep them the same. Are you willing to pay £0.50 to play this game?
Flipping coins, betting on sums, products, other interesting contracts. Some amount of being smart about formulating a market making strategy. Finally, some game theory (nash equilibrium) and excel tasks. Overall very thorough and comprehensive.
