I applied online. I interviewed at Jane Street (Hong Kong) in Sep 2023
Interview
Only got to the third round, the first two rounds are about basic probability games and simple math games, like finding maximum of sum of pairwise coprime integers you can draw from 1-30. Also basic betting gaems involving coin clipping and such.
Interview questions [1]
Question 1
like finding maximum of sum of pairwise coprime integers you can draw from 1-30.
1st round--45 minute phone call purely technical with brainteasers. no behavorial besides brief introduction of self. i believe there are 2nd and 3rd round phone and a final superday but didn't make it past there.
multiple online interviews, technical in nature, followed by an in person in office interview which lasted an entire day and had multiple stations. focused on problem solving, probablity, game theory etc etc
I applied online. The process took 1 week. I interviewed at Jane Street (London, England) in Nov 2025
Interview
They started with a basic introductory question followed by some probability based stuff. Wasn’t too difficult but you have to ace it, they expect perfection. They cut the interview off at exactly 30 minutes, and will provide hints if you need it though it’s not a good sign if you need them.
Interview questions [1]
Question 1
You have 20 cards. 1 is black the rest are red. You keep drawing cards and get $1 for each red, but if you draw the black the game ends and you get nothing. How do you play and what’s the average payout? Now drawing the black card makes your score go negative, but you can continue drawing cards. What’s the strategy and expected payout now?