I applied through a recruiter. The process took 2 weeks. I interviewed at Jane Street (New York, NY) in Oct 2010
Interview
The first interview was three brain teasers, known basic probability and be able to explain the reasoning behind your answer and talk the interviewer through your approach. The second interview started with some basic fit questions (Why Jane St? Why Trading? Why should we hire you?) then another brain teaser.
Interview questions [1]
Question 1
What is the smallest number divisible by 225 that consists of all 1s and 0s?
Many rounds of brainteasers, some of which are more rapid fire in nature and others which require you to flesh out a detailed answer to a complex problem. Be well rested and well prepared!
mostly maths probability questions - a lot of conditional probability, relatively easy in the first round, but you need to think out loud - you need to be really fast
4 rounds in final. The first one is market making of cards. The rest are especially designed games. The interviewer may ask added question along the playing of the game