I applied through college or university. I interviewed at Jane Street (Durham, NC) in Feb 2013
Interview
First round on campus interview, asked three brainteasers. Second round phone interview, asked a Fermi estimation question and made theoretical trades based on my confidence in the answer to a brain teaser.
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