I applied through university. The process took 1 week. I interviewed at Group One Trading (Chicago, IL) in Mar 2016
Interview
Submitted resume on campus, got a call-back a couple of days later. Had one interview with an HR person, half behavioral, half numbers. Behavioral is your standard trading interview, why do you want to be a trader, what makes you interested in trading etc. Numbers was straightforward mental math that anyone should get with moderate practice
Interview questions [1]
Question 1
Expected value of a game where heads and tails are worth certain amounts and you flip several times.