Trading Intern

Resume screen followed by a phone interview. Recruiter said it was technical but they just asked questions about my resume and similar behavioral questions. Flew to Citadel HQ in Chicago for onsite consisting of 3 interviews (initially 4 were planned but one didn't show up) 45 minutes each. First was basic probability questions, second was faster paced mental math and probability (some without pen and paper) and for each answer, they asked for a 95% confidence interval, and third was a challenging probability problem and an algorithmic problem. Interviewers were very friendly and helpful.