The interview process is pretty standard to what you would expect. First, they ask you a quick behavioral and then you go straight into probability questions. I had one big question that took me the entire time (had to used LOTP coupled with some edge case work to generate infinite geom series to solve) but iv'e had buddies with 1 quick question (simple bayes rule stuff) followed by a MM game... so note it really depends on luck of the draw.

Three stages. Timed online assessment on probability, combinatorics, mental math, and estimation. Short recruiter call on fit and motivation. Virtual onsite with several 30 to 45 minute rounds on market making, risk reward tradeoffs, brainteasers, data interpretation, and teamwork. Decision in about a week.