Applied online, got an email a few days later asking for a 1st round phone interview. Simple questions - "why do you want to be a trader", "what's been going on with the markets", "tell me the last trade you made". Couple resume questions. No math, probability, or brainteasers.
2nd round phone interview was with the co-founder. Also very easy. Asked some of the same questions as the 1st round. No quantitative/brainteaser questions.
3rd round was in-person in NYC. I was coming from California, requested a plane ticket and they denied the request. Decided to delay my interview by 2 weeks when I would be on the east coast and they didn't seem happy about that.
Got to the office, asked for a bottled water and was told they don't have any. Waited for 20 minutes past my appointment time, was shown to the office of the other co-founder and he says "so, let's not waste any time. tell me what I can do for you." By this point I was pretty disgusted with what I saw so I pretended not to have my resume with me, which is obviously a huge blunder.
Received an offer via e-mail 5 days later - asking me to pay them several thousand dollars!