1. Complete the online form on website
2. Received and completed a mental math quiz along with a personality test
3. Phone interview with trader
4. Web (Skype-like) interview with two traders
Still waiting for results. Questions were very math/probability based, not many behavioural questions (only one/two at the start of each interview: "Why trading"/"Tell me a bit about yourself")
Definitely practice probability brainteasers and mental math (although they only asked me two multiplication problems each interview). Be prepared for very outlandish questions such as the guessing/making bets on the population of a city and then changing your bet given something. Be ready to justify your answers - if you're stuck on something they will help you along. They never said I wasn't allowed to write anything down (besides the mental math), so make sure you do, as for the market making questions they will ask your PnL at the end of all of trades.