It takes 1 day if you fail the test like I did. Questions are ridiculous - undergraduate material - although as already mentioned they ask you to read books about portfolio management. I do not know why G research are wasting their candidates time. I have no idea what is the point asking a PhD from a top 50 university in the world these type of questions - obviously if you have degree from Oxford or Michigan it is highly unlikely that you will not be able do understand basic maths like linear algebra or some obscure corner of statistics - the point of your good education is that you have seen these things already and you will be able to remind them in 30 mins time if necessary. If I have to be honest, nobody of the really smart people around the world remembers all details of their field - the point is to have seen them. But G research obviously would like to find somebody who can multiply 5 digit numbers in their head while doing one-arm pull ups with one hand and writing operas with the other. Good luck in finding such a PhD - but please do not lose everybody else's time.

One 90 minutes exam. It was to be followed by face-to-face interviews. As noted by others here, the exam is lengthy and I failed. From there they walked me to the door. Even though I failed, I'm rating the exam average difficulty because the concepts needed are very very basic. But you have to be able to do many calculations without mistakes from beginning to the end, and quickly. I'm also rating the overall experience negative only because being my first interview ever I expected that at least gain experience with face to face interviews, but unfortunately I didn't even get that far.

In house exam, which is very tough, covers a broad range of questions. Due to non-disclosure agreement, I can't say anything about it. But it is very hard to cover all the fields. It's worthwhile go to one of the presentations on campus. They are quite helpful and may answer some of your questions in general.