G-Research Quantitative Researcher interview questions

Contacted by their HR department and asked to take a technical sit-down exam consisting of quite difficult mathematical, statistical and algorithmic questions. Signed NDA, so not allowed to disclose specifics on the questions. However, there are previous exams on their website to use for preparation. Their staff is really accommodating and helpful.

There is a ~ 1 hr exam they set up for you. It is very similar to the past exams on their website. I did reasonably well on this, and was given a phone interview. The phone interview asked a number of more open-ended but superficial questions about optimization / machine learning. At the end were two quite difficult quantitative questions. One was about probability, the other about algorithms. I did not do well enough on these questions to advance further in the process.