Worst interview experience. To be fair, I think I got unlucky with the interviewer but his non-professionalism was unacceptable. Background: I interviewed for a machine learning researcher position, I have 3+ yrs experience in industry, Phd in maths. The interviewer was uninterested, and seemed even a bit annoyed from the beginning; he kept interrupting me and was contesting anything I said (which I didn't mind that much, I was happy to provide some arguments to support my claims). He then gave me some basic undergrad math questions, calculations I haven't done for like 10 years so I was a bit dusty. For the first one, I knew how to derive the result, but was just not remembering a formula he was looking for, took me like 2 minutes to get to the result, which was apparently not fast enough. At the end, he told me I need to relearn these things if I wanted to continue with the process. I asked him when was the last time he used this kind of math in his job and he said of course never...

Excellent process. Well administered interviews. Conducted at good pace and good levels of communication from recruitment. Applied online. Heard very quickly (same day). They provide comprehensive discussion of interview topics and expectations. First call with recruiter. Friendly proficient and useful. Then phone interviews. Well posed questions. Actually quite nice interviewers in comparison to a typical quant interview. I unfortunately passed the first phone interview, then did poorly on the second. Got back to me after the first interview within 2 hours and then 2-3 business days for the latter which was very appreciated from my end. Would have appreciated the opportunity to go further in the process as enjoyable interviews but can't complain at all with how it was administered.