The online coding challenge (on hackerrank) was quite standard, they gave a time sequence of stock pricing and a list of buys/sells for several people (at different times), and asked you to identify those trades that lead to a large gain (or avoided a large loss) within 3 days of the trade. Afterwards they gave me a phone call asking where my interests were, but for some reason I didn't seem to have a very productive conversation with the interviewer, perhaps we just didn't get along that well (the fact that it was a phone call and not Skype/face-to-face probably contributed). They asked a lot of "why" questions (Why did you study CS, why did you choose to work on xxx... why do you not like xxx...) and to me there's no good "why" to a lot of these things (I mean, I do what I like, and I either like something or I don't). I'd've preferred it if they'd asked me directly what fields I am interested in, examples of projects I would / would not be interested in, etc. In the end they sent an email saying they didn't have a suitable position for me, which was kind of unfortunately as Palantir was actually one of the companies I was more interested in at that time.