I saw three people: one for a logic problem/analytical thinking test, another for a C++ technical test, and a third for a review of my CV. The first two sessions went really well; the third was a disaster. I was asked the same question repeatedly, despite my making clear that the answer required in-depth business knowledge that I never claimed to have. I said I was ready and willing to learn, but I couldn't give answers off the top of my head on a subject about which I know little, that others have spent a university career learning. Most of the people I met (on this and other occasions) were great to meet - this last guy was on an ego trip and ruined my opinion of his firm.

Describe the Black-Sholes model.