I'd say 2 of the 3 criteria are needed to work in SF finance sector. I cannot put numbers to the question that you mentioned but the sector is definitely not big. Big companies off the top of my head would be Wells, BGI, Schwab, and a lot of small M&A, venture capital, private equity firms. There are big banks that also have presence in SF such as MS, Goldie Stix, and Bear but mainly in I-banking sector. Also, KMV moodys and Barra (in berkeley) are fairly quantitative. There are also mutual funds and long short equity funds in the bay area. Most of them however focus on fundamentals rather than being a quant fund. I can't really comment on whether it is "cutting edge" or not since it depends on the person. If you think default probabilities are cutting edge then you might think KMV is fairly competent. Also, BGI is decently quantitative. As far as it being NY/London cutting edge in terms of quantitative, then I think you are better off going to work in London. As I mentioned before, bay area finance is pretty fundamental. There are exceptions of course. Lifestyle is rather different. 8-9 hour days are pretty common in SF. I would say the hours in NY is closer to 9-12 hour days depending on where you work. My work hours in NY now ranges from 12-16 hour days but the group is just rather understaffed and over worked. I cannot vouch for London as I never worked there. Competitiveness varies within groups and sectors within finance. Overall, I would say that no matter what, you still need to pull your own weight and then some. Pay is definitely less in SF than in NY and London. But most are satisfied since they enjoy the corporate environment more.In my honest opinion, if you have the choice, work in London during your younger years. SF is a good environment, but I think during years when you are still learning, it is better to get exposed to more and build more connections in a big firm.