I am starting to study mathematical finance. When I studied microeconomics and macroeconomics I studied utility functions, but I never saw how they are in the real world. I do not see how they can be used since a utility function is very personal, and there are many stereotypes of investors: HFT firms, swing traders, day traders, etc., and their behavior not necessarily match the risk-averse behavior represented with convex functions. As an example, it is the case of companies such as Apple Inc. and netflix.com Inc. with prices $225.74 \$ $ and $374.13 \$ $ respectively, but the solvency, profitability and operating efficiency of Apple Inc.'s are better than netflix.com Inc.'s.
I wonder if utility functions are really used by hedge funds, banks, etc., to compute the price of financial instruments?
Thanks in advance