There are two I have experience with, both with a severe fantasy slant.
The Running a Business subsection of this sourcebook for 3.5 as quite adequate rules for running a business in D&D. Given that it has rules for risk and the consequences of it, it can make for a fantastic game centered around a player-owned and run business, especially if you adopt all of the setting meta-description found in K's sourcebooks.
While it does not contain a stock market per se, the idea of selling stock and other capitalization scenarios is not too difficult to model from a player-facing perspective and could be easily patched on.
The sourcebooks City & Guild and Lords of Men explicitly explore business creation, profit and loss, risks, and stories associated with them. I've used city and guild in my game to model Covenant run businesses, and it makes for a quite engaging extension of player agency as they decide what risks, reinvestiment, and directions to take their stories in. Unfortunately, the idea of a corporation and stock does not exist in mythic Europe. It is quite possible to center an entire saga around this without involving magic at all.
The idea of Freemarket is operating a MRCZ (basically a business) in a post-scarcity sci-fi economy. Given that you are effectively performing all of the functions of a business, I feel that it meets your requirements. It would certainly be possible for the players to construct (and sell) the idea of a stock market within the station.