You use the stock market to buy and sell diamonds, gold and coffee to reach 10 e 300 money, than upgrade all your girls to the maximum (yes, there is one) of 56.750 levels (that's the sum of all girls combined) and then you sell for double shares, which should net you... well, 'trillions of shares'. ^^ This would take several weeks of playing the stock market, though, depending on how much time you invest into the game per day. (Might even be as much as two months.)
So... those are the basics of stock market runs. Any questions? xD