Your company progress is tracked by your stock value. As your company value increases so does your stock price. Expand your airline in all direction to raise your stock value. Add airplanes, routes, employees, save fuel money. Be sure to buy your friends stock when it is available and encourage them to keep their stock prices up so that your investment in their airline grows.
Stocks are also the social element in the game. Since this game is on facebook it's cool that there is a communication element. As a share holder you may get messages from the companies (people) you are invested with.
