Its kinda like buying on the up swing but when u short a stock u are actually borring the share at now prices then selling at the later prices brokers do this 2 keep the matket shares at an active volume example u short 100 shares of a stock at now price of 10 buckas a share, the stock goes down 5 bucks and u cover it then u would make a profit of 500 bucks, but if stock goes up 2 bucks u would be down 200 etc etc etc sorry but thats the best i can explain it just research in the university in the game and it will help u GOOD LUCK