Sam..

The price drops as soon as a short sale occures..as stock price falls on a sell function..

Short selling is neither terribly complex nor entirely simple. In other words, it's a concept that many investors have trouble understanding. In general, people think of investing as buying an asset, holding it while it appreciates in value, and then eventually selling to make a profit. Shorting is the opposite: an investor makes money only when a shorted security falls in value.

Short selling involves many unique risks and pitfalls to be wary of. The mechanics of a short sale are relatively complicated compared to a normal transaction. And, as always, the investor faces high risks for potentially high returns. It's essential that you understand how the whole process works before you get involved.

Rather that try to explain it more here go here and read all about it..

http://www.investopedia.com/universi...