In trading systems and the markets there are two ways to enter the traditionally used, buying a security at a specified price with the intention to appreciate, to later sell at a higher price than we bought it, and make the difference between purchase and sale securities denominated in language as long, or because over time the stock market has evolved, adopting new possibilities for trading, with so-called short positions or down.
Consisting reverse the above concept, enter the market sold with the intention that the market down, and subsequently purchase, with the corresponding benefit of the difference in sale and subsequent purchase.
In summary, the first transaction is the sale of value that have been provided by brokers or institutions, to be repaid with the purchase of a future price that may be higher or lower, if low will profit by the difference and if quote raises the value will get lost by that difference.
These new possibilities of entering the market and make trading, allow the use of new investment strategies, in order to take advantage of all movements in the markets, providing greater market liquidity and volatility.
This is because whenever you want to take a position has to be the counterpart, if one wants to buy, there must be someone who wants to sell and vice versa, otherwise there would be no liquidity.
The rules and regulations in the markets by the supervisory bodies is latent in these types of positions, for proper use.
Of the most used for performing positions is type products are Futures and CFDs, ETFs or even there Hedge Funds, reverse that gain or lose in this way.
Short positions, despite his speculation with systems that take advantage of these movements can serve hedge against the fall in previous positions in the portfolio to neutralize the movement.
For trading systems allow them more dynamic and frequency of operations, in order to obtain returns in all market movements, and especially intraday systems that open and close positions in the session.
Markets and products evolve to provide greater service and trading opportunities to investors with increasingly easy to reach any particular platforms you want, previously unthinkable because of the difficulty of access supposed.