Hedge funds arbitrage techniques, usually when extremely high correlation between the two products, the price unreasonably relationship, fund buying on the side of the low price of the product, while selling high priced products to lock which spreads profits, when the relationship between the two products returned to normal, you can achieve a profit. So that the fund can buy, but also venting their investment in addition to the general stock manipulation tools, but also including futures, options and other kinds of derivative products. The most common subject of arbitrage including interest rates, exchange rates, convertible bonds, merger and reorganization of enterprises.