Trade Forex - Forex Market

Convergence by convertibility is critical in all futures trading, but it is especially significant with financial futures. This is because instruments such as Treasury bond futures and Swiss franc futures not only assure convertibility, but also assure the value of the conversion. If a trader takes delivery of 125,000 Swiss francs, they will have the same value as the underlying "cash" Swiss franc, no more or less.
With forex trading currency futures, there is no question about delivery, transportation, storage, or grade. You can be assured that the full value of the currency will be deposited in your account a few days after the last trading day. With value of conversion thus guaranteed, the cost and the risk of arbitraging mis-priced instruments is practically non-existent. As a result, the various exchange-traded derivatives of an underlying currency almost always have high correlation coefficients.

Source: http://www.forexinstitute.net/forex_trade/forex_concept.shtml