Pending Home Sales economic indicator and forex trading

The pending home Sales is yet another important index, which is published by national alliance of Realtors. The main job of this index is to provide the details of homes that are going to be sold soon. The main sources of data for this index are brokers and real estate agents. The data is usually a collection when the contract of sale is being signed, and hence it becomes an efficient and reliable index for the housing market. In about two-month time periods, the pending home sales turn into real home sales, and then this index gives more accurate results.
The question is that how does the pending home sales index actually works? When one party accepts the sales contract, it is then quoted as a pending home sale. This index is weighed higher among other similar indictors because it just takes the samples from the 20% population of the market. Later, the remaining 80% of pending sales are added into actual sales after 2-3 months.
The index takes a base year of 2001 its base value is 100. The high volume of sales was in 2001 when this index was started.
In August 2011, the data of pending home sales was released and according to expectations it has to be around 4%. However, when the real figures came out, it only showed 2.6% decrease from the last month data. This result was less than anticipated.
There was a decrease of 46 pips in the value of Dollar against the Euro and also around 36 pips against the value of GBP. As a result, the S&P index dropped around 0.6%, which was after a ten week high position.