(See recent posts on Phoenix Case-Shiller Home Price Index.)
The Case-Shiller Housing Index is the most accurate dataset of home prices, however, it is slow. The median home price, which is less accurate, comes out about 6 weeks before the Case-Shiller data.
The price decline per month has averaged 0.7% per month since September 2006. The decline from July to August, at 0.92%, is larger than trend but not the largest single month decline over that period which was in February 2007 (0.98%).
You can see in the graph below that the decline has been straight line so far, not accelerating nor decelerating. However, we know from already released median home price data that September will show a sharper price decline. It’s very likely to be above 1%. The “sub-prime meltdown” in August will be reflected in the September index.