The Case-Shiller data for August came out this morning, and based on this information and the September 2013 Zillow Home Value Index (ZHVI, released Oct. 17), we predict that next month’s Case-Shiller data (September 2013) will show that both the non-seasonally adjusted (NSA) 20-City Composite Home Price Index and the NSA 10-City Composite Home Price Index increased 13.2 percent on a year-over-year basis. The seasonally adjusted (SA) month-over-month change from August to September will be 0.8 percent for both the 20-City Composite and the 10-City Composite Home Price Indices (SA). All forecasts are shown in the table below. Officially, the Case-Shiller Composite Home Price Indices for September will not be released until Tuesday, Nov. 26.
The Zillow Home Value index showed the first signs of moderation in home value appreciation, with several of the largest metros showing month-over-month declines in September. Case-Shiller indices have also shown slowdowns in monthly appreciation but have not yet recorded monthly declines. Even when the Case-Shiller indices do show monthly depreciation in some areas, they will continue to show an inflated picture of home prices, especially when considering year-over-year growth. The Case-Shiller indices are biased toward the large, coastal metros currently seeing enormous home value gains, and they include foreclosure resales. The inclusion of foreclosure resales disproportionately boosts the index when these properties sell again for much higher prices — not just because of market improvements, but also because the sales are no longer distressed.
In contrast, the ZHVI does not include foreclosure resales and shows home values for September 2013 up 6.4 percent from year-ago levels. More on the differences between a repeat sales index, including the Case-Shiller indices, and an imputed hedonic index like the ZHVI can be found here. We expect home value appreciation to continue to moderate through the end of 2013 and into 2014, rising 3.8 percent between September 2013 and September 2014 — a rate much more in line with historic appreciation rates. The main drivers of this moderation include rising mortgage rates, less investor participation – leading to decreased demand – and increasing for-sale inventory supply. Further details on our forecast of home values can be found here, and more on Zillow’s full September 2013 report can be found here.
To get some sense of where the Case-Shiller Composite-20 Index will go over the coming years, this chart combines: 1) the historical trajectory of the index; 2) next month’s forecast given above based on current Zillow data; and 3) Zillow’s forecast for real estate appreciation over the next five years, based on the Zillow Home Price Expectations Survey, which includes input from more than 100 economists. These panelists actually predict the five-year path of the ZHVI, not the Case-Shiller index, but the future expectations are interesting nonetheless when applied to the current Case-Shiller index levels. The latest Zillow Home Price Expectations Survey (2013 Q3) came out in early August, and the next one will be released in November.
To forecast the Case-Shiller indices, we use the August Case-Shiller index level, as well as the September Zillow Home Value Index (ZHVI), which is available more than a month in advance of the Case-Shiller index, paired with September foreclosure resale numbers, which Zillow also publishes more than a month prior to the release of the Case-Shiller index. Together, these data points enable us to reliably forecast the Case-Shiller 10-City and 20-City Composite indices.