Housing Price Index | Fastest Housing Price Change

The Housing Price Index (HPI) is a broad measure of the movement of single-family house prices. It serves as a timely, accurate indicator of house price trends at various geographic levels. It also provides housing economists with an analytical tool that is useful for estimating changes in the rates of mortgage defaults, prepayments and housing affordability in specific geographic areas. The HPI is based on data developed by the Federal Housing Finance Agency (FHFA) using data provided by Fannie Mae and Freddie Mac.

The HPI is a measure designed to capture changes in the value of single-family homes in the U.S. by state and metropolitan area. The HPI equals 100 for all MSAs in the first quarter of 1995. States and divisions are normalized to 100 in the first quarter of 1980. The difference in normalization dates has no impact on appreciation rates obtained from the index. HPI data are estimates subject to errors of estimation.

Transactions Covered by HPI
The House Price Index is based on transactions involving conforming, conventional mortgages purchased or securitized by Fannie Mae or Freddie Mac. Only mortgage transactions on single-family properties are included. Conforming refers to a mortgage that both meets the underwriting guidelines of Fannie Mae or Freddie Mac and that does not exceed the conforming loan limit. For loans originated in 2009, the loan limit has been set by the American Recovery and Reinvestment Act of 2009. That Act, in conjuction with prior legislation, allows for loan limits up to $729,750 for one-unit properties in certain high-cost areas in the contiguous United States.

The purchase-only and all-transactions HPI track average house price changes in either repeat sales or refinancings on the same single-family properties. The purchase-only index is based on more than 7 million repeat sales transactions, while the all-transactions index includes more than 50 million repeat transactions (includes refinance appraisals). Both indexes are based on data obtained from Fannie Mae and Freddie Mac for mortgages originated over the past 39 years.

How the HPI is Computed
The HPI is a weighted, repeat-sales index, meaning that it measures average price changes in repeat sales or refinancings on the same properties. This information is obtained by reviewing repeat mortgage transactions on single-family properties whose mortgages have been purchased or securitized by Fannie Mae or Freddie Mac since January 1975. The HPI is updated each quarter as additional mortgages are purchased or securitized by Fannie Mae and Freddie Mac. The new mortgage acquisitions are used to identify repeat transactions for the most recent quarter and for each quarter since the first quarter of 1975.

Comparison to Related Housing Price Measures
Census Bureau Constant Quality House Price Index (CQHPI). The FHFA HPI covers far more transactions than the Census survey. The CQHPI covers sales of new homes and homes for sale, based on a sample of about 14,000 transactions annually, gathered through monthly surveys. The quarterly HPI is based on more than 38 million repeat transaction pairs over 34 years. This gives a more accurate reflection of current property values than the Census index. The HPI also can be updated efficiently using data collected by Fannie Mae and Freddie Mac in the normal course of their business activity.

S&P/Case-Shiller Home Price Index. Both FHFA and C-S HPIs employ the same fundamental repeat-valuations approach, there are a number of data and methodology differences. Among the dissimilarities:
. The S&P/Case-Shiller indexes only use purchase prices in index calibration, while the all-transactions HPI also includes refinance appraisals. The FHFA purchase only series is restricted to purchase prices, as are the S&P/Case-Shiller indexes.
. FHFA valuation data are derived from conforming, conventional mortgages provided by Fannie Mae and Freddie Mac. The S&P/Case-Shiller indexes use information obtained from county assessor and recorder offices.
. The S&P/Case-Shiller indexes are value-weighted, meaning that price trends for more expensive homes have greater influence on estimated price changes than other homes. The FHFA index weights price trends equally for all properties.
. The geographic coverage of the indexes differs. The S&P/Case-Shiller National Home Price Index, for example, does not have valuation data from 13 states. The FHFA U.S. index is calculated using data from all states.