The FHFA produces three main HPI flavors – a purchase-only index, an all-transactions index, and an expanded-data index. CLLs are adjusted using FHFA’s national, nominal, seasonally adjusted, expanded-data index. The expanded-data FHFA HPI is based on an underlying sample of transactions that reflects the universe of what could be conforming loans, however, not all the loans have been purchased or securitized by Fannie Mae or Freddie Mac (the “Enterprises”). Data are combined between purchase-money mortgages from the Enterprises, FHA loans, and public records of sales transactions (with prices below the annual loan limit ceiling).
Prior to HERA, the Mortgage Interest Rate Survey had been used to adjust loan limits. After house prices fell in 2007, loan limits remained unchanged and FHFA began to consider alternative measures to the monthly survey. The expanded-data metric was created and input was gathered from the public. In 2015, FHFA addressed those comments and its plans to utilize the seasonally adjusted, expandeddata HPI for calculating changes to the CLLs. A “Notice of Establishment of Housing Price Index” is posted in the Federal Register at https://www.federalregister.gov/articles/2015/10/22/2015- 26778/notice-of-establishment-of-housing-price-index.
A major consideration had been the existing and well-known purchase-only index already published by FHFA but that index only utilizes Enterprise data. The expanded-data HPI employs the same basic methodology as the Enterprise specific purchase-only HPI but also incorporates additional historical transactions data. Specifically, the expanded-data indexes include transaction prices for homes with FHA-endorsed loans and homes whose transactions have been recorded at various county recorder offices through the country.
The addition of these two supplemental data sources to the Enterprise data provides for a better estimate of the overall change in the U.S. average home price than is available from the other indexes. General price changes and trends should be similar between all of the FHFA HPIs, however, the expanded-data HPI is best suited to capture movements for the segment of the housing market that has 3 a price range such that sales transactions could be financed with conforming loans because they fall below annual loan limits.