FHFA House Price Index: Conforming-Loan Prices

Key Takeaways

• The FHFA house price index uses repeat sales of homes financed by Fannie Mae and Freddie Mac.
• It excludes cash sales, jumbo loans, and FHA or VA mortgages, so coverage tilts to mid-priced homes.
• The purchase-only series uses sale prices, while the all-transactions series also adds refinance appraisals.
• It weights all homes equally, unlike the value-weighted Case-Shiller index.

What It Is

The FHFA house price index is published by the Federal Housing Finance Agency, the federal regulator of Fannie Mae and Freddie Mac. It applies a repeat-sales method, similar in spirit to Case-Shiller, but its data comes exclusively from mortgages bought or guaranteed by those two government-sponsored enterprises.

That source defines its scope. The index covers conforming loans, generally those under the annual conforming loan limit, and excludes cash transactions, jumbo loans, and FHA or VA mortgages. FHFA publishes a purchase-only series and a broader all-transactions series, and unlike Case-Shiller, its national index uses data from all states.

The Intuition

Like Case-Shiller, the FHFA index relies on repeat sales to isolate true price change. By comparing a home to its own prior sale, it filters out the distortion that comes when the mix of homes sold shifts from month to month. The two indexes share that core strength.

Where they part ways is coverage and weighting. Because the FHFA data only includes conforming-loan financed homes, it underrepresents the high end of the market, where buyers more often use jumbo loans or cash. It also weights every home equally rather than letting expensive homes dominate. The result is an index that leans toward mid-priced housing and gives a broader geographic read, which can diverge from Case-Shiller during periods when luxury and entry-level segments move differently.

How It Works

Two distinctions inside the FHFA family matter most:

Purchase-only index = repeat sales, purchase prices only
All-transactions index = purchase prices plus refinance appraisals
Equal weighting = each home counts the same regardless of price
Conforming-loan data = Fannie Mae and Freddie Mac mortgages only

The purchase-only index is the cleaner price gauge because it uses only actual sale prices. The all-transactions index adds appraisal values from refinances, which boosts sample size and geographic detail but introduces appraisal estimates rather than market prices. Analysts watching pure price movement usually prefer the purchase-only series.

Equal weighting is the key contrast with Case-Shiller. In the FHFA index, a price move on a starter home counts the same as a move on a mansion. In Case-Shiller, the mansion moves the index more. During a luxury-led rally, Case-Shiller can show faster gains than the FHFA index, and vice versa when entry-level homes lead.

Worked Example

Suppose both indexes are released for the same period. Case-Shiller shows national prices up 5% year over year, while the FHFA purchase-only index shows 3.5%:

Case-Shiller national:        +5.0% year over year
FHFA purchase-only:           +3.5% year over year
Gap:                          1.5 percentage points

The gap is not an error. It reflects methodology. Case-Shiller includes jumbo-financed luxury homes and weights expensive properties more heavily, so if the high end is leading the rally, it shows a faster gain. The FHFA index, limited to conforming loans and weighting all homes equally, captures more of the mid-market and so reports a cooler number.

The honest read is that home prices rose, but the high end rose faster than the middle. An investor who understood the methodology gap would not treat the two figures as contradictory. They measure different slices of the same market.

Common Mistakes

1. Treating it as the whole market. Conforming-loan data misses cash sales and jumbo-financed luxury homes, so the high end is underrepresented.

2. Mixing up the two series. The all-transactions index includes refinance appraisals. For pure price change, use the purchase-only series.

3. Expecting it to match Case-Shiller. Different data and different weighting produce different numbers. A gap is normal, not a flaw.

4. Ignoring the equal weighting. Every home counts the same. The index leans toward mid-priced housing trends.

5. Reading one month as a trend. Like all repeat-sales indexes, it is best read over several months or year over year.

Frequently Asked Questions

What is the FHFA house price index in simple terms? The FHFA house price index measures how US home prices change by comparing each home to its own prior sale, using only mortgages backed by Fannie Mae and Freddie Mac. That focus covers all states but leaves out cash and jumbo-financed homes.

How does the FHFA house price index affect investment decisions? It reveals the price trend in the conforming, mid-priced segment of housing, which matters for mortgage lenders and home equity. Comparing it to Case-Shiller helps investors see whether luxury or mid-market homes are leading price moves.

What is a real-world example of the FHFA house price index in action? When Case-Shiller shows prices up 5% but the FHFA purchase-only index shows 3.5%, the gap signals that high-end homes are rising faster than mid-priced ones. The two figures measure different slices, not conflicting facts.

How can investors use the FHFA house price index effectively? Use the purchase-only series for the cleanest price read and compare it with Case-Shiller to gauge which market segment is driving gains. Watch year-over-year change to filter out monthly noise.

How is the FHFA house price index different from the Case-Shiller index? The FHFA index uses only Fannie Mae and Freddie Mac conforming-loan data and weights all homes equally. Case-Shiller includes all arm's-length sales, including jumbo loans, and weights expensive homes more heavily.

Sources

1. Federal Housing Finance Agency. "House Price Index." https://www.fhfa.gov/data/hpi
2. Federal Housing Finance Agency. "House Price Index Frequently Asked Questions." https://www.fhfa.gov/faqs/hpi
3. Federal Reserve Bank of St. Louis. "The Differences between House Price Indexes." https://www.stlouisfed.org/on-the-economy/2015/january/the-differences-between-house-price-indexes
4. Federal Reserve Bank of St. Louis (FRED). "All-Transactions House Price Index for the United States (USSTHPI)." https://fred.stlouisfed.org/series/USSTHPI

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.