FHFA House Price Index (HPI)

The FHFA House Price Index (HPI) is a repeat-sales measure of single-family house price changes published by the Federal Housing Finance Agency, built from repeat mortgage transactions on the same properties. It is reported at the national, census-division, state, metro-area, county, and ZIP-code levels, in purchase-only and all-transactions flavors. The data is free and public. Used in, for example, Heitz, Martin & Ufier, where a ZIP-level HPI serves as a time-varying collateral-value proxy in the moral-hazard analysis (Tables IV and V).

• Cost: free, public.
• API key: none required.
• Coverage: USA and census divisions from 1991 (monthly) and 1975 (quarterly); states, metros, counties; ZIP-code developmental indexes (annual). Purchase-only and all-transactions; seasonally adjusted and not.
• Home: https://www.fhfa.gov/data/hpi

Access

The master file appends every quarterly and monthly series into one CSV, no authentication:

# FHFA HPI master file: all geographies and flavors, no key
curl -sL -o hpi_master.csv \
  "https://www.fhfa.gov/hpi/download/monthly/hpi_master.csv"

The columns are hpi_type, hpi_flavor, frequency, level, place_name, place_id, yr, period, index_nsa, index_sa, rstderr, note. Filter on hpi_flavor (purchase-only, all-transactions, expanded-data), frequency (monthly, quarterly), and level (USA or Census Division, State, MSA, and so on) to pull the series you want.

The ZIP-code indexes are separate developmental files, and they are annual, not monthly or quarterly:

# Five-digit ZIP, all-transactions developmental index (annual, NSA)
curl -sL -o hpi_at_zip5.xlsx \
  "https://www.fhfa.gov/hpi/download/annual/hpi_at_zip5.xlsx"
# Three-digit ZIP variant:
curl -sL -o hpi_at_zip3.xlsx \
  "https://www.fhfa.gov/hpi/download/annual/hpi_at_zip3.xlsx"

Load in Python

import pandas as pd

df = pd.read_csv("hpi_master.csv")
# Purchase-only, monthly, national series:
us = df[(df.hpi_flavor == "purchase-only")
        & (df.frequency == "monthly")
        & (df.place_name == "United States")]
# index_nsa is the level; build returns within a (place_id, flavor, frequency).

Gotchas (the ones that bite pipelines)

• Purchase-only and all-transactions are different indexes. Purchase-only uses sales pairs from Fannie/Freddie purchase mortgages; all-transactions adds appraisal values from refinances and runs at lower frequency for finer geographies. They diverge, especially in stressed periods. Pick one flavor deliberately and do not splice them.
• The ZIP-code indexes are annual and developmental. FHFA publishes five-digit and three-digit ZIP indexes only at annual frequency, labelled developmental and not seasonally adjusted. There is no official monthly five-digit-ZIP FHFA series; a paper using “monthly ZIP-level HPI” has either interpolated the annual index or mapped a higher-frequency geography to ZIPs. Do not expect to download a monthly ZIP file from FHFA.
• NSA versus SA columns. The master file carries both index_nsa and index_sa; the seasonally adjusted column is populated only for some series. Choose the column to match your use and check it is non-empty for that series.
• It is an index, not a price level. Values are index numbers normalized to a base period (the purchase-only series is set to 100 at 1991Q1; other flavors and vintages use a different base), not dollar prices. Work in returns or ratios, and confirm the base before comparing across series.
• Repeat-sales coverage skews to conforming mortgages. The index is built from Fannie Mae and Freddie Mac loan data (and, for all-transactions, appraisals), so it underweights cash, jumbo, and non-conforming activity. This biases coverage in high-price and investor-heavy areas.
• Small geographies are noisy and revised. County and ZIP indexes rest on thin transaction counts; rstderr in the master file flags the standard error, and back-history is revised as new pairs arrive. Carry the standard error and re-pull rather than caching a small-area series indefinitely.

Geography levels (master file)

level value	Geography
USA or Census Division	National and the nine census divisions
State	50 states + DC
MSA	Metropolitan statistical areas
County	Counties (all-transactions, annual)
ZIP files (separate)	Three- and five-digit ZIP (annual developmental)

Citation

Cite the FHFA, the House Price Index, the flavor and geography, the URL, and the access date, for example: Federal Housing Finance Agency, House Price Index, purchase-only monthly series, retrieved from https://www.fhfa.gov/data/hpi, accessed YYYY-MM-DD. Record the flavor, frequency, geography level, and NSA/SA choice so the series is reproducible.