What Is the S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index?

The S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index measures the change in the value of the U.S. residential housing market by tracking the purchase prices of single-family homes. The index is compiled and published monthly.

The national index is widely viewed as a barometer of the U.S. housing market and the broader economy. In media reports, it is often called simply the Case-Shiller Home Price Index.

The national index is one of three related Case-Shiller indices. The others are composite indices of housing prices in 10 cities and 20 cities.

Key Takeaways

  • The S&P CoreLogic Case-Shiller National Home Price Index measures the changes in the sale prices of single-family homes across the U.S.
  • It does this by tracking the purchase prices and resale prices of homes that have undergone a minimum of two arm's-length transactions.
  • The index was developed in the 1980s by Allan Weiss, Karl Case, and Robert Shiller and has gone on to become a widely used and respected barometer of the U.S. housing market and the broader economy.

Understanding the S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index

The Case-Shiller Index was developed in the 1980s by three economists: Allan Weiss, Karl Case, and Robert Shiller. Since then, it has gone on to become a widely used and respected barometer of the U.S. housing market and the broader economy.

The housing market and the overall economy are interlocked in many ways. When real estate prices go up, homeowners often feel more secure and loosen their purse strings. Developers grow confident and show it by investing more in building new houses. This overall activity boosts gross domestic product (GDP).

Most American houses are owner-occupied, so looking at housing price indexes can provide a good idea of how much money is circulating in the economy. This means that the S&P CoreLogic Case-Shiller National Home Price Index, one of the most well-renowned measures of house valuations in the U.S., is closely monitored by economists and investors.

What the Index Tells You

The S&P CoreLogic Case-Shiller Indices do not cover everything. The big exceptions include newly constructed houses, condominiums, and co-ops. 

There is a two-month time lag in the data reported, so a report issued in May, for example, would cover home sales through March.

All prices are compared to their prices one year before. Beyond these headline numbers, those who are interested can see the numbers in comparison to one month ago, three months ago, and year-to-date. Annualized changes over three years, five years, and 10 years also are published by S&P Global.

The Case-Shiller indices are perhaps the best-known trackers of residential property prices. However, there are several alternatives that investors can use to track real estate valuation fluctuations.

They include the Federal Housing Finance Agency's (FHFA) Housing Price Index (HPI), First American CoreLogic's LoanPerformance Home Price Index, and the IAS360 House Price Index. Each index differs in terms of the criteria it uses.

According to Trading Economics, the Case Shiller Home Price Index averaged 169.87 points from 2000 until 2021. It reached an all-time high of 257.10 points in April 2021 and a record low of 100 points in January 2000.

The 3 S&P CoreLogic Case-Shiller National Home Price Indices

The S&P CoreLogic Case-Shiller National Home Price Index has two offshoots, published separately, that focus on home prices in major U.S. cities.

  • The national home price index covers nine major census divisions. It is calculated quarterly and published on the last Tuesday of February, May, August, and November.
  • The 10-city composite index, covering Boston, Chicago, Denver, Las Vegas, Los Angeles, Miami, New York, San Diego, San Francisco, and Washington, DC. It is published on the last Tuesday of each month at 9 a.m. Eastern Standard Time (EST).
  • The 20-city composite index, including all of the above cities plus Atlanta, Charlotte, Cleveland, Dallas, Detroit, Minneapolis, Phoenix, Portland (Oregon), Seattle, and Tampa. It also is published on the last Tuesday of each month at 9 a.m. Eastern Standard Time (EST).

S&P CoreLogic Case-Shiller National Home Price Index Methodology

According to S&P CoreLogic, the indices are compiled using the following methodology:

  • Repeat Sales Method: Each index measures changes in the prices of single-family, detached residences using the repeat sales pricing technique.
  • Index Approach: Indexes are based on observed changes in home prices and are designed to measure increases or decreases in the market value of the residential real estate in 20 defined metropolitan statistical areas (MSAs) and three price tiers—low, middle, and high.
  • Creation of Sales Pairs: The movement in the price of single-family homes is measured by collecting data on actual sale prices. When a home is resold, the new sale price is matched to its first sale price. These two data points are called a "sale pair" and the difference in the sale pair is measured and recorded. Sales pairs yield the price change for the same houses, keeping the quality and size of each house constant.
  • The Weighting of Sales Pairs: The indexes are value-weighted and designed to control for the quality change in the homes being measured. Sales pairs are assigned weights to account for price fluctuations that can be attributed to factors such as extensive remodeling, an addition, or extreme neglect. Time intervals between sales are also considered.
  • Three-Month Moving Average: Indexes are calculated monthly using a three-month moving average algorithm. Home sales pairs are accumulated in rolling three-month periods.