This tool was funded by Arnold Ventures, the Peterson Center on Healthcare, Gates Ventures, and The Washington Center for Equitable Growth.
© 2026 Health Care Affordability Lab at Yale. All rights reserved.
This data visualization tool allows users to explore how hospital mergers, closures, ownership changes, and rising market concentration are reshaping U.S. hospital markets.
Nearly 1 in 3 Health Care Dollars is Spent on Hospitals
The hospital sector accounts for the largest share (0%) of U.S. health care spending and approximately 6% of the U.S. Gross Domestic Product.
-- Health Spending, by Category
Source:
Since --, prices in the hospital sector have grown faster than prices in virtually any other sector of the U.S. economy.
Consumer Price Index, -- to --
Year -- = 100
Source:
Bureau of Labor Statistics
Hospital prices have increased 3x since --, outpacing the price growth of prescription drugs and physician services.
Market consolidation is one of the
primary drivers of hospital price increases
Over the past two decades, mergers and acquisitions have reshaped the U.S. hospital sector. Since 2000, more than 1,300 mergers have occurred among roughly 5,000 hospitals nationwide.
To identify communities exposed to meaningful reductions in competition in hospital markets, we highlight transactions that fall into what we refer to as Red Zone Mergers. These are mergers that, according to the Department of Justice and Federal Trade Commission guidelines, are likely to raise prices by lessening competition.
We measure market concentration using the Herfindahl–Hirschman Index (HHI) - a standard antitrust metric that ranges from 0 (many small competitors, highly competitive) to 10,000 (a monopoly). Red Zone Mergers are those that produce a post-merger HHI above 1,800 via an increase of more than 100 points. These thresholds align with federal antitrust benchmarks used to identify potentially anticompetitive mergers.
About one-third of all mergers since 2000 have met these Red Zone Merger criteria.
0 Cumulative Mergers
-- to 2025
Merger Location Time Lapse
--
Source:
Calculations made using a combination of data as described in Brot et al. (2024)
No Change
Did not participate in a transaction
Transacted
Participated in at least one non-Red Zone transaction
Red Zone Merger
Participated in at least one Red Zone transaction
Our research has shown that
Hospital mergers that lessen
competition raise prices
- The Price Ain't Right? Hospital Prices and Health Spending on the Privately InsuredFebruary 2019The Quarterly Journal of Economics
- Is There Too Little Antitrust Enforcement in the U.S. Hospital Sector?December 2024American Economic Review: Insights
Which Hospitals Face Competition?
Market concentration describes how much control a few hospital systems hold within a given area.
According to the Federal Trade Commission (FTC) and the Department of Justice (DOJ), markets with an HHI above 0 are considered highly concentrated—a level often associated with higher prices and fewer choices for consumers.
HHI Value & Market Concentration
Low
<1,000
Moderate
1,000 to <1,800
High
1,800 to <5,000
Higher
5,000 to <10,000
Monopoly
10,000
low levels of market concentration,
highly competitive
highest levels of market concentration,
little to no competition
In this visualization, each hospital’s market is defined as a 30-minute travel radius around that facility. Within this boundary, we calculate concentration based on:
- the number of hospitals in the area,
- their size (measured by bed count), and
- who owns those beds.
In practice, an HHI is the sum of the squares of the market shares of each competitor in the market. We define market shares as the ratio of a hospital’s beds to the total beds in its market.
This calculation method does not represent the legally defined “relevant antitrust market,” but serves as a consistent proxy for understanding local market concentration and ownership dynamics.
-Infinity Hospital Counts by Market Concentration
-- of hospitals have an HHI of more than 0. These markets are highly concentrated.
Source:
Calculations made using a combination of data as described in Brot et al. (2024)
Hospital Market HHI in the U.S., Infinity to -Infinity
Source:
Calculations made using a combination of data as described in Brot et al. (2024)
From Infinity to -Infinity, the average hospital HHI changed -- from -- to --.
This change reflects the growing consolidation among hospital systems.
Over Half of U.S. Hospitals Are in Markets That Experienced Significant Increases in Concentration
Not all mergers are problematic. We’ve categorized the impact of consolidation on all hospital markets over the time period into three groups:
Minimal Impact
<100 change in HHI
Significant Impact
>100 point increase in HHI
Persistent Monopoly Maintained
Minimal to zero competition
Change in Concentration by Mergers and Closures - 2000 to 2025
Source:
Calculations made using a combination of data as described in Brot et al. (2024)