Over the past few years the health insurance industry has experienced a series of major mergers and acquisitions, further consolidating power into the hands of a few dominant companies — leaving Americans with fewer options.

In 2018, CVS Health ( CVS ) acquired Aetna. That same year Cigna ( CI ) bought Express Scripts and in 2023, Kaiser Permanente merged with Geisinger.

As of 2023, just four health insurers control a staggering 50% of the market , while six companies account for 30% of all healthcare spending in the United States.

While these mergers have boosted profits for these companies, they also, in some cases, raised premiums for consumers .

Here is a ranking of the largest health insurance companies by market share:

Centene, BS of California, BCBS of Michigan, BCBS of Florida — 2%

Centene ( CNC ), Blue Shield of California, Blue Cross Blue Shield (BCBS) of Michigan, and BCBS of Florida each hold 2% of the market.

Kaiser Permanente — 7%

Kaiser Permanente, which merged with Geisinger in 2023, has a market share of 7%

Health Care Service Corporation (HCSC) — 7%

Health Care Service Corporation, which generated $54 billion in revenue in 2023, controls 7% of the market.

Cigna — 11%

Cigna, which bought Express Scripts and in 2023, holds 11% of the market.

CVS Health (Aetna) — 12%

CVS Health, the parent company of Aetna, controls 12% of the market.

Elevance Health — 12%

Elevance Health ( ELV ), formerly known as Anthem, comes in second place in the ranking, holding 12% of the market.

UnitedHealth Group – 15%

UnitedHealth Group ( UNH ), the parent of United Healthcare, is the largest health insurance company in the U.S. with a market cap north of $500 billion. It serves more than 29 million Americans and controls 15% of the market.

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