Aetna vs UnitedHealthcare: what's the difference for employers?

Aetna and UnitedHealthcare are often the first two names on an employer’s renewal spreadsheet. Unlike some carriers, both still sell to small businesses as well as large employers, and both sell fully insured, level-funded and self-funded plans.

Ownership and size

Both carriers’ fully insured business has shrunk while self-funded business grows. UnitedHealthcare’s fully insured commercial membership fell from about 8.2 million at the end of 2025 to about 7.6 million by September 30, 2026, after it repriced those plans for 2026. Aetna’s fell from about 3.4 million to about 2.5 million in early 2026, largely reflecting its exit from the individual (ACA) exchanges in January.

Small businesses

UnitedHealthcare sells to small businesses, and its small business range includes UnitedHealthcare Level Funded and Surest alongside fully insured plans. Aetna’s 2025 annual report still lists small employers among the groups it insures, though Aetna left Connecticut’s fully insured small group market in 2024. Which of these each carrier will quote depends on your state and headcount.

Networks

UnitedHealthcare cites more than 1.8 million physicians and health care professionals and over 5,600 hospitals (its own analysis, June 30, 2026). Aetna’s 2025 annual report cites about 2.0 million participating providers. The two companies count differently, so the totals are not a like-for-like contest.

Both have national networks, but which local hospitals each has a contract with differs from city to city and can change at renewal.

Pharmacy ownership

Aetna is part of CVS Health, the company that also runs the CVS Caremark pharmacy benefit manager and CVS’s pharmacies and MinuteClinics. UnitedHealthcare sits in UnitedHealth Group alongside the Optum businesses, including Optum Rx.

Ratings

AM Best linked UnitedHealthcare’s downgrade to weaker operating results, driven largely by Medicare Advantage costs, and to governance and management changes. Both ratings sit in the same “Excellent” band.

What changed in 2025 and 2026

• Aetna left the individual (ACA) exchanges from January 2026, and its self-funded membership has grown while fully insured membership fell.
• UnitedHealthcare changed its group CEO in May 2025, repriced fully insured plans for 2026, and is replacing Oxford small group plans in Connecticut with UnitedHealthcare-branded plans from 2027.

Questions to ask a broker about these two carriers

1. Which of my employees’ doctors and nearest hospitals are in each carrier’s network?
2. Which funding types will each carrier offer a group our size in our state?
3. How have each carrier’s renewals run for similar groups here?
4. Are any hospital contract changes due in our area before our renewal date?
5. How would staff in other states be covered under each carrier’s network?

Our group health insurance quotes page explains what a broker will ask for, and the form below connects you with a licensed broker.

How we write these: every comparison uses the carriers' own published information, their parent companies' filings and independent surveys, each listed below with its date. We are not paid by, affiliated with or endorsed by any carrier, and we do not rank them, describe their plan benefits or recommend any plan. Carrier and product names are trademarks of their owners. Plans, networks and prices vary by state, county and group size: only a licensed broker or the insurer can say what is available to your business and explain its terms.