Aetna Inc. (/ˈɛtnə/; stylized as ætna) is an American managed health care company, which sells traditional and consumer directed health care insurance plans and related services, such as medical, pharmaceutical, dental, behavioral health, long-term care, and disability plans. Aetna is a member of the Fortune 500.

In June 2017, the company announced plans to move its headquarters to New York City in late 2018.

Aetna offers health care, dental, pharmacy, group life, disability, and long-term care insurance and employee benefits, primarily through employer-paid (fully or partly) insurance and benefit programs, and through Medicare. Membership numbers: (as of September 30, 2016)

Aetna has spent more than $2.0 million in 2009 on lobbying. The company spent $809,793 between January 2009 and the end of March 2009—up 41 percent from the same period in 2008. Aetna's campaign contributions include more than $110,000 to US Senator Joe Lieberman (ID-CT) in 2009. From 2005 through 2009, Aetna contributed $56,250 to Senator Max Baucus (D-MT), chairman of the Senate Finance Committee, making Aetna the senator's seventh highest contributor over that time period.

In the California Health Care Quality Report Card 2011 Edition, Aetna received 2 out of 4 stars in Meeting National Standards of Care and 1 out of 4 in Members Rate Their HMO. In the California Health Care Quality Report Card 2010 Edition, Aetna received 3 out of 4 stars in both Meeting National Standards of Care and How Members Rate Their HMO, for a rating of "Good" (out of "Poor, " "Fair, " "Good, " or "Excellent").

As of 2017 Aetna shares are mainly held by institutional investors (BlackRock, The Vanguard Group, State Street Corporation, T. Rowe Price, Capital Group Companies and others)

Aetna is the direct descendant of Aetna (Fire) Insurance Company, of Hartford, Connecticut. The name was meant to invoke Mount Etna, at the time Europe's most active volcano.

In June 2012, Aetna and Inova Health System announced a joint venture creating a new health insurance company, Innovation Health.

On July 3, 2015, Aetna announced that it planned to acquire Humana for US$37,000,000,000 in cash and stock, or US$230 a share. Aetna and Humana shareholders would have owned 74% and 26% of the new combined company. The acquisition was subject to United States government approval and was expected to close in late 2016.

On January 23, 2017, a federal judge blocked Aetna's merger with Humana, saying it would leave senior citizens with fewer options for Medicare coverage. On February 14, 2017, Aetna Inc. and Humana Inc. officially quashed a $34 billion merger agreement, after judges ruled against the merger for a second time.

On June 29, 2017, Aetna announced the company would be moving their main offices to New York City after being headquartered in Hartford since 1819. The moved will be completed in late 2018.

In 2000 Deadria Farmer-Paellmann, head of the nonprofit Restitution Study Group of Hoboken, New Jersey, disclosed that from approximately 1853 to approximately 1860 Aetna had issued life insurance policies to slaveowners covering the lives of their slaves.

Aetna acknowledged that concrete evidence exists for Aetna issuing coverage for the lives of slaves and released a public apology.

In 2002, Farmer-Paellmann brought suit against Aetna and two other companies in federal court asking for reparations for the descendants of slaves. The lawsuit said Aetna, CSX and Fleet were "unjustly enriched" by "a system that enslaved, tortured, starved and exploited human beings." It argued that African-Americans are still suffering the effects of 2½ centuries of enslavement followed by more than a century of institutionalized racism. The complaint blamed slavery for present-day disparities between blacks and whites in income, education, literacy, health, life expectancy and crime.

This suit was denied, and the denial largely upheld on appeal.

In 2006, Farmer-Paellmann announced a nationwide boycott of Aetna over the issue of reparations for its policies covering slaves. Aetna stated that its commitment to diversity in the workplace and its investment of over 36 million dollars in such areas as education, health, economic development, community partnerships, and minority-owned business initiatives in the African-American community are more effective at aiding descendants of slaves and African-Americans in general than making restitutions for Aetna's life insurance policies on slaves.