Health insurer Aetna Inc. said Friday it would buy smaller rival Humana Inc. for about $37 billion in cash and stock, in the largest ever deal in the insurance industry.
The combination will push Aetna close to Anthem Inc.'s No.2 insurer spot by membership, and would nearly triple Aetna's Medicare Advantage business.
The deal will face antitrust scrutiny but if it goes through it would dwarf the previous largest insurance deal announced just this week, where Swiss property and casualty giant ACE Ltd announced it was buying Chubb Corp for $28 billion. It would also dwarf Anthem Inc.'s purchase of WellPoint in 2004 for $16.6 billion.
Analysts have said that M&A activity in the healthcare sector had been waiting for the outcome of last week's Obamacare ruling, which upheld key subsidies that underpin the reform and thus gave more certainty to healthcare insurers.
The bigger the insurer, the more power it has negotiating prices and improving its doctor networks.
Anthem has offered to buy Cigna Corp. to create the largest insurer in the country, toppling UnitedHealth Group Inc.
Media reports have also said UnitedHealth could be eyeing Cigna and Aetna. On Thursday, Centene Corp. said it would buy smaller rival Health Net Inc. for $6.3 billion.
Antitrust authorities, who were aggressive in their review of the failed deal between Comcast and Time Warner Cable, are expected to scrutinize how the combination of insurers will affect competition for each line of insurance: Medicare, Medicaid for the poor, individual insurance, commercial insurance for small and large businesses and the large employer business.
Aetna and Humana are in nine of the same states in Medicare Advantage. Combined, they would have market share of 88 percent in Kansas, 80 percent in West Virginia, 58 percent in Iowa and 51 percent in Missouri.
Wall Street analysts and some antitrust experts have said they expect the combination will be approved, although regulators may ask for some divestitures.
This story originally appeared on NBCNews.com