Aetna will acquire Humana for a combination of cash and stock valued at $37 billion, according to a joint news release from the two insurers.

According to data supplied by the companies (pdf), Aetna is the larger of the companies, with 23.67 million medical members to Humana’s 9.77 million. Aetna also has a larger dental insurance business, with 15.56 million members, compared with Humana’s 3.89 million.

In 2014, Aetna reported total revenue of $58 billion, while Humana reported revenue of $48.5 billion. Aetna reported a net income of $2.04 billion in 2014, compared with Humana’s $1.15 billion.

As Modern Healthcare notes, the deal must still survive antitrust review. The merger is presently expected to close in the second half of 2016.

If the merger is approved, the company would become the second largest managed care company in the United States, trailing only UnitedHealth Group.