CVS has reportedly made an offer to acquire Aetna for $66 billion.

CVS Health is reportedly in talks to buy a major health insurer, Aetna, in a deal that would allow the pharmacy giant to expand into an entirely new arena of health care.

A successful deal could push millions of Aetna’s members toward CVS’ retail pharmacies, walk-in Minute Clinics, and services such as home visits for infusion drugs at a time when retail pharmacy companies are facing stiff competition.

It would also give Aetna the ability to move deeper into the lives of the 44.7 million people it serves and manage their health more efficiently. For example, the insurer might be able to get better insight into whether patients are taking their drugs by gaining access to data from CVS clinics and retail counters.

The Wall Street Journal reported Thursday that CVS Health had made a proposal to buy the health insurer for as much as $66 billion, which could make the deal the biggest merger of 2017.

Citing sources familiar with the matter, the WSJ said that the offer was more than $200 per share.

Analysts had been anticipating a deal of some kind. CVS Health has lost contracts in its retail pharmacy business recently, creating pressure on the company to find a way to grow, said Brian Tanquilut, a stock analyst at the investment firm Jefferies.

Meanwhile, health insurers have increasingly been moving toward bringing the negotiation of drug prices in-house, instead of outsourcing that work to companies called pharmacy benefit managers.

CVS Health may be best known for its retail pharmacy business, but it has been evolving. It works as a pharmacy benefit manager that negotiates drug prices on behalf of insurance companies. It also runs Minute Clinics, home infusion services and longterm care pharmacies that all mean it has a close relationship with patients - all of which could be valuable to Aetna.

Insurers have been seeking closer relationships with consumers as they try to manage health care costs, making sure that people seek care in the appropriate low-cost venues and manage health care conditions and adhere to taking medications rather than having expensive health care emergencies.