CVS Health (NYSE:CVS) has announced it has reached a deal to purchase Aetna (NYSE:AET) for about $69 billion. Under the terms of the deal, CVS will pay about $207 a share for the insurer. Roughly $145 a share of that would be in cash, with the remainder in newly issued CVS stock. Aetna stockholders will own about 22 percent of the combined company, while CVS shareholders will own the remainder.

The transaction will be one of the largest of the year. Including the assumption of Aetna’s debt, the total value of the transaction is about $77 billion. The deal is expected to close in the second half of next year, subject to approval by shareholders of both companies as well as regulators.

Some think that the deal will receive antitrust approval because the combination of a drugstore company and an insurer is considered less problematic than a merger of two players in the same business. Deals combining companies in two different industries have traditionally met little opposition in Washington. However, both companies are significant players in offering prescription drug plans to Medicare beneficiaries.

The deal has the potential to reshape the nation’s health care industry. Together, CVS and Aetna would provide most of the basic health services that people regularly use. Aetna is one of the biggest health insurers in the United States. CVS operates a chain of pharmacies and retail clinics.

In their announcement, the two companies announced a plan to transform CVS’s 10,000 pharmacy and clinic locations into inexpensive community-based sites of care. The community-based clinics will be capable of delivering care with the technology and health information available from both parties. CVS Health’s chief executive Larry J. Merlo said the plan is “creating a new front door to health care in America.”

The deal could result in lower costs to both CVS and Aetna. Mark T. Bertolini, Aetna’s chief executive, said that the company can provide people with a better way of accessing medical care by using CVS’s locations. Mr. Merlo said, “We know we can make health care more affordable and less expensive.”

Critics have expressed concerns that the deal would mean customers could find their choices limited sharply. The concern stems from the possibility that those with Aetna insurance may be forced to go to CVS for much of their care. Mr. Bertolini asserted that the companies would not raise prices for consumers.