NEW YORK — Walmart is reportedly in talks to acquire health insurer Humana Inc. in a move to keep up with the consolidating health care marketplace and be competitive with Amazon.com.

The proposed deal, reported by The Wall Street Journal, would squarely position a Walmart-Humana combination against the CVS Health-Aetna union that is expected to be finalized this year.

Terms of a deal were uncertain, but Humana’s market value is about $37 billion. The purchase would be Walmart’s largest ever, eclipsing its $10.8 billion purchase of the U.K.’s Asda Group PLC in 1999. Walmart, the world’s biggest retailer, has a market value of about $260 billion.

Humana has 2.4 million Medicare Advantage members, and is one of the nation’s largest provider of such plans. In addition to the roughly 17% share of the Medicare Advantage market, a deal would offer Walmart a customer boon, alongside potential savings on the retailer’s health plan. It is currently the largest private employer in the country, with around 1.5 million U.S. employees.

While Humana pulled out of the Affordable Care Act’s exchanges after being hit with losses, its Medicare Advantage plans have recently been protected by both Republicans and Democrats. Walmart and Humana have already collaborated for over a decade on a popular Medicare drug plan that allows patients to get prescriptions at the discounter’s pharmacies with low co-pays. A joint company could establish a Medicare plan that could be sold in Walmart outlets and provide access to other low-cost health offerings at the chain.

Humana could employ Walmart’s analytic power to track consumers, and reduce the cost of care by moving some services into a lower-price environment. The insurer has already been adding health care services and is partnering with physician groups, and plans to purchase a stake in a home health and hospice operator.

Walmart’s purchasing power in the pharmaceutical market would be able to generate additional savings for Humana plan members. The insurer has its own pharmacy benefits manager, but it is smaller than the three PBMs that dominate the market: CVS Caremark; Express Scripts Holding Co., which has agreed to be bought by insurer Cigna Corp.; and the OptumRx business of United Health. Humana consequently has less leverage with drug makers.

For Cigna and Aetna, the decision to combine with other companies came after failed attempts to merge with fellow health insurers Anthem Inc. and Humana, respectively. The federal government had stepped in to block both deals, calling them anticompetitive and harmful to consumers.

CVS agreed to buy Aetna in December in a $69 billion deal aimed at allowing the drug store chain to capture more of the consumer health care spend. President and chief executive officer Larry Merlo said CVS is seeking nothing less than “to remake the consumer health care experience.” With Aetna’s data and CVS’ “human touch,” the combined entity “will create a health care platform built around individuals,” he said.

The combined company will be positioned as “America’s front door to quality health care, integrating more closely the work of doctors, pharmacists, other health care professionals” and companies “to create a platform that is easier to use and less ­expensive.”

The merger is characterized by the companies as a natural evolution for both as they seek to put the consumer at the center of health care delivery. CVS has steadily become an integrated health care company, and Aetna has moved beyond being a traditional insurer to focus more on consumer ­well-being.

While Walmart may now be pursuing the same strategy, it has far fewer stores than CVS. Without having stores that are as prevalent in neighborhoods as the drug chain’s, it may be less convenient for heath care services than CVS, said Piper Jaffray analyst Sarah James.