Walmart is said to be considering an acquisition of the health insurer Humana.

Walmart is one of the largest retail pharmacies in the US, behind only Walgreens and CVS Health.

Humana has for years had a close relationship with Walmart, partnering on health plans and other initiatives. The conversations underway now also could lead to a closer relationship without a deal, Reuters reports.

But if the two were to combine, it would be the latest in a trend of integrating pharmacies and consumer businesses with health insurers.

Walmart buying an insurance company? It's not as crazy an idea as it might sound.

The insurance company in this case is Humana, which has held early-stage talks with Walmart focused primarily on new partnerships, according to multiple news reports.

A possible acquisition is also on the table, The Wall Street Journal reported.

You might think of Walmart as a giant retail business, but it's also one of the largest pharmacy chains in the US, behind only Walgreens and CVS. Walmart has long had a focus on affordable prescriptions as well, offering some generic medications for $4.

That's where the logic of buying an insurer starts to take shape.

One of Walmart's biggest pharmacy competitors, CVS, is already trying to do this, working on a $69 billion takeover of the insurance giant Aetna. The logic of a Humana deal would be pretty much the same for Walmart: It's a way to gain more leverage over drugmakers and medical-device companies as costs rise, the Bernstein analyst Lance Wilkes wrote in a note Friday.

The companies responsible for paying for healthcare expenses — like insurers — are feeling the effects of new procedures and innovative medications coming into the market with high price tags. To counter that, they've been consolidating, in part hoping that it will give them more of that leverage.

Walmart and Humana have for years been pairing up on different health initiatives — for example, through a cobranded Medicare drug plan and healthy-food credits. The relationship led analysts to speculate in December that a Walmart-Humana combination could be next.

Blurring the lines of what makes a healthcare company

In December, when CVS said it would buy Aetna, the idea of this kind of "vertical integration" — layering one part of the industry on top of another — was shocking.

But just a few months later, we heard of a second attempt when the health insurer Cigna agreed to acquire Express Scripts, the largest standalone pharmacy benefit manager, for $67 billion. The move combines a pharmaceutical middleman, responsible for negotiating discounts and rebates to prescription drugs, with a health insurer.

Both CVS and Humana have PBMs of their own.

Humana's approach to new combinations has focused on the majority of Medicare members it covers, the UBS senior healthcare analyst Jerome Brimeyer told Business Insider in January.

Last year, Humana purchased the home-healthcare operator Kindred Health with the help of private-equity firms. It was designed to help provide Humana customers with home-health options, a method of care that costs less staying in a hospital — and something that's more relevant to people who have insurance through Medicare.

As more companies look to cut costs and remove some of the pressure they're feeling in the health system, we may see more surprising combinations that challenge our definitions of healthcare companies.