Humana is in early-stage discussions with retail giant Walmart about a merger, according to a report by The Wall Street Journal, which cited unnamed sources.

Such a deal would fundamentally alter both the insurance and retail industries and comes on the heels of a string of announcements in which health insurance giants are merging with partners in related industries.

Shareholders of insurer Aetna and drugstore company CVS recently approved a $69 billion merger, while insurer Cigna and pharmacy benefits manager Express Scripts said just this month that they planned to merge in a $67 billion deal. The Humana/Walmart report surfaced just hours before voting begins on a merger involving Humana and Kindred Healthcare, which the parties had announced in December. Online retail giant Amazon, too, has said it plans to place a greater focus on health care.

Humana could not be reached immediately to comment on the latest report, which emphasized that the talks were preliminary and involve a possible partnership other than a merger. The parties already are working together on a Medicare prescription plan that provides customers with discounts on prescription drugs. Closer ties could allow the companies to steer more patients to Walmart stores for drug purchases.

An industry analyst had suggested in November that Humana was a takeover target of companies including Cigna and Walmart.

Humana at the time had taken steps including paying its executives millions of dollars in a “change of control” event.

Health care experts had told Insider shortly after the Humana/Kindred announcement, that such deals represented an escalation in the “arms race” between insurers and health care providers.

Before the latest wave of merger announcements, insurers had been merging with other insurers, and health care providers had been joining forces with other providers, as both sought to leverage their greater heft in reimbursement negotiations.

However, federal regulators last year intervened in some health insurance mergers, which stopped both the planned unions between Humana and Aetna as well as Cigna and Anthem on antitrust grounds.

Now, insurers are encroaching upon territory traditionally occupied by health care providers — and hospital systems are trying to expand to the point where they can bypass insurance companies altogether and negotiate directly with large employers.

When horizontal mergers — with companies in the same industry — are not available, vertical mergers — with partners in a related industry — are the “natural next step,” Daniel W. Sacks, assistant professor in the department of business economics and public policy at Indiana University’s Kelley School of Business, had told Insider.

CORRECTION: This post was updated to remove market reaction. Markets are closed today.