Major health insurance stocks rose across the board Monday, the first day of trading since reports revealed Walmart has discussed an acquisition of Humana.
Shares of Humana closed up 4.4 percent. Shares of Anthem, UnitedHealth and Medicaid-provider Centene closed up 0.2 percent, 1.5 percent and down 0.58 percent, respectively, while shares of Walmart fell 3.8 percent.
Though discussions remain in early stages, sources confirmed to CNBC that Walmart is interested in strengthening its existing relationship with Humana amid a rush of deal speculation in the industry.
People familiar with the matter cautioned that details of the deal remained vague and that it's possible one may never materialize.
"Under its current alliance with Walmart (which began in 2005), Humana stations representatives in Wal-Mart stores, Sam's Club locations and Neighborhood Markets across the country who seek to enroll Medicare-eligible individuals," said Credit Suisse analyst A.J. Rice. "By way of background, Humana operates its own pharmacy benefit manager that services its own health plan offerings. The PBM also has a state of the art mail order facility that has a strong specialty capability."
Still, any such move by Walmart heightens attention on the remaining health insurance companies as potential partners for large retailers or other big companies in their efforts to expand into other sectors.
CVS Health announced a $69 billion deal to buy insurer in December. That would combine CVS' pharmacies and pharmacy benefit manager platform with Aetna's insurance business.
Online retail behemoth Amazon, J.P. Morgan Chase and Berkshire Hathaway also have teamed up to tackle rising employee health-care costs. CNBC also has reported that Amazon has participated in exploratory talks with generic drugmakers.
— CNBC's Lauren Hirsch contributed to this report.