In the first day of trading since the reports surfaced, Humana saw stocks climb 4.4 percent. Other insurance giants — UnitedHealth Group and Anthem — saw stocks rise 1.5 percent and 0.2 percent, respectively. Managed Medicaid insurer Centene was down 0.58 percent.
Walmart shares fell 3.8 percent after the news, CNBC reports.
Details of a potential Walmart-Humana deal remain vague. The two companies are discussing a variety of options, and it is not certain they will strike a deal. If they do reach an agreement, it would be Walmart's largest deal ever. Humana's current market value is about $37 billion, according to The Wall Street Journal.
Ayla Ellison contributed to this article.