Walmart Inc. WMT, +1.37% is in early-stage talks to acquire health insurance company Humana Inc. HUM, +0.48% The Wall Street Journal reported Thursday afternoon. Humana shares jumped 13% in after-hours trading following the report, while Walmart shares dropped less than 0.2%. The Journal, which cited anonymous sources, did not provide a potential price tag on a deal, but it noted that an acquisition would have to be the largest of all time for Walmart because Humana is currently worth about $37 billion. Walmart's largest acquisition to date was for $10.8 billion, the newspaper reported. The marriage of a retailer and health care is not as odd as it may have been in the past: Walmart rival Amazon.com Inc. AMZN, +1.11% has announced a partnership seeking to move into employee health care, and retailer CVS Health Corp. CVS, -0.80% has agreed to acquire Aetna Inc. AET, -0.25% Humana and Aetna had previously agreed to merge, but gave up on those plans amid antitrust concerns.