Though it isn't clear how much the world's largest retailer would cough up for Jet, a personal familiar with the talks told Dow Jones that the website could be worth $3 billion, the organization reported Wednesday.
Wal-Mart declined to comment on the report; Jet.com did not immediately respond to CNBC's inquiry.
Wal-Mart shares edged up slightly, while Amazon declined following the news.
Wal-Mart CEO Doug McMillon said at the company's shareholder meeting in June that it would soon become more aggressive in growing its online business. Earlier this year, the company sold Yihaodian, its Chinese online marketplace, to JD.com. It likewise acquired a 5 percent stake in JD.
The retailer also completed the rollout of Walmart Pay earlier this summer, which allows shoppers to check out using their smartphones. Meanwhile, it's beefing up the amount of products sold on its website, and is looking to take on Amazon with its answer to Prime, called ShippingPass. That subscription service offers fewer perks than Amazon Prime, but costs just $49 a year. That compares with $99 annually for Prime.
All in, Wal-Mart plans to invest $1.1 billion into e-commerce this year.
Though Wal-Mart is the second-largest U.S. retailer in terms of online sales, its growth has recently stalled. During the first quarter, Wal-Mart's digital revenues rose 7 percent. That compared with a 17 percent jump in the prior-year period. Its results likewise fell well short of Amazon's first-quarter sales growth, of 32 percent.
Wal-Mart's digital sales account for an estimated 3 percent of its overall revenues, at roughly $13.6 billion, according to eMarketer.
Jet.com just celebrated its one-year anniversary. It has raised more than $500 million in funding in its quest to dethrone Amazon, according to CrunchBase. But its business model has shifted since its original launch. Though Jet initially charged a $50 membership fee, from which it said it would derive its profits, it eliminated that charge after only a few months.
Jet promises lower prices than its competitors, which it says is possible by bundling together items.