The sell-off in Wal-Mart stock on Wednesday following an announcement that the company expects full-year revenue to be flat and profits to fall in fiscal year 2017 represents a "massive tipping point for e-commerce," Founders Fund partner Geoff Lewis said.
"People in the technology industry have been predicting that brick-and-mortar-based businesses like Wal-Mart are going to end up really struggling, and I think that that's actually now coming to the fore in this powerful way today," he told CNBC's "Squawk Alley."
"It always takes longer for these things to shift than people expect, but once they do shift, as Wal-Mart certainly has today, it happens very quickly."
Shares of Wal-Mart plunged as much as 9 percent on Wednesday, as the company shed more than $20 billion in market capitalization at the stock's low.
To be sure, Wal-Mart said 75 percent of its forecast reduction in earnings for 2017 will be due to its investment in wage increases. But it also said it would invest about $1.1 billion in fiscal 2017 to compete on e-commerce and digital platforms with rivals like Amazon.
Amazon surpassed Wal-Mart as the world's largest retailer by market cap in July.
"If you want somebody really to blame, you can blame Amazon, because Amazon is forcing the likes of Wal-Mart and Target to catch up, particularly with their e-commerce spend online, and as well, to make the stores more compelling," Stacey Widlitz, president of SW Retail Advisors, told "Squawk Alley."