The billionaire’s Berkshire Hathaway sold off about $900 million worth of Wal-Mart Stores stock in the last quarter, or about 90% of what he had left after years of paring his investment in the discount retailer. As recently as last summer, Buffett’s holdings in Walmart were worth $3 billion, and are now down to less than $100 million. The Oracle of Omaha first invested in the company in 2005.

While Walmart has not seen the same dramatic drops in stock market value in the last two years that have afflicted other retailers, like Macy’s (M), its stock is down 19% from a multi-year high in October 2014, reflecting market concerns about its prospects in competing with Amazon.com. Walmart has poured billions into its e-commerce efforts, bought Jet.com, and relaunched its marketplaces site allowing it to garner eight straight quarters of comparable sales growth in the United States, outperforming competitors like Target. (TGT) Those investments have also prompted Walmart to lower its profit forecasts.

Still, Amazon is running away with the e-commerce prize: by some estimates, the online retailer alone generated half of e-commerce’s growth over the 2016 holiday season. Walmart, as 55-year old behemoth, can only offer limited growth prospects.

Buffett himself seemed to take a dimmer view of traditional retail’s prospects at Berkshire’s annual meeting last year when he said of Amazon, “It is a big, big force and it has already disrupted plenty of people and it will disrupt more,” adding that many companies “have not figured the way to either participate in it, or to counter it.”

And in 2005, he said of Sears Holdings’ (SHLD) turnaround prospects that “Turning around a retailer that has been slipping for a long time would be very difficult. Can you think of an example of a retailer that was successfully turned around?”