Warren Buffett just fired a warning signal for the entire retail industry, and especially for Walmart.
In an interview with CNBC's Becky Quick on Monday, Buffett called retailing "too tough" and warned against investing in the industry.
He praised Amazon as a leader in ecommerce, and suggested that Walmart may never catch up to the online behemoth.
"That is a tough, tough, tough competitive force," Buffett said, referring to Amazon. "Now Walmart is pushing forward online themselves. They have got all kinds of strengths, but I just decided that I'd look for a little easier game."
"I think retailing is just too tough or me, just generally," Buffett said. "We bought a department store in 1966 and I got my head handed to me. I've been in various things in retailing... I bought Tesco over in the UK and got my head handed to me. Retailing is very tough and I think the online thing is hard to figure out."