Warren Buffett has noticed a unique, never-before-seen phenomenon that’s emerged in the global economy: low inflation and negative interest rates.

“I don’t think there was any economist I’ve ever read that talked about negative interest rates for long periods of time.”

Buffett gave an interview with Yahoo Finance this week, extrapolating on what this means for investors and the global economy.

Per Yahoo:

“I think, now, there’s still $11 trillion, at least, of government debt around the world that’s at a negative rate,” Buffett told Yahoo Finance’s editor-in-chief, Andy Serwer. “So we’ve never seen it before.”

For example, the yield on Germany’s 10-year Bund is negative. That means investors have to pay to hold government debt.

“I don’t think there was any economist I’ve ever read that talked about negative interest rates for long periods of time,” he said.

Buffett added, referring to the economists John Maynard Keynes and Paul Samuelson, “If you go back and read Keynes or you read Samuelson, or you read any of them, they do not get into a negative rate environment.”

Another quirk in today’s economic landscape is the lack of inflation given ultra-low interest rates.

“And we’ve never seen, at least, the conventional wisdom on a sustained period of long and growing deficits, while the economy’s getting better. Extremely low interest rates, and really, very little inflation. So something different is happening, but something different happens all the time,” he said.

Still, Buffett, who is chairman and CEO of Berkshire Hathaway (BRK-A), doesn’t make decisions based on economic predictions.

“Charlie Munger — my partner and I (for) 54 years now — we’ve never made a decision based on an economic prediction,” Buffett added.

Buffett believes economic data doesn’t tell him how the economy will perform in the future.

“I like to get numbers — so I’m getting reports in weekly, in some businesses,” he said. “But that doesn’t tell me what the economy is going to do six months from now, or three months from now. It tells me what’s going on now with our businesses.”

When Buffett buys a business, he plans to hold it over the long-term, which he says decreases the efficacy of economic data points.

“If we buy a business [we’re going to] hold it forever — so we’re going to have good years, bad years, in between years — maybe disastrous years,” Buffett added. “And we care a lot about the price. We do not care about the next 12 months.”