Investing icon Warren Buffett said he would consider taking money out of banks, especially if negative interest rates result in customers being charged to park their money in accounts.

"There could be a point where you'd really want to start withdrawing currency," Buffett told CNBC Monday.

"If currency in a bank is worth less than currency in your hands ... that could produce something in the way of behavior," he said. "It's a different world. If you have a lot of money in euros, as we do ... you're better off putting it under your mattress than in a bank."

Buffett says the Federal Reserve and other policymakers are generally doing a good job, but it's difficult to predict all the effects of interest rates remaining low for this long.

Buffett said that no one can predict the effects of prolonged low rates because it has never happened before, but the U.S. economy has substantially recovered from the depths of the recession in 2008.

While he confessed that global central bank strategies amount to  a "fascinating movie to watch," Buffett said he doesn’t try to wager on central bank moves. Many global central banks have kept interest rates low, with many pondering negative rates.

"We have close to $60 billion that's out invested at about a quarter of percent or less," the Berkshire chairman and CEO said. "One point on $60 billion is $600 million a year. If we were getting 3 or 4 percent on that money, that's a couple billion to us. You notice it."

Buffett appeared on CNBC Monday after spending more than five hours answering questions at Berkshire Hathaway's annual meeting on Saturday. Buffett estimates roughly 40,000 people attended the shareholders meeting. This year's addition of a webcast of the meeting didn't result in a significant drop in attendance from last year's crowd that was close to 45,000.

In a wide-ranging, three-hour live interview:
 

• Buffett says he would be willing to sell Berkshire Hathaway's big investments in American Express, Coca-Cola and other companies if he found a significantly better option, but he still believes in those companies. Buffett's Berkshire Hathaway Inc. has held major stakes in American Express and Coca-Cola for decades, so the company would face a significant tax bill on the gains if he did ever sell those investments. Buffett says the tax implications are a factor in his decisions.
• Buffett says he likes owning roughly 15 percent of American Express' stock even though competitors are trying to develop a better way to process payments. Berkshire owns about a 9 percent stake in Coca-Cola Co.
• Buffett says Valeant Pharmaceuticals' practices were flawed, so he declined to invest Berkshire Hathaway's money in the company. Buffett says some Valeant shareholders urged him to look at investing in Valeant in recent years, but he decided not to after examining the company. Valeant is dealing with intense scrutiny of its business practices, a huge drop in stock price and insurers are demanding discounts from its drug prices. Current and former Valeant officials were grilled by Congress last week over the company's strategy of buying up older medicines with limited competition and then jacking up their prices many times above prior levels.
• Buffett says choosing the next president will be important for the world, but it won't derail the U.S. economy. Buffett supports Democrat Hillary Clinton, but he says choosing the wrong president won't damage the economy. He says some of the country's past presidents haven't been great, but business has thrived over time.