Surprise! Bitcoin is getting no love from two of the world’s wealthiest men.

“I would short if there was an easy way to do it,” Bill Gates said on Monday in an interview on CNBC. Gates said he had previously received some bitcoin as a birthday present, but sold those a few years later. “As an asset class, you’re not producing anything.”

Fellow billionaire and Gates pal Warren Buffett said the largest cryptocurrency is “probably rat poison squared” at Berkshire Hathaway’s annual shareholder meeting on Saturday.

The comments may be weighing on bitcoin’s price as the digital asset slumps 4.2% at 9.30am New York time to US$9 273, its first decline in four business days. Bitcoin climbed as much as 50% since slumping to near $6 500 four weeks ago, but the rally has lost steam before crossing $10 000.

Speculation that US regulators are meeting today to discuss whether ethereum, the second largest cryptocurrency, is a security, may also be limiting demand for cryptocurrencies. Ether is down almost 6%, and other large digital coins, like litecoin and Ripple’s XRP, are slumping too.

Buffett is echoing the words of his business partner Charles Munger, who in 2014 also compared bitcoin to rat poison. Gates is walking back some of his earlier optimism from four years ago, when he said bitcoin is “exciting”. — Reported by Camila Russo and Katherine Chiglinsky, (c) 2018 Bloomberg LP