Goldman Sachs CEO Lloyd Blankfein is the latest banking executive to raise concerns over bitcoin, as the currency shot down below its previous high of $7,000 today.

Blankfein said “maybe bitcoin is kind of a bubble” in an interview with CNBC, stating that he was “not comfortable” with the currency.

Blankfein’s comments are in line with a growing skepticism in banking over the digital currency, joining the likes of JPMorgan Chase CEO Jamie Dimon, whose bitcoin feelings are well documented.

Bitcoin’s increasing valuation—the currency has jumped more than 600% this year—has been a cause of celebration for some in cryptocurrency, with some bitcoin enthusiasts dismissing Dimon and Blankfein’s bubble concerns as a mere lack of understanding.

Even Blankfein admitted part of the skepticism might be because of his long career, telling CNBC, “I’m kind of an old dog to be absorbing that kind of a new trick.”

Meanwhile, bitcoin lost about $1,000 of its value today, moving below $7,000. It is currently trading at $6,817.90 at 10:45 am ET.

Read more at Reuters, PYMNTs, and CNBC.