Ken Griffin, the CEO and founder of the Citadel hedge fund, has reiterated his negative stance on Bitcoin (BTC) in an interview with CNBC Wednesday, July 18.

Speaking at the Delivering Alpha Conference in New York, Griffin admitted that he “still scratch[es] [his] head" about Bitcoin, claiming that the younger generation should “do something more productive than invest in digital currencies.”

To prove his point of view, the billionaire pointed out that none of his clients have ever suggested investing in cryptocurrencies:

"I don’t have a single portfolio manager who has told me we should buy crypto, not a single portfolio manager.”

Griffin further declared that his company is having a “hard time” deciding whether it should be a liquidity provider for a product that he “[does not] believe in,” adding

“There’s no need for cryptocurrencies. They’re a solution in search of a problem.”

In late 2017, Citadel’s Griffin had made a similar statement about Bitcoin, comparing the top cryptocurrency with the “Dutch tulip bulb mania” in the 1600s and noting that “these bubbles tend to end in tears. And I worry about how this bubble might end."

Founded by Griffin in 1990, the Citadel hedge fund manages over $30 billion of assets. The global financial institution is one of the oldest hedge funds in the world, being only one of three percent of hedge funds that have been working for more than 20 years.

Others on Wall Street have embraced cryptocurrencies in their turn. Earlier this week, the world’s largest largest asset manager BlackRock announced it is setting up a working group to estimate the benefits of involvement in Bitcoin, a turn away from the company’s previous critical stance on cryptocurrency.

And last week, billionaire Steven Cohen’s Point72 Asset Management hedge fund reportedly invested in the Autonomous Partners crypto and blockchain-focused hedge fund.