Citadel's Ken Griffin is not a fan of digital currencies and bitcoin.

"I don’t have a single portfolio manager [of mine] who has told me we should buy crypto, not a single portfolio manager," he said at the Delivering Alpha Conference in New York on Wednesday. "I have a hard time finding myself wanting to be in the position of being a liquidity provider to a product that I don’t believe in."

The investor said he wishes the younger generation would focus on more productive activities than investing in digital currencies.

"I still scratch my head" about bitcoin, he added.

Griffin founded Citadel in 1990. The investor has a net worth of $9 billion, according to Forbes. His hedge fund firm now manages more than $30 billion in assets. Also in its role as a market maker, 1 out of every 5 U.S. stocks trade through Citadel Securities on a daily basis, Griffin confirmed.

The firm’s multistrategy fund, known as Wellington, was up 1.52 percent in June and 8.79 percent during the first half of the year.