BlackRock's spot bitcoin ETF has ranked as the most popular of the 11 new funds available on Robinhood in terms of volume, the company's chief brokerage officer Steve Quirk told The Block.

"The BlackRock one has been the one that's seen the most volume from our standpoint with Grayscale right behind it," he said in an interview.

"It’s basically our customers saying 'We want a low-cost avenue to have this be a component of our portfolio,'" he continued, adding that "Grayscale is a sale and it continues to be sale whereas the other ones continue to be largely buys."

Among Robinhood users who recently chose to buy spot bitcoin ETFs, a third of those customers did so after selling a portion of their existing portfolio, Quirk said.

"Of all the people that participated in trading these 11 …