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 [spot bitcoin ETFs], 33% of the people sold a portion of their portfolio — so they sold some equity — and then they bought these [ETFs]. So they basically made this a component of their portfolio."

Trading volume

While BlackRock’s new ETF is generating more volume on Robinhood, in the broader market, Grayscale has seen the most activity among spot bitcoin exchange-traded funds currently trading. A large portion of Grayscale’s volume has been generated by outflows, according to Bloomberg Intelligence.

The firm’s spot bitcoin ETF is a conversion of its flagship GBTC fund and charges a higher fee than some of its competitors. It's also much larger in terms of assets under management, and investors who had wanted to sell before the ETF conversion faced a hefty discount.  

Grayscale didn't immediately respond to a request for comment.

So far, more than 90% of all spot bitcoin ETF trading is going through the top three funds by volume, which are offered by Grayscale, BlackRock and Fidelity. Into their fifth day of trading, the cumulative trading total of all spot bitcoin ETFs was $12.7 billion as of 12:47 p.m. ET.

'Top 20' investment

Quirk, who is bullish about spot bitcoin ETFs, said he is pleased with how popular the new bitcoin-based instruments have been among Robinhood users.

"If we look at the overall volume in our world, these [ETFs] have worked their way up to the top 20" most popular investments on the platform," he said.

Last week, Robinhood announced it would list all 11 spot bitcoin ETFs on its trading platform.

"We believe crypto is the financial framework of the future and that increased access to bitcoin via ETFs is a good thing for the industry," Johann Kerbrat, general manager of Robinhood Crypto, said at the time.

Robinhood currently has 23 million users.