It has been three months since spot bitcoin ETFs began trading and BlackRock's fund appears to be on pace to usurp Grayscale's as the biggest of the crypto-based investment vehicles on offer.

According to Trackinsight data compiled by The Block Data Dashboard, as of Tuesday, BlackRock's IBIT fund had $18.2 billion in assets under management compared to Grayscale's $23.2 billion. 

As Grayscale's GBTC fund, which charges a higher fee than BlackRock's, has consistently shed capital since it began trading, BlackRock's ETF has been slowly narrowing the gap in terms of assets under management, or AUM. Grayscale's fund had about $23.4 billion in AUM two months ago compared to BlackRock's $4.4 billion, according to The Block Data Dashboard.

Grayscale's ETF started with nearly $30 …