BlackRock's IBIT leads $999M in US spot Bitcoin ETF inflows

Institutional money keeps finding its way into Bitcoin, and the numbers from September 21 make that point hard to argue with. US spot Bitcoin and Ether ETFs pulled in a combined $1.269 billion in net inflows on that single trading day, with BlackRock's iShares Bitcoin Trust leading the charge.IBIT alone attracted approximately $618 million, a figure that puts it comfortably ahead of the rest of the field. Fidelity's FBTC has consistently ranked as the second major beneficiary, but on this day BlackRock's product wasn't just winning the race, it was lapping it.Cumulative net inflows since the January 2024 launch have now reached approximately $55 billion to $55.8 billion. Total assets under management across US spot Bitcoin ETFs have surpassed $102.5 billion, with some estimates putting the figure closer to $105.6 billion by late September 2026.Bitcoin's price on September 21 was trading above $81,000, with intraday levels touching near $82,000. The week leading up to September 21 was not uniformly positive. Weekly Bitcoin ETF inflows had been modest, around $6.2 million, before the single-day rebound effectively reset the narrative.The $1.269 billion headline figure includes inflows across both Bitcoin and Ether spot ETFs. When spot Bitcoin ETFs launched in January 2024, Ether products were still waiting in the regulatory queue. Their eventual approval represented a second chapter in the institutionalization of crypto exposure, and the fact that they're contributing to record inflow days suggests that chapter is being read seriously.For BlackRock, IBIT's continued dominance in daily inflow rankings reinforces its position as the category leader. Fidelity's FBTC has been a consistent runner-up, and together these two products have captured the lion's share of net inflows on most trading days.With total AUM now north of $100 billion, these products are also starting to matter at a macro level. When IBIT buys Bitcoin on behalf of new inflows, that demand is real and immediate, hitting the open market the same day.