U.S. spot Bitcoin exchange-traded funds recorded nearly $1 billion in net inflows on September 21, marking one of the strongest single-day demand surges for the investment products in nearly a year.
According to data reported by The Block and CoinDesk, the ETFs attracted approximately $998.95 million during Monday’s session. It was the largest daily inflow since October 6, 2025, when the funds recorded more than $1.2 billion in inflows.
The renewed ETF demand arrived as Bitcoin rallied sharply, briefly moving above $87,000 before giving back part of its gains.
BlackRock Leads the Inflows
BlackRock’s iShares Bitcoin Trust, or IBIT, accounted for the largest share of Monday’s inflows.
IBIT attracted approximately $381.4 million, followed by the ARK 21Shares Bitcoin ETF with around $289.1 million and Fidelity’s FBTC with approximately $238.8 million.
Together, those three funds represented the overwhelming majority of Monday’s Bitcoin ETF inflows.
Other funds, including Bitwise’s BITB and Morgan Stanley’s Bitcoin product, also recorded positive flows during the session.
Bitcoin’s Rally Coincides With ETF Demand
The ETF flows came alongside a sharp move in Bitcoin’s price.
Bitcoin climbed from the low-$80,000 range and briefly crossed $87,000, reaching its highest level since January before retreating. The rally coincided with renewed risk appetite across financial markets and significant crypto short liquidations.
Presto Research associate Min Jung told The Block that there was no single clear catalyst for the move, pointing instead to a combination of renewed risk appetite, strong ETF demand and short covering after Bitcoin broke above key technical levels.
That distinction matters. Strong ETF inflows provide evidence of capital entering regulated Bitcoin investment products, but they do not by themselves guarantee that Bitcoin’s price will continue rising.
Ethereum ETFs Also See Strong Demand
The renewed appetite was not limited to Bitcoin.
U.S. spot Ether ETFs recorded approximately $269.98 million in net inflows on Monday, their largest single-day inflow since October 2025, according to SoSoValue data cited by The Block.
BlackRock’s Ethereum ETF, ETHA, was among the leading recipients, adding another sign that institutional demand was extending beyond Bitcoin.
Combined, Bitcoin and Ether spot ETFs attracted roughly $1.27 billion during the session.
A Strong Day, But Not Yet a Full-Year Trend
Despite Monday’s surge, the broader 2026 picture remains more complicated.
U.S. spot Bitcoin ETFs have still recorded a modest net outflow for the year, according to data reported by Cointelegraph, meaning the latest inflow represents a significant rebound rather than definitive evidence of uninterrupted institutional accumulation.
The next several trading sessions could therefore be important for determining whether Monday’s inflows represent a sustained change in demand or a particularly strong single-day response to Bitcoin’s price breakout.
For now, the headline number is difficult to ignore: nearly $1 billion entered U.S. spot Bitcoin ETFs in one trading session.
And with Bitcoin simultaneously pushing above $87,000, the latest move puts institutional flows back at the center of the crypto market conversation.
