BlackRock accounted for roughly 62% of the inflow

SoSoValue data put combined net inflows for the U.S. spot Bitcoin ETF complex at approximately $730.9 million for the day.

IBIT led with $453.96 million. ARK and 21Shares' ARKB added about $138 million, Fidelity's FBTC received roughly $74 million and Grayscale's two Bitcoin products brought in a combined $57 million.

VanEck's HODL and WisdomTree's BTCW were the notable exceptions, with about $20 million and $5 million in outflows respectively.

It was the industry's strongest single session since January 14, when daily inflows reached roughly $843.6 million.

The reversal from earlier in the week was enormous

September had not started with the same enthusiasm.

The funds recorded approximately $236 million in net outflows on September 1. IBIT alone accounted for around $201 million of those redemptions.

Two trading sessions later, BlackRock was driving the largest positive flow day in nearly eight months.

Spot ETF assets have crossed $103 billion

Total net assets across the U.S. spot Bitcoin funds ended the September 3 session at $103.34 billion, equivalent to slightly more than 6% of Bitcoin's total market capitalization at the time.

Cumulative net inflows since the products began launching in January 2024 reached $55.44 billion.

Those figures matter beyond a particularly strong Thursday. The ETF market has become a very large regulated interface between conventional brokerage accounts and Bitcoin exposure.

August had already been unusually strong

The September surge followed approximately $3.5 billion in net inflows during August, the best monthly result for the U.S. funds since September 2025.

Still, the September 3 session was unusually concentrated. Its $731 million intake was more than three times larger than any individual day during an 11-day inflow streak in late August.

Bitcoin briefly moved above $82,000

Bitcoin rallied alongside the flow data, trading above $81,000 late on September 3 and briefly moving beyond $82,000.

Crypto-linked equities participated as well. The Block recorded a 17.6% gain for Strategy, about 10% for Coinbase and 16.5% for Circle during the session.

Analysts initially pointed to a more favorable macro backdrop after Federal Reserve Governor Christopher Waller offered comments that markets interpreted as relatively dovish if inflation continued to cool.

Then the macro story changed again

The following day's U.S. employment report was substantially stronger than expected. Treasury yields and the dollar rose as markets increased expectations that monetary policy could remain tighter.

Bitcoin subsequently slipped back toward $79,500.

That sequence makes the ETF figure more interesting, not less. It also makes it harder to treat $731 million as automatic evidence that a new institutional bull cycle has begun.

IBIT can amplify both directions

BlackRock's scale is becoming visible in daily market-flow statistics.

The same ETF that accounted for roughly $201 million of the week's major redemption day subsequently attracted $454 million during its major inflow day.

Aggregate ETF figures can therefore swing dramatically when a relatively small number of very large allocations pass through IBIT.

The next several sessions matter more than one record

Public daily flow data shows how much capital entered or left each product. It does not identify every underlying buyer or reveal whether an allocation is tactical, a portfolio rebalance or a long-term institutional position.

What is clear is that regulated Bitcoin exposure attracted $3.5 billion during August and another $730.9 million in one of the first September sessions.

Whether that becomes a sustained September trend requires more than one extraordinary day.