BlackRock's iShares Bitcoin Trust shed $527.84 million on Wednesday, the second-largest single-day net outflow since the fund launched in January 2024, per SoSoValue data.

The figure missed the record by a razor-thin margin. IBIT's biggest outflow on record remains the $528.3 million pulled on Jan. 30, which Wednesday's draw came within about $500,000 of matching. The fund holds roughly $59 billion in assets and accounts for close to 4% of bitcoin's total supply, making it the largest single vehicle for institutional bitcoin exposure.

The outflow was part of a broader exodus. The 11 U.S.-listed spot bitcoin ETFs lost a combined $733.43 million on Wednesday, with Fidelity's FBTC shedding $60.30 million and Grayscale's GBTC losing $104.76 million alongside the IBIT draw. The complex has now posted outflows for several consecutive sessions, with more than $2 billion withdrawn over the past two weeks.

The selling landed on the same day bitcoin broke below $73,000. The cryptocurrency traded at $72,978 in Asian hours Thursday, down 3.4% over 24 hours, after U.S. airstrikes on an Iranian military site near the Strait of Hormuz reignited a conflict markets had started to price out. The ETF outflows and the price drop fed each other, with redemptions forcing BlackRock and other issuers to sell the underlying bitcoin to settle investor exits.

The IBIT draw came a day after a separate eye-catching move in the fund. On Tuesday, a single investor sold $1.29 billion of IBIT shares in one dark-pool block trade, as CoinDesk reported.

A dark-pool trade is a privately negotiated transaction that lets large players move size without tipping off the broader market. That block sale was not the same as a net outflow, since buyers can step in to absorb the volume, and IBIT's actual net redemptions on Tuesday came to $192.44 million. But the two events together point to institutional players trimming bitcoin exposure as the macro backdrop turned.

The flow data has been pointing this way for weeks. ETF accumulation across the year had already thinned to a net of around 4,500 BTC, and May flipped from the steady buying of March and April into distribution, as reported on Wednesday. Bitcoin has dropped from above $82,000 on May 6 to under $73,000 now, and the ETF channel that drove the 2025 rally has spent the month pulling money the other way.

Whether the outflows mark tactical de-risking around the Hormuz headlines or a deeper institutional pullback depends on what happens once the Middle East situation stabilizes. IBIT has gone through extended outflow streaks before during this cycle without a permanent reversal, with money returning each time the macro picture cleared.