A $528 million exodus from BlackRock’s bitcoin ETF marked the second-largest one-day outflow the fund has ever seen.

BlackRock’s iShares Bitcoin Trust (IBIT) posted its second-largest daily net outflow on Wednesday, narrowly missing its January record, as geopolitical tensions linked to Iran prompted institutional investors to scale back bitcoin exposure.

The fund recorded $527.84 million in net redemptions, according to SoSoValue, just shy of the $528.3 million withdrawn on Jan. 30 — its largest outflow to date. Despite the pullback, IBIT remains the leading institutional bitcoin vehicle, holding about $59 billion in assets and accounting for roughly 4% of total bitcoin supply.

The move was part of a broader wave of selling across U.S. spot bitcoin exchange-traded funds. The 11 listed ETFs collectively saw $733.43 million exit on the day. Fidelity’s FBTC shed $60.30 million, while Grayscale’s GBTC posted $104.76 million in outflows, adding to IBIT’s losses. The group has now recorded multiple consecutive sessions of net redemptions, with more than $2 billion withdrawn over the past two weeks.

The outflows coincided with renewed downside in bitcoin’s price. The asset slipped below $73,000 on Wednesday and was trading at $72,978 during Asian hours on Thursday, down 3.4% over the previous 24 hours. The decline followed U.S. airstrikes on an Iranian military target near the Strait of Hormuz, reigniting geopolitical risks that markets had recently begun to discount.

ETF outflows and price declines appeared to reinforce one another, as redemptions required issuers to sell underlying bitcoin to meet investor withdrawals.

The heavy outflow followed a notable transaction a day earlier, when a single investor sold $1.29 billion worth of IBIT shares in a dark-pool block trade. Such trades allow large participants to execute sizable transactions away from public markets, minimizing immediate price impact.

While the block trade did not directly equate to net outflows — as counterparties can absorb the shares — IBIT still registered $192.44 million in net redemptions on Tuesday. Together, the activity suggests institutions have been actively reducing bitcoin exposure as macro conditions shift.

Fund flow trends had already been weakening. Net ETF accumulation for the year has slowed to around 4,500 BTC, while May marked a shift from the steady inflows seen in March and April to consistent outflows. Over the same period, bitcoin has fallen from above $82,000 on May 6 to below $73,000, with the ETF channel that previously supported the rally now contributing to selling pressure.

Whether the recent outflows represent short-term risk reduction or a more sustained institutional retreat will depend on how geopolitical tensions evolve. Previous cycles have shown that IBIT can endure extended periods of outflows without signaling a lasting reversal, with inflows typically resuming once macro uncertainty subsides.