BlackRock’s IBIT Sees $1.26 Billion Block Sale in One of Bitcoin ETF Market’s Largest Single Transactions

A massive off-exchange trade has drawn scrutiny over who sold, why they sold at a steep discount, and what it signals for institutional bitcoin demand

A single block sale worth $1.26 billion in shares of BlackRock’s iShares Bitcoin Trust (IBIT) executed on May 26, 2026, has become one of the most closely analyzed transactions in the short history of spot bitcoin exchange-traded funds. The trade, executed at a notable discount to market price, points to a large institutional investor seeking a fast exit from bitcoin exposure rather than a routine arbitrage unwind — and it arrived at a moment when the broader bitcoin ETF market was already under significant strain.

The Trade in Detail

On May 26, 29.21 million IBIT shares changed hands off-exchange at $43.16 per share, while IBIT’s prevailing market price at the time stood at $44.17. That gap of $1.01 per share translated to a 2.3% discount — roughly $29.5 million in execution costs absorbed entirely by the seller.

The transaction was reported through the FINRA/Nasdaq Trade Reporting Facility (TRF) Carteret, a facility commonly used for privately negotiated, off-exchange block trades. By routing the sale through this channel rather than the open market, the seller avoided placing direct downward pressure on IBIT’s visible order book — a meaningful consideration when moving more than a billion dollars in a single transaction.

The sheer size of the concession is what drew the most attention. Sellers in block trades routinely accept modest discounts to ensure execution, but a $29.5 million haircut suggests the priority was speed and certainty rather than price optimization. In market terms, that kind of urgency tells a story.

BlackRock’s IBIT Sees $1.26 Billion Block Sale

NYDIG Rejects the Basis Trade Theory

In the days following the transaction, speculation circulated that the sale may have been tied to a bitcoin basis trade — a strategy in which an investor holds spot bitcoin or a spot bitcoin ETF while simultaneously shorting bitcoin futures contracts on the CME, seeking to profit from the price differential between the two markets.

Crypto investment research firm NYDIG analyzed the transaction and pushed back firmly against that explanation, offering two central arguments.

First, the economics do not hold up. A basis trade is built on capturing a relatively controlled spread between spot and futures prices. Accepting a 2.3% discount to exit the spot leg would consume a significant portion — or all — of any returns the strategy might have generated, making it a costly and irrational way to close the position.

Second, CME bitcoin futures volume showed no corresponding surge. NYDIG estimated that the IBIT block represented exposure equivalent to approximately 3,700 CME bitcoin futures contracts. Yet only 91 contracts traded during the specific minute the block was executed, with no unusual spike visible in the surrounding window.

“The size of the trade, the 2.3% execution discount, the absence of corresponding CME futures activity, and the limited universe of potential sellers collectively weigh against the view that the transaction represented a contemporaneous basis-trade unwind,” wrote Greg Cipolaro, NYDIG’s Global Head of Research.

Large BIT block trade

Who Sold? The Question Without a Public Answer

Identifying the seller has proven difficult through public data alone. NYDIG noted that the size of the block exceeded the disclosed IBIT holdings of every investor that appeared in recent 13F filings — the quarterly reports that institutional investors with over $100 million in assets are required to file with the U.S. Securities and Exchange Commission.

That means no single publicly disclosed IBIT holder, based on the most recent available filings, appears large enough to have been the sole source of the block. The seller could be an institution that had not yet filed updated disclosures, a foreign institutional investor not subject to 13F requirements, or an entity operating through intermediaries.

IBIT recorded approximately $720 million in net redemptions across May 26 and May 27, according to ETF flow data. However, NYDIG cautioned that aggregate ETF flow figures cannot be used to directly connect specific redemptions to the block transaction or to identify who initiated the sale.

A Weak Backdrop for Bitcoin ETFs

The trade did not happen in isolation. According to market data aggregator SoSoValue, U.S. spot bitcoin ETFs recorded net outflows on every single trading day from May 15 through May 29, 2025. Total assets across the category fell from approximately $107.75 billion on May 14 to $94.17 billion by May 29 — a drop of more than $13 billion in two weeks.

Bitcoin itself has declined roughly 16% in 2026, while equities, commodities, and other asset classes have attracted stronger capital flows, reflecting a broader reallocation away from digital assets among some institutional investors.

Against that backdrop, the IBIT block sale reinforces a broader pattern: institutional holders of spot bitcoin ETFs have been reducing exposure, and at least one large holder chose to accept a near-$30 million execution cost to do so quickly.

Bitcoin ETF Flow (Source: Fairside Investors)

What It Means for the Bitcoin ETF Market

IBIT remains the world’s largest spot bitcoin ETF by assets under management. The block sale does not represent a collapse in institutional interest, but it does illustrate how quickly liquidity preferences can shift when market direction weakens.

For investors and market watchers, the clearest signal from the trade is not the identity of the seller — which remains unknown — but the urgency embedded in the pricing. When a holder of more than $1 billion in a liquid ETF chooses to sell at a 2.3% discount rather than work the order over time, it reflects either a hard deadline, a risk-management constraint, or a conviction that waiting carries more risk than losing $29.5 million on execution.

NYDIG’s conclusion is measured but pointed: this was most likely a large investor choosing certainty over price during a period of sustained pressure on bitcoin-linked products.