BlackRock's iShares Bitcoin Trust (IBIT) purchased $195.6 million worth of Bitcoin in a single session, according to on-chain data from Arkham, lifting the fund's total purchases over the past month to $1.57 billion.

One Fund Outpacing Its Entire Category

Flow data recorded a net inflow of $195.57 million for IBIT during the session, a total no other fund in the group matched that day. The broader group of US spot Bitcoin ETFs finished with a combined net inflow of $102.67 million — smaller than IBIT's haul alone.

The arithmetic is straightforward: if a single fund took in more than the entire category's net total, the other funds were collectively net sellers during the session. That degree of concentration means a single fund's creations can decide whether the category's headline number for the day is positive or negative.

The positive day also marked a reversal from the prior session, when spot Bitcoin ETFs posted an outflow of approximately $149 million before IBIT's buying turned the tally green again.

Zooming out to 30 days, the picture is steadier. The spot Bitcoin ETF category drew about $2.99 billion in net inflows over that stretch, and IBIT remained the top recipient. Set against that category figure, BlackRock's fund accounts for more than half of the month's net money on those numbers.

Bitcoin traded above $86,000 during the reported session.

How an ETF Actually Buys Bitcoin

IBIT works through authorized participants — large trading firms that create new ETF shares when investor demand rises and redeem them when demand falls. When investors buy more IBIT shares than are available, new shares are created in large blocks known as creation units. To keep each share backed by real Bitcoin on a 1:1 basis, the fund must acquire the matching amount of the asset. This creation and redemption process is a standard feature of the exchange-traded fund structure in the United States.

That mechanical link is why IBIT's flows are watched so closely: they translate brokerage-account demand directly into buying pressure on the underlying asset.

From Approval to Category Heavyweight

IBIT launched in January 2024, after the US Securities and Exchange Commission approved spot Bitcoin ETFs, debuting alongside a cohort of rival funds that now compete for the same investor demand. It is now the largest US spot Bitcoin ETF by assets under management, with AUM reaching $109.34 billion following the latest reporting.

The fund charges a management fee of 0.25%, and BlackRock — the world's largest asset manager — brings a distribution network that reaches advisers, wealth platforms, and institutions that smaller issuers struggle to access.

What It Means for the ETF Market

A growing share of institutional demand for Bitcoin appears to be flowing through regulated products like IBIT rather than direct ownership of the coins. The category swung from an outflow of approximately $149 million to an inflow of $102.67 million in consecutive sessions, and a month of $1.57 billion in IBIT buying points to a sustained trend rather than a one-day blip. At $109.34 billion in AUM, IBIT is already the benchmark against which the rest of the spot Bitcoin ETF market is measured.

The figures worth tracking in upcoming sessions are the daily flow reports themselves: whether IBIT continues to capture more than the category's net total, and whether the gap between its creations and its peers' redemptions widens or narrows.