Key Highlights
BlackRock’s SIOP fund raised its iShares Bitcoin Trust holdings by 14% in Q3, according to a new SEC filing.
On-chain BTC and ETH transfers to BlackRock wallets were linked to ETF creation flows, not corporate crypto buying.
IBIT led U.S. Bitcoin ETF inflows as demand rose, while options activity and market interest continued to accelerate.
A new quarterly disclosure with the U.S. Securities and Exchange Commission (SEC) shows that BlackRock’s Strategic Income Opportunities Portfolio (SIOP) increased its holdings of the iShares Bitcoin Trust (IBIT) during the third quarter.
The fund reported 2.39 million shares of IBIT, worth about $155.8 million as of September 30. That’s up from 2.09 million shares at the end of June—a rise of roughly 14%.
SIOP is an unconstrained income fund that normally invests across bonds, mortgages, emerging-market debt, and cash equivalents. Because of its flexible mandate, it can also add exchange-traded funds (ETFs) when it sees value in doing so, which is why IBIT appears alongside its fixed-income assets.
Crypto transfers tied to ETF activity
Around the same time as the filing, blockchain data showed a large flow of cryptocurrency into wallets linked to BlackRock’s ETF operations. Over three days, the firm received about 4,044 Bitcoin (BTC) and 80,121 Ethereum (ETH) from Coinbase—roughly $589 million worth at current market prices.
BlackRock received 300 $BTC, worth $27.51M, and 16,629 $ETH, worth $50.64M, from #Coinbase, in the past 10 mins.In the past 3 days, they have received 4,044 $BTC worth $354M and 80,121 $ETH worth $235Mhttps://t.co/a9ele6V370 pic.twitter.com/kbZIxRMGdm— Onchain Lens (@OnchainLens) November 28, 2025
These transfers have sparked speculation online, but industry analysts stress that such movements come from ETF creation and redemption processes, not corporate buying. In a spot crypto ETF, authorized participants deliver Bitcoin or Ethereum to the issuer when new ETF shares are created.
BlackRock has not made any disclosure suggesting it is buying BTC or ETH for its own balance sheet. The pattern of transfers, including a single 300 BTC batch, matches normal ETF workflow.
IBIT gains as Bitcoin rises
The increased activity comes as Bitcoin climbed back above $91,000, helping IBIT trade about 2% higher in premarket action near $52.
Institutional ownership of IBIT has continued to grow and now sits at the highest level since the ETF launched, with more than 400 million shares held by institutions.
Options limit increase sought
Interest in the product is now spilling into the derivatives market, with the Nasdaq International Securities Exchange (ISE) seeking approval to lift the position limit on IBIT options to one million contracts—a sign that institutional traders are stepping up their use of options for hedging and market positioning.
Good catch.. new proposal to raise position limits on IBIT optons to 1 million contracts. They just raised the limit to 250,000 (from 25,000) in July. $IBIT is now the biggest bitcoin options market in the world by open interest. https://t.co/oxaUtP9Kyc— Eric Balchunas (@EricBalchunas) November 26, 2025
ETF flows shift toward BlackRock
Daily ETF flow data shows BlackRock maintaining momentum. On November 26, IBIT drew nearly $43 million in net inflows—the strongest among U.S. Bitcoin ETFs that day.
Fidelity’s Wise Origin Bitcoin Fund (FBTC), meanwhile, saw more than $30 million in outflows, and Grayscale’s Bitcoin Trust (GBTC) posted a small inflow of about $5 million.
Ethereum has also found fresh support, trading near $3,000 after a sharp intraday climb, which has contributed to steady ETF creation activity across ETH-linked products as well.
No evidence of direct Bitcoin buying
The latest SEC filing confirms that one of BlackRock’s own income funds has expanded its position in IBIT, while on-chain movements point to busy ETF operations rather than corporate accumulation of crypto.
Even with strong inflows and rising activity in both Bitcoin and Ethereum products, there is still no evidence that BlackRock itself is purchasing digital assets for its own books. For now, the growth appears driven entirely by investor demand for its ETFs.
Also Read: CoinShares Drops US Crypto ETF Plans Ahead of Nasdaq Listing