BlackRock’s Strategic Income Opportunities (SIO) fund increased its holding in the iShares Bitcoin Trust (IBIT) by 14%, rising from 2,096,447 units in June to 2,397,423 units as of September 30, 2025, a position valued at roughly $155.8 million.
The internal reallocation reflects a fixed-income-oriented product shifting capital directly into spot-Bitcoin exposure and signals an institutional reassessment of crypto allocation strategies within traditional portfolio frameworks.
Institutional rotation highlights IBIT’s expanding role
The SIO shift materially changes the profile of an income-focused fund by allocating deeper exposure to IBIT. IBIT currently holds about 572,000 BTC and is positioned to approach 600,000 BTC, reinforcing capacity for institutional liquidity access. A notable operational deposit of approximately $390 million was routed through a prime custody channel, and IBIT’s fee structure is estimated to generate $191 million annually, supported by assets under management above $20 billion in 2025.
Institutional inflows surrounding IBIT have accelerated in parallel. D.E. Shaw increased its position by 345% and Tudor Investment expanded its stake by 82%, demonstrating strong multi-profile investment appetite. The trading environment evolved as well, with options open interest surpassing $38 billion and Nasdaq ISE proposing a jump in single-day contract limits from 250,000 to 1,000,000. IBIT’s global market presence broadened through its listing on the Australian Securities Exchange in November 2025.
The combination of internal allocation, large custody inflows and expanded derivatives rails produces three structural outcomes. Higher ETF custody balances increase on-chain deposit requirements, temporarily tightening spot liquidity availability. Additionally, enhanced options depth enables more efficient hedging and structured issuance, reducing transaction costs for scale participants. Finally, fee generation creates internal incentives for product growth, reflected in filings and launches tied to yield-oriented crypto vehicles.
Key metrics at a glance
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SIO units: 2,096,447 → 2,397,423 (Jun → Sep 2025)
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Allocation increase: 14%
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Position value: ≈ $155.8M
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IBIT custody: ≈ 572K BTC (nearing 600K BTC)
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Major deposit: $390M via prime custodian
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Estimated annual fees: $191M
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Reported AUM: > $20B
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Options open interest: > $38B
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Proposed options limit: 250K → 1M contracts
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Institutional moves: D.E. Shaw +345% | Tudor +82%
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IBIT ASX listing: Nov 2025
BlackRock’s 14% allocation increase effectively repurposes income-fund capital toward Bitcoin exposure, intensifying custody demand, derivatives liquidity and revenue dynamics across the IBIT ecosystem.