Updated October 10, 2026. Rewritten with the verified history of the BlackRock-Coinbase relationship, including the 2024 custody amendment, current ETF figures and sources. Earlier versions described “contract amendments” without specifics and included figures that could not be verified.
BlackRock, the world’s largest asset manager, and Coinbase, the largest U.S. crypto exchange, are tied together in two ways: a 2022 deal that connected BlackRock’s institutional software to Coinbase, and Coinbase’s role holding the Bitcoin behind BlackRock’s giant Bitcoin ETF. Here is how the relationship developed and why it matters.
2022: Aladdin meets Coinbase Prime
In August 2022, months after the Terra collapse and before FTX failed, BlackRock and Coinbase announced a partnership linking BlackRock’s Aladdin investment platform, used by large institutions to manage portfolios and risk, with Coinbase Prime, Coinbase’s institutional trading and custody service. The goal was to let Aladdin clients who already used Coinbase Prime manage Bitcoin alongside their other holdings. Announcing it during a bear market signaled that BlackRock saw crypto as a long-term asset class.
2024: Coinbase becomes the ETF’s custodian
When BlackRock’s iShares Bitcoin Trust (IBIT) launched in January 2024, Coinbase Custody was chosen to hold its Bitcoin. IBIT grew faster than any ETF before it. By the end of March 2026 it held more than 800,000 BTC, worth about $55 billion at the time, and accounted for roughly 45% to 49% of all assets in U.S. spot Bitcoin ETFs.
The September 2024 amendment
In September 2024, rumors spread online that Coinbase was not actually holding all the Bitcoin backing the ETF. BlackRock amended its agreement with Coinbase so that Coinbase must move IBIT’s Bitcoin to a public blockchain address within 12 hours of a withdrawal request. Analysts, including Bloomberg’s Eric Balchunas, said the rumors lacked evidence, and Coinbase CEO Brian Armstrong said all ETF creations and redemptions in Coinbase custody settle on-chain. The amendment did not change the ETF’s structure, but it gave BlackRock a clear, fast way to take its coins out if it ever needed to.
2025–2026: diversifying custody
Concentration risk was a recurring concern: Coinbase custodies the Bitcoin for many U.S. spot ETFs. Since April 2025, Anchorage Digital has served as an additional custodian for IBIT, giving BlackRock a second option. Coinbase remains the primary custodian.
Why it matters
- Credibility: the world’s largest asset manager building on a crypto exchange’s infrastructure made it easier for other institutions to follow.
- Concentration: a large share of ETF Bitcoin sits with one custodian, which is why BlackRock tightened withdrawal terms and added a second custodian.
- Transparency: ETF investors rely on the custodian and auditors. Faster on-chain withdrawal rights and multiple custodians reduce, but do not remove, that trust.
Sources
- CryptoSlate: BlackRock amends Coinbase custody agreement to require 12-hour withdrawals (September 20, 2024)
- FinTech Weekly: BlackRock Q1 2026, IBIT holdings and custody (April 14, 2026)
- BlackRock: iShares Bitcoin Trust ETF product page
- Crypto Briefing: Spot Bitcoin ETF flows and assets (October 10, 2026)
This content is for informational and educational purposes only and is not financial or investment advice. Past performance is not indicative of future results.