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BlackRock overtakes exchanges in bitcoin custody and nears ethereum leadership
BlackRock is rapidly reshaping crypto custody dynamics in 2025 as its spot ETFs funnel institutional demand into regulated vehicles. iShares products for both Bitcoin and Ether have grown aggressively, shrinking liquid supply on exchanges and changing the balance of power between traditional custodians and crypto-native platforms like Coinbase and Binance.
Custody numbers: BTC and ETH positions
BlackRock's iShares Ethereum ETF now holds about 3.6 million ETH, less than 200,000 ETH behind Coinbase's reserves. That represents an addition of roughly 1.2 million ETH in under two months, signaling sustained institutional appetite for spot Ethereum exposure through ETFs. If current accumulation continues, iShares could pass Coinbase before year-end and narrow Binance's lead to roughly 1.1 million ETH.
On Bitcoin, BlackRock's IBIT has already collected roughly 745,357 BTC, surpassing Coinbase at 706,150 BTC and Binance at 584,557 BTC. These figures indicate BlackRock's emergence as the largest institutional custodian across both major assets, consolidating its influence over market structure and liquidity.
What this means for custody trends
The shift reflects a broader structural realignment: institutions are increasingly choosing regulated ETFs over direct exchange custody. This movement reduces available exchange balances, compresses sell-side liquidity, and can amplify the price impact of new buying. For markets that already prize scarcity, persistent ETF accumulation can contribute to tighter supply dynamics for both BTC and ETH.

Exchange inflows fall while ETF flows concentrate demand
On-chain data from CryptoQuant shows exchange inflows for Bitcoin have declined to their lowest 30-day moving average since May 2023, even as BTC trades near 111,000 USD. Both Coinbase and Binance report historically low deposits, a sign that retail and institutional sellers are not sending as much supply into exchanges as before. Lower inflows typically mean reduced selling pressure and a more constrained market supply.
Ether inflows reveal a similar pattern. The 30-day simple moving average of ETH deposits has dropped to around the April 10 low of 25 ETH, a time when ETH was trading near 1,700 USD. That metric is striking given Ether now trades close to 4,600 USD, suggesting holders are reluctant to liquidate and are exhibiting stronger conviction at higher price levels.
ETF flow details and short-term market impact
ETF flow data highlights where net demand is concentrated. Spot Ether ETFs recorded more than 1.5 billion USD in net inflows since Thursday in the referenced period, including one session that saw about 450 million USD of directed capital. Bitcoin ETFs experienced heavy outflows totaling 1.17 billion USD last week, but buying pressure returned with nearly 310 million USD in inflows across the most recent two days. These swings show capital rotating between products and underscore how ETF flows can quickly affect exchange balances and price dynamics.
Together, dwindling exchange deposits and accelerating ETF accumulation create a tightening supply backdrop for both Bitcoin and Ether. For traders, asset managers, and long-term investors, that combination points to more persistent bullish momentum into year-end unless a major change in flows or macro conditions occurs. Institutional adoption of spot ETFs, led by BlackRock, is clearly remapping custody and liquidity in the crypto ecosystem, with meaningful implications for price discovery, exchange behavior, and market structure.

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