Thomas Daniels
In a defining adjustment to the crypto custody landscape of 2025, BlackRock has emerged as the preeminent institutional custodian for both Bitcoin and Ethereum, largely thanks to the expansion of its spot ETF holdings. This transformation underscores a shift toward regulated ETF structures over the traditional exchange custody model, driven by heightened institutional preference and regulatory clarity.
Bitcoin: BlackRock’s ETF Leads the Pack
BlackRock’s iShares Bitcoin Trust (IBIT) now holds approximately 781,160 BTC, eclipsing the reserves of both Coinbase, with about 703,110 BTC, and Binance, holding around 558,070 BTC. This milestone solidifies BlackRock as the largest known institutional manager of Bitcoin, second only to Satoshi Nakamoto in custody scale.
Ethereum: A Rapid Closing of the Gap
Meanwhile, BlackRock’s iShares Ethereum ETF (ETHA) holds 3.6 million ETH, positioning itself just 200,000 ETH behind Coinbase and within striking distance of Binance, which leads with 4.7 million ETH. Remarkably, ETHA has accrued 1.2 million ETH in under two months, spotlighting the accelerated pace of institutional accumulation.
Supply Contraction & Declining Exchange Inflows
On-chain data reveals a notable decline in BTC and ETH inflows to exchanges: the 30‑day moving average of BTC deposits has dropped to its lowest level since May 2023, coinciding with BTC trading near $111,000. In parallel, ETH inflows have dipped to spring lows, despite ETH trading well above those levels—strengthening the narrative of reduced sell-side pressure and heightened market conviction.
ETF Inflows Reinforce Market Dynamics
ETF inflows underscore institutional demand: ETH ETFs have drawn approximately $1.5 billion in net inflows since the previous Thursday, including a single-day surge of $450 million. Although Bitcoin ETFs recorded $1.17 billion in outflows last week, they have rebounded with $310 million in inflows over the past two days.
These data points illustrate how the dual forces of dwindling exchange deposits and ETF accumulation are constricting the circulating supply of both BTC and ETH—potentially laying the groundwork for sustained bullish momentum through year-end.
Structural Implications
BlackRock’s ascendancy reshapes the crypto custody framework. Where exchanges once held sway, institutional ETFs now play a commanding role, siphoning liquidity and centralizing custody under regulated vehicles. This shift could reduce volatility, attract further institutional inflows, and reinforce price support. Conversely, concentrated holdings under dominant institutions introduce counterparty risks and could influence price dynamics if unwinds occur.
