BlackRock’s iShares Bitcoin Trust has overtaken Grayscale’s GBTC to become the world’s largest spot Bitcoin ETF by assets under management.
Recent data from Arkham Intelligence shows BlackRock acquired $623.5M in Bitcoin in one week, while Grayscale sold about $62.3M, reflecting a 10-to-1 accumulation ratio.
Grayscale sold a total of $62.3M of BTC since Monday.
However, BlackRock net purchased over 10x that amount, buying $623.5M of BTC so far this week.
BlackRock now holds over $64.85B of Bitcoin, 3.87% of the total BTC supply.
— Arkham (@arkham) May 8, 2026
BlackRock now holds over $64.85Bn in Bitcoin, controlling 3.87% of the total supply. This shift in Bitcoin ETF flows has been ongoing since spot ETFs received SEC approval in January 2024.
IBIT, launched on January 9, 2024, quickly reached $20Bn in AUM, setting a record across all asset classes. With strong inflows of $2.44Bn in April 2026, IBIT has surpassed GBTC, marking a significant trend in institutional adoption.
(SOURCE: TradingView)
Bitcoin ETF News: How IBIT Displaced GBTC as the Market’s Benchmark Bitcoin Fund
The mechanics of this overtake are rooted in a single structural asymmetry: cost. BlackRock IBIT charges 0.20% annually; Grayscale GBTC charges 1.5% – a 7.5x fee differential that became untenable for institutional allocators once a regulated, liquid, lower-cost alternative existed.
Grayscale’s Bitcoin holdings peaked at 619,220 BTC in January 2026 and have declined steadily since, with outflows exceeding $17.4Bn cumulatively as investors rotated into IBIT and competing products.
Grayscale’s structural disadvantage ran deeper than fees. Its original closed-end fund format meant shares could trade at a persistent discount to net asset value, a structure that sophisticated traders exploited to liquidate positions at scale once the ETF conversion created an exit mechanism.
That arbitrage dynamic accelerated outflows in ways that fee compression alone cannot fully explain. Grayscale has since launched a lower-fee “mini” Bitcoin ETF in a direct competitive response, though the move reads more as an acknowledgment of lost ground than a credible reversal strategy.
Fidelity’s Wise Origin Bitcoin Fund currently holds $11.1Bn in AUM, placing it third in the spot Bitcoin ETF landscape behind IBIT and GBTC, but Fidelity also recorded $89.3M in single-day outflows on certain sessions, underscoring that capital is migrating rather than being distributed.
The competitive dynamics among institutional Bitcoin ETF products show IBIT pulling away from the field, not simply trading positions with its nearest rival.
Why IBIT’s AUM Lead Signals a Structural Shift in Institutional Bitcoin Access
(SOURCE: TradingView)
The capital migration from Grayscale GBTC to BlackRock IBIT is not a story about one fund beating another; it confirms that institutional adoption of Bitcoin has entered a self-reinforcing liquidity phase.
Larger AUM compresses bid-ask spreads, tighter spreads attract more institutional volume, and higher volume generates further AUM growth.
IBIT is now deep enough in that cycle that reversing the dynamic would require a sustained fee-driven or regulatory shock that does not appear imminent.
BlackRock’s 3.87% control of the total Bitcoin supply carries implications beyond the ETF product race. With only 21 million BTC ever to exist, institutional accumulation at this scale directly reduces the circulating supply on exchanges.
Periods of supply compression combined with rising demand have historically acted as a BTC price catalyst, and BlackRock’s buying pace, $623.5M in a single week against Grayscale’s $62.3M in sales, represents net demand absorption that exchange order books feel in real time. BlackRock CEO Larry Fink has publicly described IBIT as “the fastest growing ETF ever,” a characterization the AUM data now validates structurally rather than rhetorically.
