Bitcoin exchange-traded funds (ETFs) only became a thing in Spring 2024 as the digital gold made its way into mainstream finance. However, they have caused quite a splash since then, growing into massive whales that control about five percent of Bitcoin’s total supply.

Some crypto enthusiasts fear that if ETFs continue accumulating BTC at the same rate, that might eventually put them in a position where they will be able to manipulate the digital gold’s price. Here’s a closer look at the facts behind these fears.

ETF Giants Load Up on Bitcoin

BlackRock’s iShares Bitcoin Trust (IBIT) is now the world’s largest corporate holder of Bitcoin. As of June 13, it owns 666,842.2 BTC, worth roughly $69.8 billion and equal to 3.18 percent of the eventual 21 million-coin supply.

Fidelity’s Wise Origin Bitcoin Fund (FBTC) ranks second with 198,794.9 BTC valued near $20.8 billion, or 0.95 percent of supply. Grayscale’s converted Bitcoin Trust ETF (GBTC) sits third at 185,196 BTC, worth about $19.4 billion and representing 0.88 percent of supply.

Combined, the three funds command 1,050,833 BTC—just over five percent of all coins that will ever exist and almost 87 percent of the 1.21 million BTC held by the entire U.S. spot-ETF sector.

Top ETF Bitcoin Holders

Top ETF Bitcoin holders

(Source: Bitbo.io)

Buying Spree: April–June 2025

IBIT’s accumulation has accelerated sharply. On April 22, the fund held 575,778 BTC. By June 12 it had added roughly 91 000 BTC: an average of 1 600 coins per trading day. The pace is fueled by record inflows, including a single-day haul of $970.9 million on April 29, IBIT’s second-largest inflow since launch. IBIT also became the fastest ETF in history to breach $70 billion in assets, achieving the milestone in 341 days.

IBIT’s BTC Holdings Over Time

IBIT’s BTC Holdings Over Time

(Source: Bitbo.io)

FBTC has been buying more cautiously. Its stash grew by about 3,200 BTC between April 21 and June 12: a daily average of 55 coins. Net flow data shows alternating bursts of demand and moderate outflows. On May 22, for example, FBTC attracted $23.5 million, while on May 30 it shed $166 million.

GBTC tells the opposite story. Since converting from a trust to an ETF in January 2025, it has steadily bled coins, losing about 8,100 BTC since April 3. Analysts attribute the drainage to fee-sensitive investors rotating into cheaper products such as IBIT and FBTC, even as spot-Bitcoin prices hover near $105,000.

Despite GBTC’s retrenchment, the net effect is unmistakable: U.S. spot ETFs have been drawing roughly 4,500 BTC a day since late April, far outstripping the 450 BTC created daily by Bitcoin’s post-halving mining rewards. This supply squeeze has become a headline driver for Bitcoin’s advance toward $110,000.

Can Three Funds Tilt the Market?

At just over five percent of ultimate supply, the trio’s holdings remain well short of a controlling stake. Bitcoin’s free-float distribution spans millions of wallets, including exchange reserves, miner treasuries, and long-term holders.

Still, IBIT’s blistering growth raises fresh concentration risks. If the fund keeps adding 90,000 BTC per quarter, it would cross the one-million-coin mark by spring 2026, giving BlackRock alone nearly five percent of supply and the entire ETF trio more than eight.

Such accumulation tightens liquidity on the margin: fewer coins circulate on exchanges, price moves amplify, and any forced selling—say, from redemptions—could swing markets. Yet structural safeguards temper the doomsday scenarios. ETFs hold Bitcoin in custodial cold storage that cannot be rehypothecated; coins are created or redeemed only against cash subscriptions, limiting direct influence over on-chain governance or transaction validation.

In practical terms, BlackRock, Fidelity and Grayscale have little incentive to “control” Bitcoin; their mandate is to mirror spot prices, not manipulate them. But their rapid accumulation has undeniably tightened supply and could magnify volatility as inflows and outflows surge with sentiment. For traders that means sharper moves; for long-term holders it means the halving-era supply shock just found a powerful new accelerant.