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Bitcoin exchange-traded funds (ETFs) in the U.S. have recorded a remarkable 10-day inflow streak, adding more than $4.2 billion as of May 28.

At the forefront is BlackRock’s iShares Bitcoin Trust (IBIT), which has absorbed 96% of those gains, cementing its dominance in the increasingly competitive ETF market.

According to data from The Block, spot Bitcoin ETFs brought in $432.7 million in net inflows on Wednesday alone. IBIT alone attracted US$481 million, making it the only fund to record positive flows that day.

In contrast, Ark Invest’s ARKB and Fidelity’s FBTC posted outflows of $34.3 million and $14 million, respectively, while other funds saw zero movement.

IBIT’s continued strength sharpens market concentration

IBIT’s performance over the past month has been especially notable. Since April 9, it has posted 33 consecutive days without net outflows, contributing $9.31 billion. 

With $72 billion in assets under management (AUM), IBIT now ranks 23rd among all U.S. ETFs and has entered the top five by year-to-date flows.

“Another nearly $500 million into iShares Bitcoin ETF… Starting to get ridiculous,” saidNate Geraci, president of The ETF Store, in an X post on Thursday. 

Another nearly *$500mil* into iShares Bitcoin ETF…

Starting to get ridiculous.

Inflows 30 of past 31 days.

Nearly $9.5bil in new $$$.

IBIT comfortably in top 5 ETFs by inflows this year (out of 4,200+ ETFs).

— Nate Geraci (@NateGeraci) May 29, 2025

IBIT’s 33-day inflow run has made it the clear market leader among U.S. spot Bitcoin ETFs, which collectively launched in January 2024.

Since then, the total category has attracted $45.6 billion, but IBIT’s $49 billion since launch surpasses that, owing to massive outflows from Grayscale’s GBTC.

Bloomberg’s Senior ETF Analyst Eric Balchunas noted on X that IBIT is “on fire lately”, highlighting that the fund’s rise is “absolutely bonkers for a one-year-old”.

$IBIT on fire lately, now has $72b in assets, which ranks it 23rd overall, absolutely bonkers for a one year old. The next youngest ETF in the Top 25 is 12yrs old! https://t.co/i62HDtbyxJ

— Eric Balchunas (@EricBalchunas) May 28, 2025

IBIT is now outpacing long-established ETFs that have been active for over a decade.

Trading volumes also reflect IBIT’s dominance. On May 28, U.S. spot Bitcoin ETFs recorded $3.4 billion in trading volume, with IBIT contributing $2.6 billion, just shy of 80% market share by that metric.

Ethereum ETF inflows rise as crypto sector heats up

Meanwhile, spot Ethereum ETFs have also posted gains, marking an eight-day positive streak.

On Wednesday, they brought in $84.9 million in net inflows, led by BlackRock’s ETHA with $52.7 million.

Fidelity’s FETH, Grayscale’s ETH, and Invesco’s QETH followed with $25.7 million, $4.9 million, and $1.6 million, respectively. In total, the Ethereum ETFs generated $446.9 million in trading volume on the day.

The Ethereum ETFs have now generated $394.1 million in net inflows over the past eight days, bringing their cumulative total to $2.9 billion, suggesting growing institutional interest beyond Bitcoin.

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