On May 22, the BlackRock iShares Bitcoin Trust ETF (IBIT) topped all U.S.-listed exchange-traded funds in daily inflows for the first time, dethroning VOO.
Notably, it surpassed longstanding leaders such as Vanguard’s S&P 500 ETF (VOO) and iShares Core S&P 500 ETF (IVV). According to Bloomberg Senior ETF Analyst Eric Balchunas, this marked a significant milestone, fueled by what he described as a “feeding frenzy” in response to the new price highs.
$IBIT was #1 among ALL ETFs in flows yesterday, a first I believe (the Mighty VOO took a rare day off), and a byproduct of the ATH-induced feeding frenzy volume mentioned below. IBIT's Pac-Man spree is now up to about $8b in 5wks. BTC ETFs lifetime net flows (most imp metric) at… https://t.co/ifkkwn2GXw pic.twitter.com/21pqh3UA4n
— Eric Balchunas (@EricBalchunas) May 23, 2025
Specifically, the IBIT ETF saw a single-day inflow of $877.18 million, contributing to approximately $8 billion in total inflows over the past five weeks.
According to Bitwise President Teddy Fusaro, the performance of Bitcoin ETFs suggests their market introduction has been among the most successful in ETF history based on asset accumulation and inflow metrics to date.
ETF Flow Rankings Shift Amid Bitcoin Rally
This record-setting day pushed IBIT to the top of the ETF inflow leaderboard. Over the last month alone, the fund accumulated more than $7.5 billion, reflecting strong market interest in digital asset-backed products.
Balchunas added that May 21 marked IBIT’s second-highest trading volume ever, closely trailing activity from January 23—another date aligned with a Bitcoin all-time high. Additionally, lifetime net flows for all Bitcoin ETFs combined have now reached $44.5 billion, signaling their growing presence in traditional portfolios.
Meanwhile, Treasury bond ETFs also saw elevated demand. iShares’ TLT ETF, which targets long-duration U.S. government bonds, posted $851.83 million in daily inflows and more than $2.2 billion for the week.
While not surpassing IBIT, this performance indicates growing investor interest in duration exposure, potentially due to evolving interest rate expectations or broader risk management strategies. Notably, VOO remained strong with $558.06 million in daily inflows and $14.66 billion over the last month.
Institutional Momentum
CoinShares data for the week ending May 19 further supports the bullish trend, showing iShares ETFs in the U.S. leading with $907.80 million in weekly inflows.
Month-to-date, iShares pulled in $2.98 billion, bringing the year-to-date total to $9.04 billion. The product now manages over $69 billion in total assets under management (AUM).
In contrast, Grayscale Investments LLC continued to experience net outflows. The Grayscale Bitcoin Trust (GBTC) recorded $42.46 million in outflows over the week, with monthly losses of $152.77 million and year-to-date net redemptions totaling $1.62 billion. Despite managing $29.67 billion in AUM, these figures suggest a notable rotation away from higher-cost legacy products toward newer, lower-fee alternatives.
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