BlackRock’s spot Bitcoin ETF, iShares Bitcoin Trust (IBIT), is pulling further ahead on trading volume in the US market, according to The Block.
The outlet reports IBIT holds a 73.7% market share of spot Bitcoin ETF trading volume. That level of concentration matters because it shapes where liquidity sits when capital rotates, and it narrows how much “choice” the rest of the ETF lineup has to compete on day-to-day activity.
The Block also frames the moment around a sector-wide milestone. US spot Bitcoin ETFs are set to hit $2 trillion in cumulative trading volume. This is a volume metric, not net inflows. It can rise even while some funds see outflows, and it can fall even when demand is strong, if market participants churn less.
What volume leadership signals, and what it doesn’t
A 73.7% share tells you where most of the flow is going. In practical terms, larger volume typically means tighter spreads and deeper order books for that fund, especially when broader markets get active. But high trading volume does not automatically mean higher investor net contributions. It can reflect trading behavior, hedging, and rebalancing.
That distinction matters because The Block’s headline also points to “mounting outflows.” If outflows are increasing while cumulative ETF trading volume keeps climbing toward $2 trillion, the market may be processing more two-way activity than one-way demand.
Why the ETF lineup’s power keeps clustering
When one issuer commands nearly three quarters of spot Bitcoin ETF trading volume, the competitive center of gravity shifts. Other funds may still function, but their operational leverage over liquidity and investor attention declines when most activity routes through a single vehicle.
For readers tracking adoption and sentiment, the useful question becomes not just whether the market is active, but who is absorbing that activity. The Block’s data point puts IBIT in the driver’s seat for that specific measure.
The $2T milestone is a checkpoint, not a verdict
Cumulative trading volume approaching $2 trillion is a sign of scale. It also signals that US spot Bitcoin ETFs have become embedded enough for institutional plumbing to treat them as a routine channel.
Still, the headline’s emphasis on outflows is the reminder. Trading volume can hit big numbers while risk transfer flows in the opposite direction. In this market, “interest” and “net accumulation” are not the same thing.
for ETF watchers: track both sides of the ledger. The Block’s IBIT share figure tells you where volume concentrates. The outflow reference tells you that investor behavior may not be uniformly bullish. Both can be true in the same week.