Eighteen months after the launch of US spot bitcoin ETFs, what was once a crowded field of over a dozen issuers has narrowed to a two-firm market. BlackRock's iShares Bitcoin Trust (IBIT) and Fidelity's Wise Origin Bitcoin Fund (FBTC) now capture the vast majority of fresh institutional capital, while smaller funds have become marginal in driving overall market flows.
Data from Farside Investors shows this concentration played out repeatedly in the first half of 2026. On January 14, total net inflows hit $840.6 million. IBIT alone took $648.4 million, FBTC added $125.4 million, together representing more than 90% of all money entering the sector. On April 17, with total inflows of $663.9 million, the two funds accounted for roughly two-thirds. Even on weak sentiment days like May 1, when inflows reached $629.8 million, IBIT and FBTC jointly brought in nearly $500 million.
Mini Trust Defies the Trend
Year-to-date net flow figures, however, tell a more nuanced story. Grayscale's Bitcoin Mini Trust attracted about $333 million in net inflows this year, compared with just $83 million for IBIT, as bitcoin's 29% decline triggered waves of ETF redemptions. The Mini Trust benefits from lower fees and conversion mechanics tied to the legacy GBTC product. Yet whenever broad buying appetite returns, IBIT and FBTC remain the default destination for fresh capital.
Bitcoin's 29% Drop Squeezes Conviction
Bitcoin has fallen roughly 29% year-to-date, prompting several heavy outflow days between mid-May and early June. The selling marks a departure from earlier cycles where dips were bought. Even so, the concentration of power in BlackRock and Fidelity has only intensified, squeezing smaller issuers that lack the distribution and brand weight of the two asset-management giants.
As of mid-2026, the US spot bitcoin ETF market is effectively a duopoly. Unless bitcoin stages a dramatic recovery or regulatory shifts alter fee dynamics, the IBIT-FBTC dominance appears unlikely to fade.