Fidelity’s Wise Origin Bitcoin Fund, trading as FBTC, attracted $310.72 million in net inflows on September 18, accounting for roughly 72% of the $433 million raised by US spot Bitcoin ETFs that day. BlackRock’s IBIT added $108 million, putting the two funds at about 97% of total inflows. FBTC has attracted approximately $10.36 billion since launching in January 2024, while combined assets in US spot Bitcoin ETFs reached $102.53 billion, or 6.29% of Bitcoin’s market capitalization. The concentration highlights how ETF subscriptions can transmit buying demand into Bitcoin markets through authorized participants and raises questions about the viability of smaller products.