US spot bitcoin funds took in about $2.39 billion over the week to September 25, and $1.71 billion of that arrived in the first two sessions, with inflows shrinking every day afterward. BlackRock's IBIT and Fidelity's FBTC together accounted for roughly four fifths of the total.
US spot bitcoin exchange-traded funds took in about $2.39 billion over the five sessions to Friday, September 25, and most of it arrived in the first two. Daily figures published by Farside Investors show net inflows of $999.0 million on Monday, $714.7 million on Tuesday, then $346.9 million, $190.7 million and $134.5 million.
Those five rows sum to $2,385.8 million. Monday and Tuesday supplied $1,713.7 million of it, or 71.8 percent, and Friday's $134.5 million was 13.5 percent of Monday's figure. Both percentages are calculated from the Farside daily series and nothing else.
A second provider reaches the same weekly total. SoSoValue's figure for the week, reported by The Block, is $2.4 billion, and its daily rows differ from Farside's by no more than $0.1 million on any session. The two series also agree on cumulative net inflows since the funds launched in January 2024, at $57.6 billion.
SoSoValue's fund-level numbers put BlackRock's IBIT at $1.2 billion for the week, Fidelity's FBTC at $701.7 million and the Ark and 21Shares fund ARKB at $294.7 million. IBIT and FBTC together come to $1,901.7 million, which is 79.7 percent of the $2,385.8 million weekly total taken from Farside. That share mixes one provider's fund-level data with the other's daily sum, which holds up here only because the two agree on the week to within rounding.
Everything outside those three funds took very little. Subtracting SoSoValue's totals for IBIT, FBTC and ARKB from the $2,385.8 million weekly sum leaves about $189 million, or 7.9 percent, spread across the rest of the field. That residual is smaller than ARKB's week on its own.
The same series moved the calendar year into positive territory. SoSoValue's cumulative 2026 net flow crossed zero during the week and stood at $934.1 million, after sitting at roughly negative $5.8 billion in mid-July. That reading rests on SoSoValue's cumulative measure alone. Farside's full-history page did not return 2026 rows when it was checked on Sunday, so the crossing could not be confirmed against a second source.
Going from roughly negative $5.8 billion in mid-July to positive $934.1 million implies about $6.7 billion of net inflows over roughly ten weeks, on SoSoValue's numbers. Both ends of that subtraction come from the same attributed series, and the July figure is described as approximate in the source, so the $6.7 billion is an order of magnitude rather than a precise total.
Cumulative assets in the bitcoin funds were $108.4 billion as of Friday on SoSoValue's measure. Assets and flows move for different reasons. The assets figure tracks the bitcoin price as well as creations and redemptions, so a week of inflows and a rise in assets are not the same fact.
Holdings worth $108.4 billion sit on $57.6 billion of net cash placed in the funds since January 2024, a difference of $50.8 billion. That difference is the mark-to-market gain on the bitcoin those funds hold, not additional money arriving.
Flow data records net creations and redemptions of fund shares. It does not identify who bought, and neither provider publishes that. Nothing in the week's rows establishes why the money arrived on Monday rather than Thursday, and the daily shape is the part a single weekly figure hides.
The funds had a comparable stretch a month earlier, when IBIT alone took $1.33 billion in the five days to August 21. Flows have not been steady since. ARKB accounted for $114.9 million of a $201.9 million outflow on the last Friday in August, ending a nine-session inflow run of just over $3 billion, before IBIT supplied most of the money that returned the next session.
The ether funds took smaller sums over the same five days. SoSoValue's rows, as reported by The Block, put BlackRock's ETHA at $326.2 million, Fidelity's FETH at $174.0 million and Grayscale's Ethereum Mini Trust at $100.3 million.
Two funds taking four fifths of a week's money is not unusual in these products. Bitwise's BSOL has taken $948 million of the $1.22 billion allocated to US spot Solana funds since they launched, a narrower field than bitcoin's but the same pattern of one or two names absorbing the flow.
