US spot Bitcoin exchange-traded funds recorded just $31.07 million in net inflows on Sept. 28, the weakest session of an eight-day positive streak, according to SoSoValue flow data. The figure marks a roughly 97% decline from the near-$1 billion daily intake recorded on Sept. 21, when institutional demand last ran at full strength.

BlackRock's iShares Bitcoin Trust (IBIT) carried the session with $54.84 million in inflows, adding approximately 657 BTC and pushing its holdings back above 800,000 BTC for the first time since May 26. Grayscale's Bitcoin Mini Trust (BTC) attracted $10.32 million. The gains partly offset outflows elsewhere: Fidelity's Wise Origin Bitcoin Fund (FBTC) shed $10.90 million, and Grayscale's GBTC lost $23.19 million. Every other product in the category registered no net movement.

The daily slowdown contrasts with the strongest weekly performance of the year. US spot Bitcoin ETFs drew $2.4 billion over the last full trading week, the largest weekly intake of 2026 and the biggest since October 2025. That surge flipped year-to-date flows positive: as recently as July the funds sat roughly $5.8 billion in the red. SoSoValue now puts month-to-date flows at $2.73 billion and 2026 net inflows at about $1.01 billion.

A shrinking bid meets concentrated supply

The deterioration in daily flows matters more now because Bitcoin is trading straight into a dense long-term-holder supply zone. BTC changed hands around $84,000 on Monday after retreating from last week's push above $87,000, according to market data cited by CryptoSlate.

On-chain analytics firm Glassnode reports that more long-term-holder coins sit between $84,000 and $85,000 than at any other level on its cost-basis distribution. That concentration raises the probability of realized selling as holders return to breakeven or slip back into profit. Glassnode has said Bitcoin needs to break through the zone and hold above it for the current recovery to extend.

During September's advance, ETF demand absorbed exactly this kind of supply. Glassnode attributed last week's roughly 4% gain partly to trust inflows, even as perpetual-futures traders and profit-takers sold into the rally.

The arithmetic of Monday's session shows how thin the marginal institutional bid has become. At roughly $84,000 per coin, $31 million equates to fewer than 400 BTC. The nearly $1 billion that entered the funds at the start of last week represented more than 11,000 BTC at comparable prices. ETF creations do not map one-to-one onto same-day spot purchases, but the comparison captures the scale of the demand decline.

What to watch

The next several trading sessions will test whether the weekly inflow momentum was a pause or a peak. A renewed pickup in ETF buying would help the market absorb long-term-holder supply between $84,000 and $85,000 and reopen the path toward the recent highs. Sustained shrinkage or a flip to net outflows would leave Bitcoin testing the heaviest cost-basis cluster on Glassnode's distribution without its primary institutional counterparty.