U.S. spot Bitcoin ETFs posted $462.7 million in net outflows last week, ending a three-week inflow streak that had ranked as the strongest of 2026, according to flow data compiled by Farside Investors. Over the same holiday-shortened four-day trading period, spot Ether ETFs moved in the opposite direction and attracted $196.9 million in net inflows.

The divergence marks the first weekly reversal in Bitcoin ETF demand after three consecutive weeks of gains, and it concentrates attention on how institutional allocators are rotating between the two largest crypto-linked ETP wrappers in the U.S. market.

Four Consecutive Sessions of Bitcoin Outflows

Farside's data shows U.S. spot Bitcoin ETFs bled on every trading day from Tuesday through Friday. The funds lost $166.8 million across the first two sessions of the shortened week.

Selling then accelerated sharply. On Thursday, Bitcoin ETFs recorded $282.7 million in net outflows — the largest single-day withdrawal since July. Friday brought only partial relief: the funds still shed another $13.2 million, extending the outflow streak to four consecutive sessions.

ARKB, GBTC and IBIT Lead the Withdrawals

The distribution of outflows was broad rather than concentrated in a single product. ARK 21Shares Bitcoin ETF (ARKB) recorded the largest weekly withdrawal at $234.2 million.

Grayscale's Bitcoin Trust ETF (GBTC) followed with $129.1 million in outflows, while BlackRock's iShares Bitcoin Trust ETF (IBIT) — the largest spot Bitcoin fund by assets — saw $52.5 million leave. Fidelity's Wise Origin Bitcoin Fund (FBTC) lost approximately $50.7 million.

The picture for the month remains constructive despite the weekly reversal. Through Friday, Bitcoin ETFs had accumulated roughly $307.3 million in cumulative net inflows for September, meaning the latest selling has not erased the month's institutional demand.

Ether ETFs Finish Strong on a Late-Week Surge

U.S. spot Ether ETFs started the week with mixed flows: $24.3 million in outflows on Tuesday, $34.7 million in inflows on Wednesday and another $29.9 million in outflows on Thursday, per Farside Investors.

Friday changed the arithmetic entirely. Ether funds attracted $216.4 million in a single session, more than offsetting the previous three days and pushing the full week into positive territory at $196.9 million.

BlackRock's iShares Ethereum Trust ETF (ETHA) drove that surge with $148.8 million of Friday's inflows. The 21Shares Core Ethereum ETF added another $29.1 million.

One Week, Two Readings

The operational significance of the split depends on whether it persists. The Ether weekly gain was heavily concentrated in a single Friday session, and Bitcoin funds remain net positive for September — factors that caution against reading the reversal as a structural break in demand.

Still, the scale of Thursday's $282.7 million Bitcoin withdrawal and the breadth of outflows across ARKB, GBTC, IBIT and FBTC indicate the selling was not isolated to one issuer's product. If BlackRock-led Ether inflows continue alongside Bitcoin weakness in the coming sessions, issuers and market makers may need to reassess allocation assumptions built on Bitcoin-first ETF demand.

The next several trading sessions will determine whether investors are temporarily rotating toward Ether exposure or whether Bitcoin ETF demand is weakening more broadly. Until then, Bitcoin funds face renewed redemption pressure while BlackRock-anchored demand keeps Ether products in positive territory.