According to the source, US spot BTC ETFs recorded $1.23 billion in weekly net outflows and US spot ETH ETFs saw $311.8 million in net outflows. These reported outflows indicate net redemptions that typically require authorized participants to sell underlying BTC and ETH to meet cash needs, increasing realized sell pressure, per ETF creation and redemption mechanics disclosed by ETF issuers and the SEC. For traders, sustained weekly outflows reduce marginal buy-side demand from the ETF channel and can tighten on-exchange liquidity during US hours, per standard ETF flow accounting and primary market mechanics disclosed by ETF issuers and the SEC.

According to @FarsideUK, BlackRock’s Bitcoin ETF recorded a daily flow of negative 268.6 million US dollars on Oct 18, 2025, source: Farside Investors post on X and farside.co.uk/btc. Farside’s Bitcoin ETF flow dashboard lists daily fund flows in US dollars along with data notes and disclaimers for verification, source: farside.co.uk/btc.

According to @rovercrc, more than $4B has flowed into ETH ETFs this month while BTC ETFs saw $624.48M in outflows, signaling a sharp demand rotation between the two assets (source: @rovercrc on X, Aug 30, 2025). According to @rovercrc, this divergence hints at a potential altseason, implying potential relative-strength upside in ETH/BTC and higher-beta altcoins if the reported flow trend persists (source: @rovercrc on X, Aug 30, 2025). According to @rovercrc, traders can focus on tracking daily net flows of ETH vs BTC ETFs and watch ETH/BTC for breakouts as confirmation before increasing altcoin exposure (source: @rovercrc on X, Aug 30, 2025).

According to QCPgroup, altcoins experienced a sharper sell-off last week, with SOL losing nearly 20% and ETH dropping close to 10%. ETF flows failed to support prices, as BTC recorded its second-largest daily outflow and ETH saw its fourth-largest outflow on Friday. This trend suggests that recent institutional demand is not providing short-term price support, which may impact trading strategies and market sentiment for BTC, ETH, and SOL. Source: QCPgroup.