According to the source, U.S. crypto ETFs saw net selling of around $40.4M in BTC and $145.7M in ETH on Oct 20, indicating outflows in both products; source: original X post dated Oct 21, 2025. ETF redemptions typically lead authorized participants to sell underlying spot assets to meet withdrawals, which can add short-term sell pressure to BTC and ETH liquidity; source: U.S. SEC Investor Bulletin on Exchange-Traded Funds (ETF creation and redemption mechanics). Traders commonly monitor CME futures basis and spot market spreads during outflow days to gauge liquidity and hedging costs; source: CME Group education on futures basis and ETF-related hedging practices. Follow-up confirmation should come from the next daily flow reports published by ETF issuers and market data providers during U.S. trading hours; source: issuer daily flow disclosures (e.g., BlackRock iShares, Fidelity) and publicly reported ETF flow summaries.