Bitcoin exchange-traded funds (ETFs) extended their losing streak into the Christmas holiday period, with U.S. investors emerging as the largest net sellers of Bitcoin amid tax-driven selling and derivatives expiry pressure.Data shows that institutional outflows remain heavy, even as analysts argue the move is seasonal rather than structural, keeping hopes alive for a post-holiday rebound.Bitcoin ETF Outflows Continue on Christmas EveAccording to data from Farside Investors, U.S. spot Bitcoin ETFs recorded $175.3 million in net outflows on Christmas Eve, despite the shortened U.S. trading session.That marked the fifth consecutive losing session, bringing total ETF outflows over the past five trading days to $825.7 million.Since Dec. 15, only one trading day — Dec. 17 — posted positive flows, when ETFs recorded $457.3 million in net inflows. Every other session has closed in the red.U.S. Investors Lead Selling PressureThe sustained ETF selling has coincided with persistent weakness during U.S. trading hours, reinforcing the narrative that American institutions are currently driving the sell-side.This trend is visible in the Coinbase Premium Index, which measures the price difference between BTC/USD on Coinbase and BTC/USDT on Binance. The index has remained negative for most of December, signaling weaker demand from U.S.-based investors.“U.S. is now the biggest seller of Bitcoin. Asia is now the biggest buyer,” said crypto analyst Ted Pillows, pointing to session-by-session return data showing stronger performance during Asian trading hours.Tax Loss Harvesting and Options Expiry BlamedMarket participants largely attribute the ETF drawdown to year-end tax loss harvesting and the impact of a major quarterly options expiry.“Most of the selling is due to tax loss harvesting, which means it’ll be over in a week,” trader Alek wrote on X, adding that Friday’s record options expiry likely dampened institutional risk appetite.He noted that these pressures are temporary, predicting that institutional buyers will return once seasonal distortions fade.Bitcoin and Ether ETF Flows Still WeakThe weakness has not been limited to Bitcoin alone. Spot Ether ETFs have also struggled to attract consistent inflows, with both asset classes showing negative 30-day moving average netflows since early November.Despite this, traders caution against interpreting ETF outflows as a definitive market top.“Price stabilizes first, flows turn neutral, and only then do inflows return,” said trader BitBull, referring to both Bitcoin and Ether ETF behavior.“For now, the data suggests liquidity is inactive, not destroyed.”Institutions Expected to Return After HolidaysWhile near-term sentiment remains cautious, analysts broadly agree that ETF outflows reflect timing and positioning, not a collapse in institutional conviction.With tax considerations largely behind the market and derivatives pressure easing, ETF flows are expected to normalize in early 2026 — potentially setting the stage for renewed institutional demand.As Bitcoin continues to consolidate, investors will be watching closely for ETF netflows to turn positive, a signal many see as a prerequisite for the next sustained price move.