U.S. investors withdrew $635.6 million from spot Bitcoin exchange-traded funds on Thursday, reversing earlier weekly inflows, as a surge in oil prices due to Middle East flare-ups triggered a broader risk-off sentiment. This marks the largest single-day outflow for Bitcoin ETFs. BlackRock's iShares Bitcoin Trust and Fidelity's Wise Origin Bitcoin Fund saw the largest redemptions, with over $254 million and nearly $218 million, respectively. The outflows put downward pressure on Bitcoin's price, which briefly dipped below $81,000. Oil prices hit a five-month high after Houthi rebels attacked Saudi Arabia, raising concerns about energy supply disruptions and increasing the likelihood of the U.S. central bank raising interest rates, which typically negatively impacts risk-on assets like Bitcoin and tech stocks.