The world’s top oil fund, United States Oil ETF (NYSEARCA: USO), booked on Tuesday its biggest daily outflows since December 2016 amid heightened volatility ahead of the OPEC+ meeting which was scheduled for the coming weekend but has since been delayed. USO saw daily withdrawals of nearly $225 million, according to estimates by Bloomberg. United States Oil ETF has been the biggest and most closely watched oil-linked exchange-traded product on the market for years. USO seeks to reflect the performance of the spot price of West Texas…