US Bitcoin (BTC) spot exchange-traded funds (ETFs) witnessed a remarkable influx of $158.3 million net inflows on September 19, marking a significant shift from the previous day's net outflow, as reported by Farside Investors. The surge was driven primarily by three ETFs: Ark 21Shares ARKB, Fidelity FBTC, and Bytewise BITB, which saw net inflows of $81.1 million, $49.9 million, and $10.4 million, respectively. Contrastingly, BlackRock's IBIT ETF remained neutral, with no notable net inflow or outflow. This positive development indicates growing institutional interest in the US spot BTC ETF market. The sudden change in sentiment toward net inflows suggests a shift in investor sentiment, potentially attributed to factors such as increased regulatory clarity or positive market developments.