美股每日的涨跌概率不是刚好50：50，而是上涨的日子略多点。算是炒股的基本常识吧。

Based on historical data (1996–2021), the U.S. stock market averages roughly 53% to 55% up days, with 45% to 47% down days, indicating a slight positive bias over time. In daily trading, the market often behaves roughly 50/50, but generally, the number of up days slightly exceeds down days over longer periods.