标普500指数回吐稍早涨幅，一度转跌。

Group 1 - The S&P 500 index experienced a slight increase of 0.08%, reaching 6867.520, but later showed signs of a decline after earlier gains [1][2] - The trading session on February 20 saw the index open at 6843.260, with a high of 6909.870 and a low of 6836.330, resulting in a trading range of 1.07% [2] - The volume of shares traded was reported at 1.364 billion, with 216 stocks advancing and 286 declining [2] Group 2 - The S&P 500 futures were up by 0.03%, indicating a slight positive sentiment in the futures market [2] - The VIX, or volatility index, decreased by 1.01%, settling at 20.54, suggesting a reduction in market fear [2] - The related ETF, S&P 500 ETF, saw a decline of 0.44%, closing at 1.798 [2]