我們使用S&P500中500支公司股票在2020年1月15日到2020年12月31日的日資料，利用Google提供的搜尋量指數(Search Volume Index, SVI)衡量美國投資人對新冠肺炎疫情的關注程度，觀察疫情期間投資人關注度與股票報酬率的關係，並以2020年3月23日，Fed發布無限量QE政策的時間為截點，探討2020年3月23日前、後，投資人關注度和股票報酬率的關係是否會有所不同？同時本文討論產業不同及獲利能力是否造成投資人關注度與股票報酬率的相關性有所差異？另外，我們探討關注度與股票報酬波動率是否有關，且在2020年3月23日前、後有不對稱關係？
實證結果顯示（1）無論3/23前、後，SVI變動率與股票報酬率都有顯著負相關；（2）3/23前，對疫情敏感性低的產業及獲利能力較好的公司，股票報酬率受SVI的影響程度會較低；（3）SVI變動率與股票報酬波動率有顯著的正向關係，而3/23以後，兩者相關性會下降許多。

The US daily confirmed cases had been increasing since the COVID-19 broke out. However, the S&P500 index began to rebound after the Fed announced the QE policy (2020/3/23). This paper discusses whether the US stock market will be no longer affected by the epidemic. Is investors’ confidence in the market restored by the Fed policy? Is investors' concern for the impact of the epidemic decreased? We observe the daily data of 500 companies in the S&P 500 from January 15, 2020 to December 31, 2020, and use the Google Search Volume Index (SVI) as a proxy variable for investor attentions of the COVID-19. Therefore, we explore whether the US investor attentions of the COVID-19 will affect stock returns, and use the lowest point of S&P 500 on March 23,2020 to partition the sample interval. The results show that (1) The rate of change of SVI has a significant negative impact on the stock return before and after March 23. (2) The stock return of the industries with low epidemic sensitivity and companies with better profitability will be less affected by SVI before March 23. (3) The rate of change of SVI have a significant positive correlation with stock return volatility, and it will decrease a lot after March 23.

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