## 4 Discussion  
Overviews are presented in Figures 8 and 9, using bar and line charts along with event dates. It can be observed that CSI500, HSI, SSEC, SZI, and TWII had similar trends following the major social events. However, VXFXI jumped up and down during the pandemic, and it seems that VXFXI was not affected by social events. Similar outcomes can be found in Figures 10 and 11 as well. In Figure 10, when the authority proclaimed that the pandemic in Wuhan was under control on 2 March 2021, all stock market indices went up except TWII and VXFXI; in addition, in Figure 11, when the WHO stated that COVID-19 was spreading fast on 23 March 2021, all stock market indices declined; however, when more COVID cases were confirmed, VXFXI rose while others dropped. Only 57.1% of events were positive when VXFXI went up here. Based on the limited results in our experiments, it can be observed that CSI500, HSI, SSEC, and SZI were affected by COVID-related social events in mainland China the most, and TWII was also inflicted in most cases as well, but VXFXI was not concerned at all. These outcomes may be reasonable, as CSI500, HSI, SSEC, and SZI are wholly or partly regulated by the Chinese government, and TWII is located in Taiwan, which has a close connection to mainland China; the US has a close link to China as well on the economy based on the figures of trade in goods [45]. However, the influences from China on the Chinese stocks in the US are minor from our experimental outcomes. \(R^{2}\) values are given in Table 5, in which it can be witnessed that SSEC, SZI, and CSI500 act similarly (their values are close to 1); HSI and TWII have a tendency to behave comparably (\(R^{2}\) is 0.815579), while HSI's trends also remain analogous to SSEC's, SZI's, and CSI500's; conversely, VXFXI's actions are separate from all others (all values are less than 0.124431), CSI500 has a bit more influence on it, and it is independent of TWII. These statistics additionally support the observation outcomes. There were 11 positive events and 8 negative events, especially after 24 March 2021 when Wuhan's access control was lifted, which could be considered a milestone of the pandemic outbreak in China. In addition, in Table 6, we can notice that positive events caused less impact than negative events on the stock market. Investors might have less confidence during the pandemic. Concerning our hypotheses, we can conclude:  
* For H1, in most cases, all those stock market indices were influenced by the COVID-related social events in similar trends except for VXFXI. There are clear connections between COVID-19-related social events and the stock market index, and the indices may be affected by similar trends, but in our experiments, this can only be applied to five indices, and not VXFXI; its fluctuation appeared in opposed directions in many cases. * For H2, CSI500, HSI, SSEC, SZI, and TWII have similar trends in experiments; the impacts were not the same, though. Hence, different stock market indices may be \begin{table}
\begin{tabular}{c c c} \hline \hline
**Stock Index** & **Positive Event** & **Negative Event** \\ \hline SSEC & 1.82 & \(-\)1.845 \\ HSI & 1.21 & \(-\)1.92 \\ SZI & 2.37 & \(-\)1.745 \\ CSI500 & 1.94 & \(-\)2.05 \\ TWII & 1.19 & \(-\)1.56 \\ VXFXI & \(-\)3.35 & 3.68 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Changing stock market indices median values caused by two types of events. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \(R^{2}\) & **SSEC** & **HSI** & **SZI** & **CSI500** & **TWII** \\ \hline SSEC & 1 & 0.717477 & **0.912318** & **0.920767** & 0.494731 \\ HSI & 0.717477 & 1 & 0.683696 & 0.61866 & **0.815579** \\ SZI & **0.912318** & 0.683696 & 1 & **0.972093** & 0.573557 \\ CSI500 & **0.920767** & 0.61866 & **0.972093** & 1 & 0.476764 \\ TWII & 0.494731 & **0.815579** & 0.573557 & 0.476764 & 1 \\ VXFXI & 0.033837 & 0.032358 & **0.113194** & **0.124431** & **0.003594** \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Stock market index and its related major events.