The Impact Of COVID-19 On CSI300 Stock Market

The outbreak of the COVID-19 in 2020 has severely hit the domestic economy.The stock market is known as a barometer of the economy and can respond quickly to changes in economic activities.The slump in Chinese stock market on the first day of trading on February 3,2020 shows that the COVID-19 has had a strong impact on the stability of Chinese stock market.Therefore,exploring the impact of the COVID-19 on Chinese stock market has certain guiding significance for stabilizing Chinese stock market.Firstly,this paper collected the daily closing price of CSI300 from October 11,2018 to March 31,2021 for a total of 600 trading days,and 228 representative stocks were selected as nodes in the network,the daily closing price of the day was processed by the Pearson correlation coefficient as the connecting edge to construct the network.Furthermore,the stock market network for two periods before and during the COVID-19 is established based on the minimum spanning tree,and the impact of the COVID-19 on the structure of the stock market network is analyzed.Then,the threshold method is used to construct the stock market network to explore the small world and community structure of the network.Finally,the network state after the stock market encounters huge risks during the COVID-19 is simulated by using the network attack,and the network after the attack is further explored according to the vulnerability index.Through the above research process,this paper finds that in the minimum spanning tree network model,the normalized tree length in the network decreases sharply after the outbreak of the COVID-19,indicating that it has a certain role in identifying the crisis;the industry analysis of the core node companies in the network shows that the financial industry plays an important role in the stock market network.In the threshold network model,by calculating the average path length and the clustering coefficient in the stock market network,it is concluded that the network has a small world characteristics;by analyzing the modularity of the network,it is found that the modularity value of the network during the COVID-19 is greater than that before the COVID-19,therefore the network shows better community division when during the COVID-19.After attacking the stock market threshold network during the COVID-19,it is found that the topological structure of the network has had great changes,which is reflected in the decrease in the density of the network,the increase in modularity,and the increase in the number of communities.In addition,the network vulnerability indicator shows that the overall anti-attack ability of the network is weak.