Research On Dynamic Topological Structure And Robustness Of Shanghai And Shenzhen Stock Markets Complex Networks

Financial markets are considered to be a typical complex system composed of a large number of interacting individuals.As a core component of the financial markets,the stock market involves complex internal and external factors.The stock price changes of listed companies are one of the typical representatives.In the past ten years,Chinese Stock Market has suffered from two major events,one is the global financial storm(hereinafter referred to as the financial crisis)that began in 2007,and the other is the abnormal fluctuation of stock prices(hereinafter referred to as stock market turmoil)that occurred in 2015.They not only cause serious losses to investors and have a huge impact on the real economy,but also bring serious challenges to the regulatory authorities.It is undoubtedly very important to study the structure characteristics and stable status of the stock market during periods of financial instability.In view of this,from the perspective of complex networks,this paper takes the global financial crisis of 2008 and the turmoil of China's stock market in 2015 as the background,combined with rolling windows analysis and simulation,to comprehensively analyze the network structure characteristics and robustness of Shanghai and Shenzhen stock markets in different periods.The results show that: First of all,the network structure of the Shanghai and Shenzhen stock markets is loose before and after the financial crisis,but it becomes very compact during the financial crisis and the stock market turmoil,and the degree distribution and influence-strength distribution of the nodes are more concentrated.This means that during the financial crisis and the stock market turmoil,the influence of Systemically Important Financial Institutions will continue to improve,and the changes in their stock prices will have a more significant impact on other companies;Secondly,the different types of events have different effects on the connectivity and robustness of the Shanghai and Shenzhen stock markets network.Regional events(stock market turmoil)have a greater impact on the market than global events(financial crisis);Again,in the short-term,the financial crisis and the stock market turmoil have not caused much impact on the robustness of the Shanghai and Shenzhen stock markets network edge.Throughout the study period,the survival rate of the two cities' networks has remained at a high level.But as the step size increases,the survival rate of the two cities' networks has dropped sharply,which means that the long-term robustness of the Shanghai and Shenzhen stock markets network related structure is declining;At last,from the perspective of network node removal and edge-to-edge changes,Shenzhen stock market has better robustness and relatively stronger impact resistance than Shanghai stock market.This paper can help to deeply investigate the structure characteristics and market status of the Shanghai and Shenzhen stock markets.At the same time,it has practical guiding significance for risk management of policy supervision and adjustment of portfolio strategy by market participants.