Investment Enlightenment Based On Dynamic Superposition Effect Of Default Risk Causes Of Urban Investment Bonds

In 2020,the number of various types of urban investment bonds issued reached 5574,and the issuance scale of urban investment bonds reached 4.97 trillion yuan,an increase of 31%and 24%respectively over the same period in 2019,and the maturity of urban investment bonds in 2020 was 2.72 trillion yuan,the highest level in history.When a large number of urban investment bonds exist,the possibility of default of urban investment bonds is particularly prominent.It is very necessary to regard urban investment bonds as an important debt type that has not been issued,understand the specific causes of its default risk,and prevent and resolve its default risk.Therefore,this paper takes "urban investment bonds" as the theme and takes risk causes as the research point,which is different from the previous conclusions of static causes analysis.This paper explores the dynamic relationship between the causes of objective selection,which has more practical significance and can provide enlightenment for investors to make correct investment choices.This paper takes "basic statement-research basis-characteristic analysis-static analysis-dynamic analysis" as the research path.Firstly,it combs the existing literature to understand the research status related to the causes of default risk of urban investment bonds and dynamic analysis model,therefore,it provices reference for selecting the causes and constructing the model;Then it analyzes the characteristics of urban investment company and urban investment bond,and reveals the source of risk and the basis of topic selection;Then,based on the "point line surface" threedimensional induction of the causes,18 causes are determined,a sample data set is constructed for 11792 urban investment bonds that have existed during 2015-2020,and the cause indicators are sorted by random forest importance and static analysis;Finally,411 urban investment bonds that continued to exist from 2015 to 2020 were used as individuals to construct panel data.The panel vector autoregressive(pvar)model was selected to design three groups of comparisons:The comparison between pvar estimation and impulse response between causes,the comparison between pvar estimation and impulse response of urban investment bond risk premium to various causes,and the comparison between static and dynamic’ conclusions,in order to complete the discussion of the core issuesThe results show that:1)there is a dynamic superposition effect among the causes,and the actual impact on the default risk of urban investment bonds depends on the dynamic superposition effect;2)Random forest can rank the importance of causes,and pay special attention to each cause according to the ranking results;3)Net profit margin is the inevitable guarantee for the repayment of urban investment debt.Under the realistic background of the current market-oriented transformation of urban investment companies,the implicit guarantee of the government has an inhibitory effect on the default risk of urban investment debt.There is a long formation period of industrial agglomeration.The impact direction of Urban Investment default risk is different in different periods.Investors should observe the causes in combination with objective facts;4)Under the action of dynamic superposition effect,investors should determine the regional and individual investability of urban investment bonds according to the final impact intensity of each cause.It is an important innovation of this paper to summarize the causes and combine dimension reduction model with dynamic research model,the objective selection of causes for dynamic analysis,and the improvement of the shortcomings of existing studies that mostly conduct static analysis or scholars subjectively select a few causes for dynamic analysis.This paper also has some shortcomings.Firstly,this paper only explores the dynamic effect of the causes after dimensionality reduction,rather than all the identified causes;Secondly,in the process of three-dimensional identification of causes,there is a certain subjectivity,and there may be omissions of other potentially important causes.