The compare of fitting between Markowitz model and single index model in different risk degree

COVID-19 outbreak impose a major threat on the economy. For such public event, government always take some measure to deal with them, and it will cause great impact market. The paper tries use 20 years of historical daily total return data for ten stocks, which belong in groups three different sectors Internet Technology Industry, financial industry, Consumer goods business, one (S&P 500) index (a eleven risky assets) proxy risk-free rate (1-month Fed Funds rate). This explore practical degree MM model IM risk by choosing market leading enterprises all walks life try expect divide risk. research show that have better fitting medium degree, be more suitable low-risk degree. Furthermore, when above 40% high level, limiting condition influence.