Analysis on Portfolio Selection under Markowitz Model and Index Model before and After Covid-19 Outbroke

The worldwide outbreak of COVID-19 in early 2020 has brought great challenges to global economic development. Against this background, how choose a better portfolio invest becomes problem. purpose the study is find effect on different type portfolios under one benchmark and four constraints by utilizing Markowitz model Index model. This paper selects stock index six stocks from three industries form portfolio. Portfolio which only consider risks both returns with are presented respectively. empirical results show that performed best before were difficult choose. However, statistics after shares similarity. In general, when weight SPX zero shows performance model, sum absolute values all weights less than or equal two also contributes provide guideline conduct investors investment models COVID-19.