Abstract
Portfolio theory is widely used in the financial field. Let us Suppose we combine the modern investment portfolio theory and diversify the investment portfolio. In that case, we can reduce investment risks and increase the possibility of satisfying all kinds of investors to obtain investment returns. In this article, we mainly consider applying the Markowitz model and the index model in portfolio theory, trying to explore its rate of return in the US market. We found that in the constructed investment portfolio, the portfolio’s return and Sharpe ratio constructed by the Markowitz model are consistent with the performance of the index model. This provides investors with a new investment perspective for portfolio construction.