Markowitz's portfolio selection theory has had a huge impact not only on the financial investment industry, but also on academic research. The theory has changed the analysis from a single choice to a diversified safety option and has changed the impact characteristics of the risk-return of a single product portfolio. With regard to the MVO framework, an effective portfolio can be formed by selecting assets based on products that are associated with other assets in the portfolio and that contribute to all portfolios, rather than based on their own reward performance.
In practice, the system can achieve its expected value (expected level) through three basic methods: 1) increase the amount of investment; 2) stock mortgage; 3) mortgage. Next, we discuss each case and develop the appropriate best model, as shown below. In the first case, investors can make some financing decisions, such as borrowing money from the family without interest, borrowing money from the bank, or using their own stock as a mortgage to collect more money. Then, the problem of reaching the desired point (expected level) is equivalent to minimizing the extra budget for a given target space and decision space (constraints).
Assume a company has objectives to be achieved and products are produced. We can incorporate the concepts of financing decisions into MOP and formulate the following model