Customers for company managers are their most important asset, so they consider communication with customers as a beneficial interaction. Indeed, all customers play an equal role in the success of organizations. When most markets are mature and getting new customers is difficult, companies have an urgent need to maintain loyal and key customers so that acquiring a new customer, as experts say, costs six to nine times more than keeping current customers. This research determines the relationship between the Herfindahl index, systematic risk, and the cost of stakeholders’ equity. Its statistical population consists of companies admitted to the Tehran Stock Exchange. 119 companies as sample population were selected from the statistical population (510 people) by stratified random sampling method. The results showed a relationship between the Herfindahl customer index and the cost of stakeholders’ equity. There is also a relationship between systematic risk and the cost of stakeholders’ equity. Such a reaction by investors can be because of the asymmetry of information. Their reaction to changes in cash is not because of the profitability of investments and the growth rate of companies in the coming years, but only for the financial limitations of companies.