The primary goal of the research is to determine how the emotional inclinations of investors affect the link between capital cost and systematic risk for businesses listed between 2014 and 2018 on the Tehran Stock Exchange. They work for themselves. The mood of investors is likewise erratic. There are 112 firms in the research's statistical sample. A descriptive-correlation study with an applied approach is the methodology used. The library technique was used to get the data for the theoretical foundations segment, and the financial document documenting method was used to gather the data for the hypothetical testing section. The multiple correlation and regression approach is typically used for hypothesis testing. As demonstrated by the findings, systemic risk and capital cost have a clear and substantial link, but this relationship is also weakened by investors' emotional biases. The financial leverage and the ratio of accruals to the cost of capital are directly and significantly correlated, according to the results of the control variables, and the size of the firm and the cost of capital are significantly correlated as well. The ratio of operational cash flows to capital costs was also not shown to be significantly correlated.
