<![CDATA[This study aimed to analyze the effects of representativeness bias and regret aversion bias on the investment decisions of stock investors in Surabaya through risk propensity as a mediating variable. A quantitative research approach was employed. The population consisted of stock investors in Surabaya, while the sample comprised 155 respondents selected using purposive sampling. Data were collected through a structured questionnaire using a five-point Likert scale and were analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM). The findings indicated that representativeness bias and regret aversion bias had positive and significant effects on risk propensity. Both representativeness bias and regret aversion bias also had positive and significant effects on investment decisions. Furthermore, risk propensity had a positive and significant effect on investment decisions. The mediation analysis revealed that risk propensity significantly mediated the relationships between representativeness bias and investment decisions as well as between regret aversion bias and investment decisions. These findings suggested that investors who tended to rely on past experiences and patterns when evaluating investments and who attempted to avoid regret from previous investment decisions were more likely to exhibit higher risk propensity, which subsequently influenced their investment decision-making. Therefore, risk propensity served as an important mechanism in explaining the influence of behavioral biases on investment decisions.]]>
