In the digital era, the overwhelming volume of information and the turbulence of environmental signals have transformed individual investors' decision-making into a complex, multi-layered process. This study aims to explain the psychological and environmental mechanisms influencing investor behavior by testing a model that examines the roles of intrapersonal intelligence and HEXACO personality traits, along with the mediating effect of risk perception and the moderating role of social media. The present research is applied in terms of its objective and descriptive-correlational in nature, employing a survey design. The statistical population comprised individual investors active in the Tehran Stock Exchange, from which 235 participants were selected through convenience sampling. Data were analyzed using covariance-based structural equation modeling (CB-SEM) in AMOS software, and the validity and reliability of the constructs were confirmed based on AVE, CR indices, and the Fornell-Larcker criterion. The findings revealed that intrapersonal intelligence and personality traits exert both direct and indirect (through partial mediation of risk perception) positive and significant effects on investor behavior. Moreover, social media negatively moderates only the relationship between personality traits and investment behavior, with no significant moderating effect on the relationships involving intrapersonal intelligence or risk perception. This finding suggests that intrapersonal intelligence can serve as a cognitive shield against the scattered and unreliable signals of the digital environment. The results emphasize the necessity of transitioning from purely technical training to strengthening cognitive resilience, designing intelligent behavioral nudges, and implementing psychographic segmentation of investors.