This study examines how psychological factors like cognitive biases, fear of losses, and overconfidence affect investment decisions among individual investors. Using data collected from 317 participants, the research explores the impact of these behavioural patterns on portfolio diversification, risk-taking, and decision-making. The findings reveal that fear of losses significantly influences investment behaviour, often leading to overly cautious choices and limited diversification. The study also shows that financial literacy helps reduce the influence of biases, enabling more rational investment decisions. However, overconfidence was not found to have a strong effect on risky trading behaviour. Additionally, there were no major differences in cognitive biases between male and female investors. Overall, the research emphasizes the importance of financial education and self-awareness in improving investor decision-making.