In the dynamic realm of equity investment decisions, this study challenges the traditional assumption of investor impartiality and rationality, arguing that investors’ choices are often shaped more by beliefs and psychological inclinations than by objective reasoning alone. Drawing from behavioural finance theory, which contests the adequacy of the standard finance model in capturing the nuances of decision-making, this research delves into the psychological forces influencing private investors. Recognizing the prevalent biases coloring their decisions, the study investigates common prejudices impacting investor choices. Leveraging survey data from 375 equity investors, the research employs exploratory factor analysis and regression models to disentangle the effects of cognitive biases, such as the gambler’s fallacy, overconfidence, aversion to ambiguity, lack of representativeness, aversion to loss, and anchoring. The findings challenge the assumption of investor rationality, offering valuable insights into the complexities of financial decision-making. Notably, the study underscores a robust and positive association between these biases and equity investment decisions, shedding light on the intricate interplay between psychological factors and investment behaviour.