The brain behind the portfolio: the neurological foundations of investment decisions

Purpose This study investigates the neurological foundations of investment decision-making by exploring how specific neurotransmitters influence behavioral biases among retail investors. It aims to extend the dialogue between neurofinance and behavioral finance by providing empirical evidence of neural activity during trading. Design/methodology/approach An experimental design was used using electroencephalogram (EEG) technology to monitor brainwave patterns in six retail investors while they engaged in real-time trading. This study captured neural responses associated with attentional states, emotional arousal and cognitive processing, focusing on theta, alpha and beta waves. Findings The EEG data revealed consistent patterns of neurotransmitter-linked brain activity during investment decision-making. Increased beta activity in the frontal cortex corresponded with focused attention, while theta and alpha wave patterns were associated with emotional regulation and cognitive reflection. These findings underscore the neurochemical basis of behavioral biases such as risk aversion and overconfidence, offering partial alignment with the semi-strong form of the Efficient Market Hypothesis. Originality/value To the best of the authors’ knowledge, this study offers one of the first empirical validations of neurotransmitter involvement in financial behavior using real-time EEG data. It opens new pathways for integrating neuroscience into financial theory – particularly within culturally and ethically sensitive domains such as Islamic finance – and provides a foundation for future development of neuroadaptive, Shariah-compliant financial advisory tools.