Abstract

This study empirically investigated the impact of corporate governance mechanisms on the stock market valuation of firms listed on the Nigerian Exchange group. Utilizing an ex-post facto research design, a balanced panel dataset of 150 firm-year observations from 10 listed companies over the period 2010–2024 was analyzed via a Fixed Effects regression model. The findings reveal that board size, board independence, and audit committee effectiveness exert statistically significant positive effects on market valuation, while ownership concentration demonstrates a significant negative impact. Among the control variables, firm size exhibits a positive relationship with valuation and leverage a negative one, whereas firm age proves insignificant. These results strongly align with Agency Theory, indicating that robust governance structures mitigate principal-agent conflicts and enhance investor confidence, thereby fostering higher market valuation. The study concludes that strengthening board independence, optimizing board composition, curbing excessive ownership concentration, and enhancing audit committee effectiveness are imperative for improving firm value in the Nigerian capital market.