THE GOVERNANCE-PERFORMANCE NEXUS IN AN EMERGING MARKET: ANALYSING BOARD EFFECTIVENESS, OWNERSHIP STRUCTURE, AND EXTERNAL ASSURANCE IN NIGERIA

This study investigates the relationship between corporate governance and stock marke performance in Nigeria by developing an integrated governance triad comprising board effectiven ownership structure, and financial reporting oversight. Unlike previous Nigerian studies that predominantly examine individual governance mechanisms in isolation, the study considers their combined relevance within an emerging-market institutional context. Using an ex post facto correlational research design, the study analyses an unbalanced panel of 112 non-financial firms li: on the Nigerian Exchange Group (NGX) over 2013-2022. The dataset contains 986 firm-year observations, while the dynamic System GMM estimation reports 874 usable observations after application of the lag structure and estimation requirements. Stock market performance is primari measured using Tobin's Q, with market capitalization growth employed as a robustness measure. I effectiveness is measured through board independence, board size, and board activity; ownership structure through ownership concentration, institutional ownership, and foreign ownership; and financial reporting oversight through Big Four auditor affiliation and audit committee financial exp The study employs a two-step System Generalized Method of Moments (System GMM) estimator address dynamic endogeneity and unobserved firm heterogeneity. The findings indicate that boar independence has a positive and statistically significant association with firm value, while board si: board activity are insignificant. Ownership concentration exhibits a significant inverted U-shaped relationship with firm value, with the estimated turning point at approximately 67.6%. Institutiona ownership is positive and significant, whereas foreign ownership is insignificant. Audit committee financial expertise is positive and significant, while Big Four auditor affiliation has no standalone significant association with firm value. Robustness estimates using market capitalization growth pr broadly consistent results, and the reported Big Four x audit committee financial expertise interac indicates that audit quality is more valuable where competent internal financial reporting oversigh exists. The study concludes that the Nigerian market appears to place greater value on substantive governance capacity than on formal governance signals considered in isolation. The findings have implications for regulators, corporate boards, and investors seeking to strengthen governance effectiveness, minority-shareholder protection, and market confidence in Nigeria.