Interacting Effect of Ownership Structures on Audit Quality Factors and Financial Reporting Timeliness of Listed Non-Financial Companies in Nigeria

Abstract

The timely release of audited financial statements is a critical corporate governance issue in Nigeria, where reporting delays among listed non-financial firms harm investor trust, distort capital allocation, and reduce financial transparency. Previous Nigerian studies examined ownership structures in isolation and used basic statistical models that failed to account for count-based data properties. This study examined the interacting effect of ownership structures specifically ownership concentration and institutional ownership on audit firm size, audit tenure, audit fees, and auditor competence affect financial reporting timeliness. Anchored on Agency Theory alongside Resource Dependence, Stakeholder, and Signaling Theories, the quantitative study analyzed secondary data from 70 listed non-financial firms across 628 firm-year observations over ten years. Using negative binomial regression selected after confirming overdispersion in the data the study applied rigorous diagnostic tests to ensure statistical reliability across seven distinct models. The results showed that Big Four audit firm engagement and longer auditor tenure significantly reduced financial reporting lag. Conversely, higher audit fees and auditor competence increased reporting delays, driven by audit complexity and more rigorous verification procedures. Individually, ownership concentration and institutional ownership exerted weak moderating effects. However, the study’s central finding revealed a significant joint moderating effect: the simultaneous presence of both concentrated and institutional ownership triggered a governance substitution effect, which actively neutralized the timeline-compressing benefits of Big Four auditors. The study concluded that Big Four auditing and stable auditor tenure are the strongest drivers of prompt financial reporting, whereas dense dual ownership structures create administrative friction that undermines external audit efficiency. Regulators and corporate boards are advised to maintain stable auditor-client relationships and align ownership oversight with external audit processes to reduce financial reporting delays in Nigeria.