Purpose: This study aims to examine the impact of the International Financial Reporting Standards (IFRS) mandate and differences in national institutional quality on the underpricing of Initial Public Offering (IPO) companies. Design/methodology/approach: Multiple Difference-in-Differences (DiD) ordinary least squares estimations were conducted for 100 corporations listed on the Saudi Arabian stock market using country-level institutional quality data from 2005 to 2017. Findings: IFRS requirements and improvements in institutional quality have a combined effect on minimizing IPO underpricing. The analysis of the combined impact of IFRS requirements and differences in transparency revealed that IPO vendors leave $5 on average for IPO investors to cash out post the IFRS mandate, compared to $29 previously. Thus, IFRS serves as a quality certification instrument that alleviates IPO investors' ex ante uncertainties, even in nations with undeveloped institutions. Practical implications: The findings may be beneficial to researchers and policymakers. The results suggest that institutional quality enhancements and obligatory IFRS implementation highlight IFRS's synergistic influence on the IPO market. While European harmonization efforts drove the adoption of IFRS in Europe in 2005, Saudi Arabia's adoption of IFRS is not being driven by such initiatives (Daske et al., 2008; Persakis and Iatridis 2017). In reality, when IFRS was officially imposed in Saudi Arabia in 2008, it, like many other emerging market nations, made considerable reforms to its formal institutions. However, research on the combined impact of IFRS and disparities in institutional quality in emerging IPO markets remains sparse. Emerging markets represent more than half of economies that use IFRS. Therefore, to the best of the authors' knowledge, this study is the first to conduct an empirical investigation to identify this combined effect in emerging countries using the DiD analytical technique. Equity market legislators remain concerned regarding IPO underpricing, as it has a detrimental influence on economic growth (Bova and Pereira, 2012; Jamaani and Ahmed, 2021; Mehmood et al., 2021). Depending on the degree of information asymmetry in national stock markets, underpricing costs increase the cost of going public for entrepreneurs. Consequently, prospective private firms are discouraged from accessing equity financing through the stock markets. This is likely to impede private sector development plans, causing a negative effect on economic growth. Originality/value: Emerging countries represent over 50% of the IFRS mandating economies. However, there is insufficient research on the combined effect of IFRS requirements and improvements in institutional quality in developing IPO markets. To the best of the authors' knowledge, this study is the first empirical attempt to identify this combined effect in one of the largest developing countries. The results may aid academics and policymakers in better understanding the interaction between these two variables. [ABSTRACT FROM AUTHOR]