Mandatory XBRL Adoption by U.S.-Listed Foreign Firms

International Financial Reporting Standards (IFRS) adopt a principles-based approach, giving managers greater discretion in interpreting accounting standards and preparing financial statements. Given this flexibility, this study examines how the 2017 IFRS XBRL reporting mandate affects SEC monitoring costs and capital market outcomes for IFRS filers. We find that IFRS filers are less likely to receive SEC comment letters, suggesting reduced SEC monitoring costs due to lower information acquisition and processing costs. Additionally, we document that stock liquidity and intraperiod timeliness improve post-XBRL adoption. However, these benefits diminish for firms using more custom XBRL tags. Despite SEC guidelines advising IFRS filers to refer to the U.S. GAAP taxonomy when appropriate IFRS tags are unavailable, we find that IFRS filers rarely do so. Collectively, our study highlights how IFRS filers respond to the IFRS XBRL reporting mandate and the implications for regulatory monitoring and capital market outcomes. JEL Classifications: G15; G38; M41; M48.