Hendrik Pieper, Toni W. Thun, Emily Heineking, Henning Zülch

• Not only the content but also the format of financial reporting has been focused by regulators and researchers over the past years. The European Commission passed the European Single Electronic Format (ESEF) regulation for mandatory adoption of HTML for listed firms in 2020. While existing research shows positive relationships of in-ternet financial reporting (IFR) and, e.g., transparency and value relevance, the IFR literature lacks quantitative studies that focus on the quality of audited and standardized financial reports published in HTML format, known as online financial reports (OFR). We analyze a sample of 155 European listed firms and investigate the relationship between corporate governance measures and an OFR quality score. Our findings support the increasing importance of OFR before the ESEF mandate and show that ownership structure significantly impacts the format-specific qual-ity of OFR. Our findings contribute to the relationship of corporate governance measures and advanced financial reporting formats.