Hendrik Pieper, Philipp Ottenstein, Henning Zülch

• The European Commission published the European Single Electronic Format (ESEF) regulation act for mandatory adoption of XBRL and hypertext markup language (HTML) usage by European listed firms. The results of prior quantitative and qualitative studies already evidence the growing dissemination of voluntary HTML-formatted financial information on the internet and reveal its perceived benefits. However, there is a lack of empirical evidence on the determinants of standardised financial reports in accordance with IFRS that are voluntarily published in HTML format, called online financial reports (OFR). We investigate the determinants of the decision of European listed firms to publish OFR from 2014 to 2019. We find that the decision of using an OFR is adversely affected by firm leverage and ownership concentration. Our findings contribute to the ongoing research on internet financial reporting and aim to improve our understanding of what determines OFR usage in an international context. Our findings may have practical implications for the disclosure strategy of listed firms.