Article ID: 4.2014.03
This article investigates whether and how the Japanese Financial Services Agency's mandatory use of XBRL affects investors in assessing financial information. Although regulators expect the introduction of XBRL to enhance the transparency and quality of business reporting, given the non-trivial implementation and learning costs, whether the XBRL-based disclosure reduces the information asymmetry between sophisticated and less-sophisticated investors remains an empirical question. As prior studies in other countries employing mandatory XBRL adoption provide mixed results, our analysis of the Japanese case should be somewhat insightful because Japan is one of the few countries where thousands of listed firms were forced to use the XBRL format all at once. By examining various measures in the pre- and post-XBRL periods, we provide evidence consistent with the notion that the adoption of XBRL has helped to improve the information environment, as indicated by the reduction of event returns volatility, absolute cumulative abnormal returns, changes in the standard deviation of returns, and the abnormal bid-ask spread.