Measuring disclosure using 8-K filings

We construct four voluntary and two mandatory disclosure measures for 260,880 firm-quarters from 2005 through 2016 using 8-K data. The first voluntary disclosure measure is the count of 8-Ks, a proxy used in prior studies. The second and third are the count and word count of the 8-K items classified as voluntary (Items 2.02, 7.01, and 8.01) and the associated exhibits. The final voluntary disclosure measure is the count of the voluntary 8-K items and exhibits that include management guidance, conference calls, non-GAAP measures, or investor day disclosures. We document basic properties of these measures, including their cross-sectional and time-series correlations and persistence, and associations with firm-level characteristics. We show that, although the four measures are highly correlated, each captures unique aspects of firms' disclosures. Based on how the measures are constructed and supported by our findings, we contend that the word-count-based 8-K measure provides a superior proxy for firm-level voluntary disclosure.