This paper examines an issue overlooked in the finance and economics literature: time variation in announcement volatility or event risk. We combine long spans of high-frequency data with a flexible parametric model of returns, which al- lows to identify announcement returns, capture intraday...

In this study, we investigate how social media coverage mitigates the under-reaction to an earnings surprise captured by post-earnings announcement drift. Based on the analysis of data collected over a nine-year period (2006–2014) from Seeking Alpha, the largest crowdsourced social media...