🤖 AI Summary
This study investigates whether financial earnings announcements induce price jumps in an efficient market and addresses the empirical challenges posed by microstructure noise in high-frequency data. To this end, the paper proposes a jump detection method robust to microstructure noise, integrating high-frequency data analysis, event study methodology, and co-jump identification techniques to systematically examine the impact of announcements on both individual stocks and market-wide jump behavior. The findings reveal that earnings announcements almost invariably trigger significant price jumps in the announcing firms and substantially increase the likelihood of co-jumps among non-announcing firms and the broader market. Moreover, after 2016, post-announcement trading strategies yield returns consistent with efficient price formation, supporting the efficient market hypothesis. This work provides the first evidence of cross-asset spillover effects from earnings information, offering new insights into market efficiency and information diffusion mechanisms.