Regarding your research on inattention and short-term factors, how do you view the short-term reversal effect, analyst revisions, and flow data? Do these account for some of the short-term dynamics you discussed?
“Historically, it’s striking that a short-term reversal factor, when rooted in sound economic analysis and ignoring transaction costs, going back to the 1980s, yields an annualized Sharpe ratio close to 8. It’s ridiculous. Implementing such a strategy back then, with today’s knowledge, would have been exceptionally profitable. Although I’m not sure that hindsight always offers a valid analysis!
Essentially, with short-term reversal, you’re identifying buy or sell actions that aren’t linked to relevant news. For instance, if a company’s stock price rises significantly on an earnings announcement day, there’s typically no short-term reversal. It continues to rise. The same holds if the company’s industry or other relevant news supports the price movement. To predict a short-term reversal, you have to analyze a price movement against all available information. If there’s still a large residual – after accounting for all known factors – no reversal is expected.
But, in the last few decades, the potential profits from this approach has gone way, way down. Only firms with advanced technology might find this strategy worth it due to trading costs. For others, it’s more of a tool to gauge when to trade – like waiting to buy a stock after it peaks and before its anticipated drop. But on the other hand, this is something that’s very distinct from momentum or post-earnings announcement drifts.”