I asked Sean, my resident expert on all things text, to comment on Anne Hathaway driving Berkshire Hathaway’s stock:
If only we knew exactly what these guys were doing. We’re pretty sure they’re using things like naive bayes classifiers to both 1) classify articles as being relevant to a particular stock and 2) predict return events from the text of news, and this is exactly the kind false positive you’d expect to see in both cases. If there isn’t already, there’s going to be a big set of papers on meta-anomalies, anomalies created from automated trading systems trying to take advantage of extant anomalies.
Meta-anomalies. I like that.
Update: Sean adds more detail.