I've got some stocks in an industry group I'm looking at, and there's a mysterious move in the chart. I want to go back and identify which news item caused this. What's the best tool for being able to search the appropriate news articles? I'm watching the gradual shift of beta for one stock with increased volatility relative to its cousin in the same industry group. I'm trying to figure out what it was that made one company become more volatile than the other -- my initial hunch is the volume and float involved, but I'm not sure.