A couple notes:
- It might be a good idea to note stock:market divergences on your chart
- Don't know where your parsing your news, but you might want to incorporate a filter for SEC filings and PR releases along with a way to eliminate the fluff/SEO (Motley Fool comes to mind)
It seems (as blurry pointed out) that you are assuming that news leads/lags a stock. There's also a whiff of efficient market theory in there, and at the expense of pissing off half of HN, the markets aren't efficient.
Other than that, I find a hard time finding the difference between what you have and other tools I use.