Quote from neophyte321:
Have you considered storing EOD volume data to a database. Pretty easy if you have a java app already developed. (Well, "easy" is relative).
I hadn't really thought about this--a standalone unusual activity application wouldn't be too hard to create and make web accessible.
This gives me some ideas for a search engine:
1) Daily volatility (specifically for day traders--I really liked stocks that would move 2%+ per day)
2) Move "abruptness" (e.g. AMD tends to trend slowly, then in one or two days SLAM the other way--smooth moves are better for options sellers)
3) Portfolio correlation for hedging purposes. (e.g. my portfolio tends to be highly correlated to the Nasdaq. Even though I trade a lot of S&P & Dow stocks, hedges using either of those indicies really don't help me. It'd be nice to know what is needed to hedge at any given time. It'd also be nice to avoid buying everything correlated)
4) Cheap/free opportunities given some criteria. For example, this month I bought an ARIA calendar spread--I risked .05 per contract with potential gain of .95/contract. That's good stuff.
5) "Good market" finder. I like BOX a lot, and would prefer equities they carry. I also like equities where the bid ask spread of options is < .15. On second thought, maybe that should be a percentage--I like GOOG and CME options, and neither trade with <.15. Hmmm...
6) Sale finder. I have this built-in to my Java app already, but it's super useful. I can search by probability breakeven/win and a bunch of other "secret" formulas that find some really interesting opportunities. (think non-traditional partial derivatives of the greeks)
Other ideas?
Impactopia does a correlation database which it looks like they've finally fixed. I love these sorts of stats.