Say, for example, I want to find all stocks that fell (or increased) by 600% or more in 2008 (or better yet, over 2008 through 2009). How do I do so? Does it have to be done manually?
you made me check something,back in 1999 i seen this and they are still in business,not bad they have custom screens just as you ask or they did in the past http://www.investertech.com/default.asp
This is a trivial to program, if you have the (accurate) data. If your programming skills are poor, time to start learning. Your competition already has done so. Also, stocks can't fall by more than 100%. I think you need to rethink your question.
Yep - we are talking about stocks here, not other instruments that have other obligations. I don't know which planet you trade on, but stocks can't fall further than zero. Of course your account balance can go negative if you trade on margin, but we're talking about a _stock_ falling more than 100%.