I think we may just be coming to the mutual realization that the two of us subscribe to beliefs in different levels of strength of the efficient market hypothesis.
My first inclination thought after reading your most recent post was "if the stock market tends to drop and then quickly recover during small wars, shouldn't there be programmed buys triggered by wars rather than programmed sells?" Did some reading and it seems both small* and large** wars tend, if anything, to be associated with more rapid price increases in the stock market. Huh. I suppose it's a somewhat biased sample in that the analysis doesn't include major wars that the US lost. I imagine those are quite bad for the economy. Anyway, that's a bit off topic.
I'll agree that if we assume there is a set of world events that are known to scare people and drive down stock prices, but are also known to not have significant effects on the underlying economy, that these represent opportunities for the canny investor.
Whether such events exist... *shrug.* We've already discussed the issues with small (or big) wars. For the other categories:
1) Terrorist attacks. The first one that springs to mind is September 11th (and hopefully it always will be, because if it isn't, it'll mean something even worse happened). The total decline in the S&P 500, once trading reopened, was only 11.6%, which is in your business as usual category in your first post.
2) Epidemics. The last really bad one was the spanish flu of 1918-1919. But this was confounded with world war I, so it's hard to judge its actual economic effect or its impact on stock market prices.
3) Natural disasters. Hurricanes like Sandy and Ike or major earthquakes or earthquakes like Loma Prieta and Northridge cause $10s to $100 or so billion in damage, but tend to not even move the market 10%.
I certainly could be wrong here, but to me this doesn't feel like a smoking gun for a market inefficiency.
*Source:
http://www.barrons.com/articles/war-is-hellbut-not-for-the-stock-market-1492702379**Source:
https://blogs.cfainstitute.org/investor/2013/09/25/u-s-capital-market-returns-during-periods-of-war/