Suppose there is a probability of Russia using a nuclear weapon on Crimea. You have a view on this probability, and other market participants also have a view on this probability, but you don't know what their views are. In order to determine which way you need to invest in Ukrainian and Russian stocks/currencies/etc. to express your view, you have to become an absolute expert in any of the assets in question so that you can estimate the implied probability of current market prices.
Efficient markets. Either you think you have non-public information/superior analyses to current participants or you don't; in the latter, you should not trade at all. In the former situation, then the current prices reflect all publicly-available information about the net future prospects of Russian/Ukrainian-related assets, and you don't need to become an expert on anything except the use of nuclear weapons (which you believe the markets are currently ignorant of) since the prices of those assets are already correctly priced with neither excess gains nor losses expected. You can simply buy/sell as your unique insight tells you to.
(Your real problem is whether you can buy enough to make it worthwhile and lack of diversification & volatility means you may be right, buy appropriately, and lose anyway, but that's why you work for a hedge fund.)
The efficient markets criticism works if you have non-public information that clearly points to a greater or lesser risk than what market participants think, but it doesn't work for non-public information that is different from market sentiments by only a degree. If you have private information that the Russian government has a 2% chance of using a nuclear weapon on Crimea (perhaps you know they will roll a 50-sided die and use them on a 1), but you can't tell whether the current market prices imply a 0% to 4% probability, you have no way of using your pri...
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