When it comes to high-impact low-probability (HILP) events, impact is so big, in both emotional and actual terms, that it swamps our understanding of the actual risk, which is often very small or unknowable.

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And there are the so-called "black swans, " events of low probability and high impact.

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However, even when dealing with a threat of low probability but devastating impact, one is obligated to err on the side of safety.

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By defining human capital as an asset that must be grown and protected, investors can begin to ascertain how human capital issues impact overall portfolio risk and the probability of achieving their long-term financial goals.

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They could include, in no particular order of probability or potentially devastating impact on the stability of financial market, default by Greece, exit by Greece from the eurozone or a much more generous rescue deal.

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"The probability is that it will cause more psychological impact and play into the enemies' hands, " he said.

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Third, investors need to make their own assessment of the probability that even some portion of the fraud allegations are correct and end up having a significant impact on the share price.

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