However, because several years can occur between fat-tail events, investors become complacent about option-writing.

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Risk management consultants say the models that banks use to predict the risks of their exposures don't work in these so-called "fat-tail" events, shocks that move otherwise predictable swings outside the parameters of clever computer programs and their keepers.

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Guenther says the plan was to start with the magazines from the short, fat part of the curve rather than the long-tail niche properties.

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Now I hear and you hear that this is, well, kind of dismissed: This is a terrible thing that happens every once, every hundred years--or it's a Black Swan or Fat Tail.

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It, in fact, has a very fat tail, and in 2008, that portfolio would have lost 37%, where a risk-parity portfolio would have lost less than half that amount at the same targeted level of volatility.

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