Does trouble come in clusters?

History is scattered with anecdotal evidence of clustering and a casual observation of the markets would seem to validate this proposition, particularly with regards to the more recent past. Take a look at skyrocketing oil prices with what seems to be no end in sight. The initial surge, triggered by a combination of a rapid acceleration in third world industrial development, a steadily weakening dollar, market turmoil related speculation and greater difficulty in finding new reserves is now being further fuelled by a confluence of random supply shocks (most recently with the militant attacks in Nigeria).
Food is showing a similar pattern in which an initial surge in prices, triggered by a steady rise in demand (again from the wealth effect of rapid development in emerging nations) combined with supply strains (resulting from ill conceived government incentives) is being further exacerbated by random events such as the devastating cyclone which hit Burma as a time when the price of rice is at record levels.
Mind you, we don't really need to confine ourselves to the universe of commodities to observe the phenomenon of clustering. Take the example of UBS, the largest wealth manager in the world, already reeling from record losses related to subprime, is now facing allegations by the U.S. department of justice for having advised clients on tax evasion.
So it would seem that trouble tends to feed on itself which means that those of us in the money management business should be paying more attention to the fat tails. Doing so may lead to improved risk management.