But most of all, what we couldn't see coming was something that the instruction sheet said was irrelevant, a form of risk that wasn't reducible to the sum of individual risks: systemic risk. Systemic risk is ever present as a residual: it's the risk you cannot diversify away. But it is also emergent from within and amplified by the interlinking of individual agents' decisions in a way that is not predictable from knowledge of those individual decisions. Systemic risk, the risk that cannot be foreseen, the bullet in the chamber of the gun, is what the different elements discussed here combined to produce. Systemic risk blew the efficient market down.

Mark Blyth, Austerity, loc. 134