tail risk
n.β Β«βTail risk,β as it is known to quantitative traders, for where it falls in a bell-shaped probability curve. Tail risk, broadly speaking, is whatever financial cataclysm is believed by markets to have a 1 percent chance or less of happening.Β» ββIn Nature’s Casino” by Michael Lewis New York Times Aug. 26, 2007. (source: Double-Tongued Dictionary)