Looking back at the past twenty years, however, financial  BIS central bankers’ speeches  1  crises have occurred more frequently than would be assumed in a normal probability distribution. In any case, both types of tail events have a devastating impact on the financial markets, the economy, and society (Slides 4, 5, and 6).
In cases where extremely rare events far beyond the end of the tail occur and where rare events within the tail happen more frequently than anticipated, the common feature is that such unanticipated events invite devastating turmoil.