At a random moment in time, the generic behavior of any social system is to be in a trending pattern. In other words, if you ask how will “things” (e.g., the GDP of an economy, the financial market averages, the political climate) look tomorrow, the answer is that they will be just a bit better or a bit worse than today, depend- ing on whether the trend at the moment is moving up or down. This is a large part of what makes trend-following so appealing: it’s easy and it’s almost always right—except when it isn’t! Those moments when it isn’t are rare (infinitesimally small in the set of all time points, actually) and the event is usually surprising within the context of the situation in which the question about the future arises. These special moments when the current trend is rolling over from one trend to another are the critical points of the process. And if that rolling over involves great social damage in terms of lives lost, dollars spent, and/or existential angst, we call the transition from the current trend to the new one an X-event. In the natural sciences, especially physics, such a transition is often associated with a “flip” from one qualitatively different type of structure or form of behavior to another, as with the phase transition from water to ice or to steam.