The mood swings of the securities markets resemble the movement of a pendulum. Although the midpoint of its arc best describes the location of the pendulum “on average,” it actually spends very little of its time there. Instead, it is almost always swinging toward or away from the extremes of its arc. But whenever the pendulum is near either extreme, it is inevitable that it will move back toward the midpoint sooner or later. In fact, it is the movement toward an extreme itself that supplies the energy for the swing back.
