Market peaks may seem particularly frightening. Like the crest of a roller coaster, they may incite panicked concern that the only course from here is down. Unlike roller coasters, though, such anxiety is unattached from observable truth. While we can see the coaster track, there is no rule in investing that determines future trajectories. Nonetheless, we may find comfort in market history. Though the answers to “by how much?” and “for how long?” only may be determined in hindsight, we may use market history to show probabilities of future outcomes given starting circumstances. For those wary of the fact that December 2017 marked yet another peak for the S&P 500 Index, this month we look to provide detail as to what the future held for past market peaks in hopes that these data will prove comforting support for a chosen level of market exposure.