Outstanding margin debt on Wall Street has surged to an all-time high of $1.5 trillion, a 77% jump over the past 14 months, according to FINRA data. This parabolic rise marks only the fourth time in three decades that margin debt has climbed at least 65% over a short period, with the prior three instances preceding major stock market declines, including the dot-com bust, the 2008 financial crisis, and the 2022 bear market. While such spikes signal heightened risk-taking that has historically proven unsustainable, long-term investors have been rewarded after downturns, with the S&P 500 never posting a negative rolling 20-year total return since 1900.