On October 19, 1987, the Dow fell 22.6% (-508 points) in a single session — the largest one-day percentage drop in its history. It wasn’t just the news (trade deficit miss + takeover-tax bill the prior week). The Brady Commission found the crash was amplified by $60-90B of “portfolio insurance”: computer programs that automatically sold index futures as prices fell, feeding a loop — stocks fell, programs sold, stocks fell harder.

Today’s version: 0DTE SPX options averaged a record $2.3 trillion in daily notional in Q2 2026 — over 60% of all SPX options volume (Cboe). When the market drops, dealers on the other side of that flow must hedge by selling into the fall too. Same feedback loop. Faster machine.

Historical comparison only — not a prediction of any future crash.

Sources: Federal Reserve History of Black Monday; Brady Report (1988); sociustrades.com/blog/black-monday-1987-portfolio-insurance; Cboe Global Markets Sep 2026 derivatives report; tokenpost.com 0DTE notional data.

This video is for education and entertainment only — not financial advice. Do your own research or consult a licensed advisor before investing. Markets involve risk, including loss of principal.

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