Every Major Stock Market Crash Started with This Signal

Every major US stock market crash began with a surge in margin debt. Now, margin debt has soared to a new all-time high — higher than during the dot-com boom or the 2007 financial crisis. What does that mean for the market’s future?

Margin Debt Has Always Been a Harbinger of Crashes

Take a look at US margin debt — the borrowed money Americans use to buy stocks — measured as a percentage of the country’s total economic output. History shows every significant spike in margin debt has been followed by a major market crash. For instance, in June 1968, margin debt peaked just before the market plunged by a third. December 1972 marked the lead-up to the 1973 crash. The infamous Black Monday crash in 1987 came two months after an extreme margin debt reading in August. Then March 2000 aligned perfectly with the peak of the dot-com bubble. July 2007’s spike happened months before the financial crisis. Even more recently, January 2018 and August 2021 were followed by steep market corrections.

Every time American margin debt surged to an extreme level, a crash has happened almost immediately after. It’s a pattern as clear as day.

Today’s Margin Debt Is Unprecedented

Fast forward to June 2026. The latest data shows US margin debt has just climbed to roughly 4.5% of GDP, the highest ever recorded. This number overshadows every previous peak — from the dot-com bubble to the 2007 crisis, all the way past the meme-stock frenzy of 2021. And this figure was only released recently.

But it gets more unsettling. The official stats only count traditional margin loans through brokerage accounts. They don’t capture modern and increasingly popular ways to leverage stocks — such as leveraged ETFs, options, portfolio margin strategies, or private credit. These have exploded in recent years, often operating under the radar in riskier, high-speed markets.

Modern Leverage Fuels a Stock Market Casino

Consider the leveraged ETFs that caused turmoil among Korean investors — these same funds are active in the US, with hundreds of billions tied up. There are 2x leveraged funds on hot single stocks like Nvidia and Tesla. Then there are zero-day options where traders bet on market moves in the next few hours, not days or weeks. These instruments have seen record trading volumes, turning the stock market into a high-stakes, almost casino-like environment.

What the chart shows is really the bare minimum of leverage in the system. The true amount, considering all these hidden and fast-moving tools, is probably much higher. In other words, the margin debt floor we see is just scratching the surface of an increasingly fragile market structure.

What This Means for Investors

When margin debt climbs this high, it’s not just a number—it’s a warning light flashing brightly. Investors should be wary of the increased risk that comes with high leverage, especially in a market that’s increasingly driven by fast money and speculative strategies. History tells us that such extremes rarely end well — a correction, if not a crash, tends to follow.

Given this backdrop, some caution and preparedness seem wise. Watching the margin debt level has been a reliable way to foresee major market upheavals — and today, that level couldn’t be more alarming.