시장 분석가들은 월스트리트의 AI 인프라 투자 거품이 수축할 수 있으며 체계적 주식시장 파급 효과와 밸류에이션 압축의 위험이 있다고 경고합니다.

While the Dow Jones Industrial Average, S&P 500, and Nasdaq Composite have reached new highs, these gains may prove fleeting. Although the AI-driven rally has been historic, a fundamentally expensive stock market coupled with the prospect of an AI bubble poses significant risks to investors. But AI may not be Wall Street's biggest concern. Something far more sinister—with a perfect track record of foreshadowing major market declines over the last three decades—appears ready to trigger a significant correction.

**The danger signal: runaway margin debt**

Wall Street's most reliable warning comes from FINRA's monthly reports on outstanding margin debt. Margin represents capital that investors borrow from their broker, typically at interest, to purchase securities or short-sell them. When used to buy stocks or ETFs, margin acts as leverage. If a security appreciates, gains are amplified. If it moves in the opposite direction, losses are magnified equally.

Outstanding margin debt serves as a crude but powerful measure of investor risk appetite. While steady growth in margin debt is normal as the total value of public companies expands, the real danger emerges when risk-taking accelerates dramatically over a short period.

In June 2026, margin debt hit an all-time high of $1.502 trillion. This represents a 77% surge over just 14 months—an abnormally rapid climb that history suggests precedes major market declines. The last four decades reveal a clear pattern: whenever margin debt has surged 65% or more over a compressed timeframe, disaster has followed.

**Historical precedent**

From March 1999 to March 2000, margin debt jumped 80% to roughly $300 billion as the dot-com bubble inflated. When it burst, the S&P 500 lost 49% and the Nasdaq Composite fell 78%. Between June 2006 and July 2007, margin debt rose 66% to approximately $416 billion, setting the stage for the financial crisis. The resulting bear market erased 57% from the S&P 500 by March 2009. During the COVID-era stimulus period from March 2020 to October 2021, margin debt skyrocketed 95%. By January 2022, a bear market emerged, wiping out 20%, 25%, and 33% from the Dow, S&P 500, and Nasdaq respectively over nine months.

The current surge—from $851 billion in April 2025 to $1.502 trillion in June 2026—mirrors this dangerous pattern. Notably, FINRA reported that July's margin debt declined to $1.417 trillion. While one month doesn't establish a trend, history suggests we may be witnessing the early stages of a significant market correction.

**Why downturns create opportunity**

Parabolic increases in margin debt have a perfect forecasting track record. Yet history works as a predictive tool in both directions: major downturns tend to share two characteristics—they're short-lived, and they create exceptional opportunities for patient investors.

Analysis by Bespoke Investment Group on historical bear and bull markets dating back to September 1929 reveals telling statistics. The average S&P 500 bear market lasts roughly 286 calendar days (9.5 months), with no 20% or greater decline persisting longer than 630 days over the past 97 years. By contrast, the typical bull market endures for approximately 1,023 calendar days—3.6 times longer than the average bear market. Ten of the 27 bull markets studied lasted at least 1,324 days.

The data favors long-term optimism. If the risk-taking bubble is indeed in its early stages of deflation, patient investors should view any significant downturn as an opportunity to accumulate quality assets at depressed valuations.