Bull markets rarely end because investors become pessimistic. More often, they end because optimism becomes excessive.

That distinction matters today. While corporate earnings remain resilient and equity markets continue to benefit from strong technology leadership, another indicator has quietly moved into territory that has historically accompanied the later stages of major market advances: margin borrowing.

According to Leuthold Group, margin debt has increased by more than 40% over the past 12 months, climbing to levels previously seen only near major market peaks in 2000, 2007, and 2021. FINRA data shows investors owed approximately $1.4 trillion in margin loans as of May, reflecting one of the most aggressive increases in leveraged equity exposure on record.

Margin borrowing, by itself, does not cause bear markets. Strong markets naturally encourage investors to borrow against appreciating portfolios, increasing purchasing power and amplifying gains. The problem is that leverage changes market behavior. When borrowing becomes widespread, markets often become more fragile because the same mechanism that accelerates gains can also accelerate declines.

For wealth advisors, the recent surge in margin debt should not necessarily trigger portfolio changes. Instead, it should reinforce a broader discussion about investor psychology, risk management, liquidity, and the importance of maintaining disciplined investment processes during periods of elevated optimism.

Leverage Is Expanding Faster Than the Market

One of the more notable aspects of today’s environment is not simply the amount of margin debt but its pace of growth.

Margin debt has expanded by more than 40% during the past year, while the S&P 500 has generated roughly a 22% total return, including dividends. Borrowing is therefore increasing at nearly twice the pace of equity appreciation.

That divergence suggests investors are becoming increasingly willing to enhance returns through leverage rather than simply participating in rising markets.

Leuthold highlighted this imbalance by examining both absolute margin debt growth and margin growth relative to market appreciation. According to the firm’s research, today’s 54% absolute margin debt growth and 26% excess margin debt growth exceed historical thresholds that have typically marked periods of excessive speculation.

Importantly, these elevated readings have historically been relatively brief. Investors rarely remain willing to continuously increase leverage once markets become volatile. Instead, the unwind often happens rapidly as falling prices trigger margin calls and forced selling.

This dynamic explains why leverage deserves attention even when economic fundamentals remain supportive.

Margin Debt Is Better Viewed as a Sentiment Indicator

Margin debt is frequently misunderstood.

Many investors assume rising margin balances directly predict market declines. History suggests the relationship is more nuanced.

Margin borrowing generally follows rising markets rather than leading them. Investors become more comfortable borrowing after portfolios appreciate and volatility declines. Strong returns create larger collateral values, allowing additional borrowing, which can further increase buying activity.

In other words, margin debt often reflects investor confidence rather than causing it.

However, exceptionally rapid increases have historically coincided with periods when investor enthusiasm becomes detached from risk.

Leuthold noted that similar surges occurred near major market peaks in 2000, 2007, and 2021. Those periods obviously differed dramatically in terms of valuation, monetary policy, earnings growth, and economic conditions. What they shared was an unusually strong willingness among investors to employ leverage.

That common behavioral pattern deserves greater attention than the calendar dates themselves.

Why Leverage Matters During Market Declines

The real risk of margin borrowing emerges after markets reverse.

Unlike traditional investors who can simply wait through periods of volatility, leveraged investors face contractual obligations. If portfolio values decline sufficiently, brokerage firms require additional collateral or liquidate positions to satisfy margin requirements.

Forced selling changes the character of market corrections.

Normal corrections involve investors voluntarily reassessing valuations. Leveraged corrections involve investors selling because they have no alternative.

Those liquidations can create self-reinforcing cycles.

Falling prices generate margin calls.

Margin calls produce additional selling.

Additional selling pushes prices lower.

Lower prices trigger even more margin calls.

The feedback loop can temporarily disconnect prices from fundamentals as liquidity becomes the dominant driver of market movements.

This process helps explain why highly leveraged markets often experience sharper declines than underlying economic conditions alone would justify.

The Rise of Leveraged ETFs Reinforces the Trend

Margin borrowing is not the only evidence of growing investor risk appetite.

Assets in speculative leveraged exchange-traded funds nearly doubled during two months last spring.

While leveraged ETFs and margin borrowing represent different investment tools, they reflect similar investor behavior: increasing exposure through borrowed or synthetic leverage to maximize returns.

These products can serve legitimate tactical purposes when used carefully by sophisticated investors. However, rapid asset growth often reflects growing confidence that market volatility will remain subdued and trends will continue uninterrupted.

History repeatedly shows that investor demand for leverage usually peaks after periods of exceptional performance rather than before them.

That timing should encourage advisors to monitor sentiment indicators alongside traditional valuation metrics.

Why This Is Not Necessarily a Sell Signal

One of the biggest mistakes advisors can make is treating leverage data as a market-timing indicator.

History offers numerous examples where elevated margin debt remained high for extended periods while markets continued advancing.

Leverage can stay elevated throughout prolonged bull markets because rising asset prices continually improve collateral values and investor confidence.

Attempting to reduce equity exposure solely because margin debt reaches historical extremes has frequently resulted in missed returns.

Instead, elevated leverage should influence expectations rather than forecasts.

Markets characterized by heavy borrowing often become more vulnerable to unexpected shocks.

The probability of larger drawdowns increases.

Volatility can rise more quickly.

Liquidity conditions may deteriorate faster than investors anticipate.

Those are important distinctions. Increased vulnerability does not necessarily imply imminent declines.

Conversations Advisors Should Be Having

The current environment provides an opportunity for advisors to shift client conversations away from predicting markets and toward preparing for uncertainty.

Many investors naturally become more comfortable with risk after prolonged gains. Success changes perception. Volatility feels lower than it actually is because recent experience has been unusually favorable.

This is precisely when disciplined advisors add value.

Clients should understand that leverage amplifies outcomes in both directions.

Borrowing against appreciated securities may appear relatively safe while markets are steadily rising. Yet the same strategy can quickly become problematic during even modest corrections.

For clients already using margin, advisors should revisit several questions:

• What purpose does the borrowing serve?
• Is leverage supporting a long-term financial objective or simply increasing exposure to recent market winners?
• Could the client comfortably meet a margin call without disrupting broader financial plans?
• Would temporary market declines force unwanted sales or create tax consequences?

These discussions are often more valuable than debating whether the market is overvalued.

Risk Management Becomes Increasingly Valuable

Periods of elevated leverage reinforce several longstanding portfolio management principles.

Diversification remains one of the most effective defenses against concentrated market stress. Portfolios heavily tilted toward the most speculative areas often experience the largest drawdowns when leverage unwinds.

Liquidity also deserves renewed attention.

Clients holding sufficient cash reserves or high-quality fixed income generally possess greater flexibility during volatile markets. They can meet spending needs without selling depressed assets and may even have opportunities to rebalance into weaker markets.

Rebalancing itself becomes increasingly important when markets become momentum-driven.

Strong returns naturally increase equity allocations beyond long-term targets. Periodic rebalancing systematically reduces exposure after gains while adding exposure following declines, helping counter the emotional tendency to chase performance.

These are not exciting strategies, but they are often among the most effective.

What Advisors Should Watch Going Forward

Rather than focusing solely on the headline level of margin debt, advisors should monitor how leverage interacts with broader market conditions.

Questions worth watching include:

• Is earnings growth continuing to justify equity valuations?
• Are credit markets showing signs of stress?
• Is market leadership broadening or becoming increasingly concentrated?
• Are retail investors becoming more speculative?
• Is volatility remaining unusually compressed despite rising leverage?

Margin debt rarely operates in isolation.

It becomes most concerning when accompanied by deteriorating fundamentals, weakening liquidity, and excessive investor optimism across multiple asset classes.

Today, elevated borrowing should therefore be viewed as one component of a broader market risk assessment rather than a standalone warning signal.

The Bottom Line

The rapid increase in margin borrowing reflects an important shift in investor behavior.

Markets are no longer being driven solely by improving corporate earnings or economic expectations. Increasingly, they are also benefiting from expanding leverage and growing investor willingness to assume additional risk.

That does not mean a major correction is imminent.

It does suggest that markets may be less resilient than headline index performance implies.

For wealth advisors, the lesson is not to predict the next downturn but to prepare clients for a wider range of outcomes. Elevated leverage has historically been less useful as a timing tool than as a reminder that optimism can become excessive, liquidity can disappear quickly, and volatility often returns when it is least expected.

The firms that navigate these periods most successfully are rarely those that forecast market peaks. They are the ones that build resilient portfolios before conditions become difficult, maintain disciplined risk controls throughout market cycles, and help clients distinguish between temporary market enthusiasm and sustainable long-term wealth creation.