Americans are borrowing more money to buy stocks than at almost any point on record. US margin debt hit $1.4156 trillion in May, FINRA data shows, up 53.7% from a year earlier and up 8.5% from April alone. That puts margin debt relative to the M2 money supply at 6.17%, just below the all-time high of 6.35% reached during the dot-com bubble.
Margin debt as a share of GDP or market capitalization has peaked close to major market tops in 2000, 2007, and 2021, with sharp corrections following in each case. The relationship works in both directions, since the steepest historical stock-market drops, including 1929, 1987, and 2020, all coincided with rapid contractions in margin debt as forced selling accelerated declines.
The borrowing is piling into an unusually narrow slice of the market. The 10 largest stocks in the S&P 500 now account for a record 41.2% of the index, up from roughly 20% in 1990. Much of that dominance traces to AI-linked names including Nvidia, Microsoft, and Alphabet, which have driven the bulk of the index’s earnings growth and price gains over the past two years.
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Much of the current margin debt surge traces to leveraged trading vehicles rather than traditional stock-picking. Leveraged exchange-traded funds, which amplify daily index moves by two or three times, nearly doubled their combined assets to $220 billion between late March and early June.
Barclays estimates leveraged funds have purchased roughly $300 billion in derivatives since March, part of a broader pattern of investors from hedge funds to retail traders adding leverage to chase gains in AI-linked stocks.
A 3x leveraged semiconductor ETF dropped 31% in a single trading session on June 5, illustrating how quickly amplified bets can unwind when a narrow, richly valued corner of the market turns.
Not every analyst treats the trend as an imminent warning sign. Some of the rise in reported margin debt is mechanical, since rising stock prices force short-sellers to post more collateral, which is often financed through margin loans of their own, meaning the figure partly reflects where prices already are rather than predicting where they’re headed next.
The same FINRA data tracked monthly comes with its own caveat, since margin debt is inherently backward-looking and there have been too few historical peak-to-trough episodes to treat it as a reliable leading indicator of a major selloff.
