What Is a Market Bubble — and How Do You Spot One Before It Bursts?

A market bubble is what happens when the price of an asset detaches from its underlying value and rises instead on the force of collective belief that it will keep rising. The tulip is the most famous example. In 1637, the rarest tulip bulbs in the Netherlands were trading for six times the average annual salary. Nobody thought they were staking everything on a flower. They thought they were investing in something whose price would keep going up. It didn't. The market collapsed in February 1637, and people were left holding flowers nobody wanted (CFI, 2025).

The mechanics have not changed in four hundred years. Three conditions reliably produce bubbles. The first is the shift from use value to resale value — when people stop buying an asset for what it does and start buying it for what they can sell it for. At the peak of tulip mania, traders were exchanging contracts for bulbs that hadn't even bloomed. During the dot-com bubble, investors were buying stocks in companies with no revenue because they expected someone else to buy them at a higher price. The shift from fundamental value to narrative value is the first signal.

The second condition is leverage. When people borrow to buy assets, they amplify both gains on the way up and losses on the way down. In every major bubble — tulips, 1929, dot-com, 2008 housing — leverage turned a price correction into a crisis. When asset prices fall and leveraged buyers must sell to meet margin calls, the selling accelerates the decline, triggering more margin calls, producing more selling. The spiral is self-reinforcing.

The third condition is a compelling narrative. Bubbles do not feel like bubbles from the inside. They feel like a once-in-a-generation opportunity that only sceptics are missing. In bubble environments, sceptics are not just financially wrong — they are socially penalised. The reluctance to discuss downside scenarios is itself a warning sign (Luxury Playbook, 2026). The dot-com narrative was that the internet would change everything. It was true — but prices ran so far ahead of reality that the correction took a decade to reverse.

How to spot one: watch for valuations at historical extremes, coverage of ordinary people making extraordinary returns, borrowed money entering the market in large volumes, and the divergence between retail enthusiasm and institutional caution. When everyday investors buy aggressively while large funds quietly reduce exposure, speculation is driving prices more than analysis (Analytics Insight, 2025). The Russell 1000 Growth index traded at a trailing P/E of 39.3x in early 2026 — the widest premium to value stocks since the dot-com bubble (Winvesta, 2026). Not confirmation of a bubble. A signal worth taking seriously.

Bubbles are easier to identify in hindsight than in real time. The most useful question is not "is this a bubble?" but "what does this asset need to deliver to justify its current price, and how confident am I that it will deliver it?"