A surge in highly speculative assets may not indicate a strong economy. It can be a sign that people feel so far behind financially that they're placing huge bets, believing in an "only up" market out of desperation rather than confidence.

A practical definition of a bubble is when investor enthusiasm pulls all potential future cash flows and upside into the present-day price. This results in an asset that offers zero forecasted returns over a long period, making it a foolish investment.

High home prices should not be interpreted as a sign of a healthy market. Instead, they indicate a system that is malfunctioning as designed, where artificial scarcity created by policy and corporate buying drives prices up. This reflects a structural failure, not robust economic demand.

When an asset sees a massive price surge, it's effectively a "price compression" that pulls years of expected returns into a short period. This raises the probability of future volatility or stagnant performance, as the future gains have already been realized.

A market enters a bubble when its price, in real terms, exceeds its long-term trend by two standard deviations. Historically, this signals a period of further gains, but these "in-bubble" profits are almost always given back in the subsequent crash, making it a predictable trap.

Asnes employs a strict framework before using the word "bubble." He will only apply the label after exhaustively attempting—and failing—to construct a set of assumptions, however improbable, that could justify observed market prices. This separates mere overvaluation from true speculative mania disconnected from reality.

Market bubbles evolve through predictable psychological stages. Phase one is buying an asset for its fundamental value. Phase two is using debt and leverage to acquire more of the appreciating asset. Phase three is pure speculation where investors, driven by greed, no longer care about the asset itself, only its potential for quick profit.

Instead of a vague label, Cliff Asness uses a rigorous test for a bubble: can you make the math work? He takes a stock like Cisco in 2000, assumes unprecedented growth for a decade, and if the valuation *still* doesn't make sense, he considers it a bubble.

While the 17th-century Dutch tulip mania is the textbook example of a speculative frenzy, a quantitative index of NFT prices reveals that their boom-and-bust cycle was even more extreme. This makes the NFT phenomenon one of the largest financial bubbles in recorded history.