During the bubble, a lack of profits was paradoxically an advantage for tech stocks. It removed traditional valuation metrics like P/E ratios that would have anchored prices to reality. This "valuation vacuum" allowed investors' imaginations and narratives to drive stock prices to speculative heights.

Bubbles are created when assets like startup equity are valued astronomically, creating immense perceived wealth. However, this "wealth" is not money until it's sold. A crash occurs when events force mass liquidation, revealing a scarcity of actual money to buy the assets.

The dot-com era was not fueled by pure naivete. Many investors and professionals were fully aware that valuations were disconnected from reality. The prevailing strategy was to participate in the mania with the belief that they could sell to a "greater fool" before the inevitable bubble popped.

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.

In a late-stage bubble, investor expectations are so high that even flawless financial results, like Nvidia's record-breaking revenue, fail to boost the stock price. This disconnect signals that market sentiment is saturated and fragile, responding more to narrative than fundamentals.

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.