"When the weather changes, nobody believes the laws of physics have changed. Similarly, I don't believe that when the stock market goes into terrible gyrations, its rules have changed"
About this Quote
The subtext is classic Mandelbrot: the world is not tame, not Gaussian, not neatly averaged into submission. His fractal view of nature and markets insists on roughness, clustering, and fat tails - patterns that don’t disappear just because they’re inconvenient. By invoking physics, he’s not claiming markets are as clean as Newton’s laws; he’s making a sharper point: even in a domain where rules are genuinely stable, prediction is hard. In a domain shaped by feedback, leverage, and human herding, pretending volatility is an anomaly becomes intellectual malpractice.
Context matters. Mandelbrot spent decades criticizing the finance industry’s reliance on elegant assumptions that make risk look manageable until it isn’t. After crashes, the narrative industry rebrands surprise as inevitability: nobody could have seen it coming, the regime has shifted, the old rules no longer apply. Mandelbrot’s analogy calls that bluff. The rules didn’t change; your picture of the rules was always a fair-weather myth.
Quote Details
| Topic | Investment |
|---|---|
| Source | Help us find the source |
| Cite |
Citation Formats
APA Style (7th ed.)
Mandelbrot, Benoit. (2026, February 16). When the weather changes, nobody believes the laws of physics have changed. Similarly, I don't believe that when the stock market goes into terrible gyrations, its rules have changed. FixQuotes. https://fixquotes.com/quotes/when-the-weather-changes-nobody-believes-the-laws-9914/
Chicago Style
Mandelbrot, Benoit. "When the weather changes, nobody believes the laws of physics have changed. Similarly, I don't believe that when the stock market goes into terrible gyrations, its rules have changed." FixQuotes. February 16, 2026. https://fixquotes.com/quotes/when-the-weather-changes-nobody-believes-the-laws-9914/.
MLA Style (9th ed.)
"When the weather changes, nobody believes the laws of physics have changed. Similarly, I don't believe that when the stock market goes into terrible gyrations, its rules have changed." FixQuotes, 16 Feb. 2026, https://fixquotes.com/quotes/when-the-weather-changes-nobody-believes-the-laws-9914/. Accessed 19 Feb. 2026.



