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In 1720, the South Sea Company convinced half of England it was about to strike gold in American trade. Its shares climbed from about 128 pounds in January to nearly 1,000 by August, while the actual business grew not at all. In the autumn, the whole edifice came crashing down.
Among those caught was Isaac Newton. With an aggravating detail: he was Master of the Royal Mint, the country's foremost expert on money. Newton invested early, sold at a profit... and, watching the shares keep climbing, went back in near the peak. He lost around 20,000 pounds — a fortune worth millions today.
Physics obeyed laws he himself had written; the market obeyed none. The man who explained gravity ended up testing it on his own portfolio: what goes up without reason comes down.