The encyclopedia · Trading & Investing · Financial decision · 1720
The South Sea Bubble ruined thousands — and even Isaac Newton lost a fortune
In 1720 shares in the South Sea Company soared on speculation, then collapsed, ruining thousands of investors. Isaac Newton lost a fortune in the crash.
South Sea Company · 1720-09
What happened
The South Sea Company was a British joint-stock company founded in 1711, granted a monopoly on trade with South America — including, notoriously, the contract to supply enslaved Africans to Spanish colonies (the Asiento), a trade that never yielded the profits promised. In 1720, the company proposed to take over much of Britain's national debt, and its stock became the object of a national speculation frenzy.
The share price soared from about £128 in January to over £1,000 by the summer of 1720, fueled by hype, insider dealing and easy credit. The company's directors stoked the mania while quietly selling their own shares. Then the bubble burst: the price collapsed back toward its starting point, ruining thousands of investors who had bought at the top, many with borrowed money.
Even Isaac Newton, one of the greatest minds in history, was caught. He sold early for a profit, then bought back in near the peak and lost about £20,000 — a fortune. He is said to have reflected: 'I can calculate the motions of the heavenly bodies, but not the madness of men.' The crash led to the Bubble Act, which restricted the formation of joint-stock companies for over a century, and it remains one of the most famous speculative manias in history.
Why it happened
- The South Sea Company's stock was driven by hype and speculation, not by real profits — its core trade (including the slave trade) never delivered the promised returns.
- Easy credit let investors buy shares with borrowed money, amplifying both the rise and the crash.
- The company's directors stoked the mania while quietly selling their own shares (insider dealing).
- Investors bought at the top on the belief that prices would keep rising forever — the classic bubble psychology.
The lesson
When a price is driven by the belief that it will keep rising, rather than by real value, it is a bubble — and the last buyers hold the loss. Newton could calculate the motions of the planets but not.
Aftermath
The South Sea Bubble is taught alongside the Dutch tulip mania as the original case study of a speculative bubble: a story, easy credit, a crowd, and a collapse. It led to the Bubble Act, which restricted joint-stock companies for over a century, and it shaped financial regulation and the public's understanding of manias for generations. Newton's lament — that he could predict the stars but not the madness of men — remains the enduring summary: markets are driven by psychology as much as fundamentals, and the belief that 'this time is different' is the most expensive sentence in finance.
Sources
- South Sea Company — Wikipedia (1720 bubble, collapse, Newton's losses, Bubble Act)
- The South Sea Bubble: When Britain Gambled on a Trading Company — Market Histories
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