The South Sea Bubble was the British stock-market bubble that collapsed in 1720 after South Sea Company speculation.
The South Sea Company received a government monopoly over trade with Spanish South America in 1711, although its actual trading prospects were limited. In 1720, the company proposed converting much of Britain's national debt into its shares. Political support, easy credit, and aggressive promotion drove the share price sharply upward.
The price peaked at about £1,000 in August 1720 before confidence failed. Selling spread through the market, ruining many investors and damaging public trust in Parliament and financiers. The collapse is often discussed alongside France's Mississippi Bubble, which burst in the same year, but the two schemes were separate. The episode helped inspire later British restrictions on joint-stock companies under the Bubble Act of 1720.