South Sea Bubble
The South Sea Bubble was an eighteenth-century British financial mania centered on the South Sea Company, whose stock soared on promises of trade monopoly profits before collapsing in 1720 and ruining thousands of investors, including Isaac Newton.
The South Sea Company was founded in 1711 as a joint-stock company granted a British government monopoly on trade with South America and the Pacific Islands — territories then largely controlled by Spain. The practical trade prospects were limited, given the ongoing War of Spanish Succession and Spain's reluctance to open its colonial trade. But the company cultivated an air of enormous future promise, and the backing of prominent government figures lent it an aura of official sanction.
In 1720, the South Sea Company proposed to take over a substantial portion of the British national debt, offering to exchange government bonds for South Sea Company shares. The scheme was essentially a financial restructuring, but it was promoted with lavish promises of future profits from South American trade that had little basis in reality. Directors of the company actively talked up the stock and facilitated share purchases on credit, encouraging speculation.
The South Sea Company share price rose from roughly £100 in January 1720 to over £1,000 by August of that year. The mania spread to other ventures: dozens of speculative joint-stock companies were floated on the London market, some with genuinely absurd prospectuses. One famous example was a company whose prospectus described its purpose only as 'for carrying on an undertaking of great advantage, but nobody to know what it is.'
The collapse came in August and September 1720. As insiders began quietly selling their shares, confidence evaporated. The stock fell from over £1,000 to around £100 by December. The financial damage was widespread and severe. Many prominent figures, including members of Parliament and the aristocracy, were ruined. Even Isaac Newton, who had sold his original South Sea shares at a profit earlier in the year, re-entered the market near the peak and reportedly lost £20,000 — prompting his famous remark that he could calculate the motions of heavenly bodies but not the madness of men.
The Bubble Act of 1720, passed in part to curb the proliferation of speculative joint-stock companies, shaped British company law for over a century. The South Sea Bubble remained one of the defining events in the history of financial markets, demonstrating how government involvement and elite endorsement could amplify speculative excess to society-wide proportions.