The 1720 English stock-market bubble involving the South Sea Company was the South Sea Bubble.
The South Sea Company received a government-backed monopoly over trade with Spanish South America, although its actual commercial prospects were far more limited than many investors believed. It also agreed to convert government debt into company shares, linking public finance to speculation.
Share prices rose dramatically in 1720 as investors expected enormous profits. Prominent figures, including members of the political establishment, became associated with the company or its promotion. When confidence weakened, the price collapsed, ruining many investors.
The same year also saw the Mississippi Bubble in France, making 1720 an important year in the history of financial speculation. Parliament investigated the South Sea affair, and the scandal damaged public confidence in company promotion and political oversight.