What was the name of the speculative boom that ended in Britain’s 1720 stock-market crash?

The speculative boom that ended in Britain’s 1720 stock-market crash was the South Sea Bubble.

The South Sea Company received special trading privileges and took on part of the British government’s debt. Its shares rose dramatically in 1720 as investors imagined enormous profits from trade with Spanish America. The company’s actual commercial opportunities were far smaller than the promotional stories surrounding it.

As enthusiasm spread, investors borrowed to buy shares, and other speculative ventures appeared. Parliament passed the Bubble Act in 1720, restricting companies formed without a royal charter, although the law did not prevent the South Sea Company’s collapse. By late 1720, the share price had fallen sharply, ruining many investors and damaging public confidence. The Mississippi Bubble in France occurred during the same period, but it was a separate financial episode associated with John Law’s company and banking system.