What was the name of the 1720 English market bubble that collapsed after rapid speculation?

The 1720 English market bubble that collapsed after rapid speculation was the South Sea Bubble.

The South Sea Company received a monopoly over British trade with Spanish South America in 1711, although the commercial opportunities were far more limited than many investors imagined. In 1720, the company proposed converting government debt into shares, and its price rose dramatically as investors bought into the story of future profits.

The company’s share price eventually collapsed, ruining many shareholders and causing a political scandal in Britain. Parliamentary investigations exposed corruption and misleading promotion. The episode helped establish the South Sea Bubble as one of the classic early examples of a speculative financial mania.

It is often confused with the Mississippi Bubble, a separate 1720 crisis centered on John Law’s financial system in France. Both collapses occurred in the same year and reflected expanding credit, aggressive speculation, and unrealistic expectations.