What was the name of the 1720 speculation-driven collapse involving the South Sea Company?

The 1720 speculation-driven collapse involving the South Sea Company was the South Sea Bubble.

The South Sea Company received a monopoly over British trade with Spanish South America and assumed part of the British government’s debt. Its shares rose dramatically in 1720 as investors expected enormous profits, even though the company’s realistic trading prospects were far more limited than the excitement suggested. When confidence broke, the share price collapsed.

The episode became one of Britain’s best-known financial bubbles. It damaged investors, provoked a political scandal, and led to investigations of company directors and officials. The South Sea Bubble occurred long before modern stock exchanges and electronic trading, but it displayed familiar crash dynamics: promotional claims, rising prices, imitation buying, leverage, and sudden loss of confidence. It is often discussed alongside the Mississippi Bubble in France, another major financial collapse of the same era.