What was the nickname of the 1720 collapse linked to the South Sea Company?

The 1720 collapse linked to the South Sea Company was called the South Sea Bubble.

The South Sea Company was granted a British monopoly over trade with parts of Spanish South America, although its realistic trading prospects were limited. Investors became fascinated by its shares, and the price rose dramatically during 1720.

Speculation spread beyond the company itself. Parliament passed the Bubble Act in June 1720, restricting unchartered joint-stock companies, while promoters and imitators attracted money from the public. By late summer, confidence broke and South Sea shares plunged.

The episode ruined many investors and damaged the reputation of joint-stock speculation. It occurred alongside the Mississippi Bubble in France, but the two were separate schemes. The South Sea Bubble is an early example of a major speculative boom followed by a market collapse.