Which 1720 British company’s share collapse became a landmark early stock-market crash?

The South Sea Company’s share collapse became a landmark early stock-market crash in 1720.

The South Sea Company was granted a monopoly over British trade with parts of Spanish South America and became associated with a government debt-conversion scheme. Its shares rose spectacularly as investors were encouraged by promotion, speculation, and expectations about future profits. The price then collapsed later in 1720, ruining many investors and damaging confidence in joint-stock companies.

The episode is called the South Sea Bubble, but it occurred alongside the collapse of John Law’s Mississippi Company scheme in France. Those were connected examples of speculative excess, not the same company or market. Parliament investigated the South Sea affair, and prominent figures were implicated in the controversy. The crash is historically important because it showed that organized securities markets could experience extreme bubbles long before modern exchanges and electronic trading existed.