Which 1720 British speculative bubble is one of the earliest major stock-market crashes?

The South Sea Bubble was a major British speculative crash that collapsed in 1720.

The South Sea Company received a government-backed monopoly over trade with Spanish South America, although its actual commercial prospects were far less impressive than popular expectations. Its shares rose spectacularly as investors bought into promotional claims and easy-credit speculation.

The company’s stock peaked in 1720 before collapsing later that year. The crash ruined many investors and damaged public confidence, while Parliament investigated the company's directors and associated corruption.

The South Sea Bubble occurred alongside the French Mississippi Bubble, making 1720 a landmark year in financial history. It is often used as an early example of how monopoly claims, leverage, herd behavior, and unrealistic expectations can inflate asset prices.