What was the name of the speculative bubble that burst in Britain in 1720?

The speculative bubble that burst in Britain in 1720 was the South Sea Bubble.

The South Sea Company received trading privileges and assumed part of the British government debt. Its shares surged as investors expected enormous commercial profits and were attracted by aggressive promotion. The company’s actual trade prospects did not justify the prices, and confidence collapsed later in 1720.

The resulting crash ruined many investors and triggered political scandal in Britain. Parliament investigated the company’s directors and alleged corruption. The episode is often discussed alongside France’s Mississippi Bubble, which also collapsed in 1720, but the two schemes were separate. South Sea shares were not ordinary shares in a broad modern stock index; they represented a highly concentrated company speculation linked to public debt.