the speculation mania that ruined many British investors in 1720. The bubble, or hoax, centred on the fortunes of the South Sea Company, founded in 1711 to trade (mainly in slaves) with Spanish America, on the assumption that the War of the Spanish Succession, then drawing to a close, would end with a treaty permitting such trade. The company's stock, with a guaranteed interest of 6 percent, sold well, but the relevant peace treaty, the Treaty of Utrecht made with Spain in 1713, was less favourable than had been hoped, imposing an annual tax on imported slaves and allowing the company to send only one ship each year for general trade. The success of the first voyage in 1717 was only moderate, but King George I of Great Britain became governor of the company in 1718, creating confidence in the enterprise, which was soon paying 100 percent interest.

In 1720 there was an incredible boom in South Sea stock, as a result of the company's proposal, accepted by Parliament, to take over the national debt. The company expected to recoup itself from expanding trade, but chiefly from the foreseen rise in the value of its shares. These did, indeed, rise dramatically, from 128 ¹/₂ in January 1720 to more than 1,000 in August. Those unable to buy South Sea stock were inveigled by overly optimistic company promoters or downright swindlers into unwise investments. By September the market had collapsed, and by December South Sea shares were down to 124, dragging other, including government, stock with them. Many investors were ruined, and the House of Commons ordered an inquiry, which showed that at least three ministers had accepted bribes and speculated. Many of the company's directors were disgraced. The scandal brought Robert Walpole (Walpole, Robert, 1st earl of Orford), generally considered to be the first British prime minister, to power. He promised to seek out all those responsible for the scandal, but in the end he sacrificed only some of those involved in order to preserve the reputations of the government's leaders. The South Sea Company itself survived until 1853, having sold most of its rights to the Spanish government in 1750.