The 1720 British speculative bubble involving a company granted a trade monopoly was the South Sea Bubble.
The South Sea Company received a monopoly over British trade with parts of Spanish South America in 1711. In 1720, Parliament approved a plan in which the company would assume much of the British national debt. Promotion and speculation drove its share price sharply higher, even though the company's realistic trading prospects were limited.
The price collapsed later in 1720, ruining many investors and damaging public confidence. The scandal led to investigations and accusations of corruption involving politicians and company directors. The British government reorganized the company's affairs, while the Bank of England helped manage the aftermath. The South Sea Bubble is frequently discussed alongside France's Mississippi Bubble, which also burst in 1720, but they were separate schemes. Neither event was a modern stock-market crash in the high-speed sense; both are classic examples of leveraged speculation, promotional excess, and prices becoming detached from underlying prospects.