John Blunt became the central figure in Britain's South Sea Bubble of 1720.
Blunt was a director of the South Sea Company and promoted a scheme in which the company would convert part of the British national debt into shares. Investors were attracted by rising prices and expectations of profitable trade with Spanish America, although the company's actual commercial prospects were much more limited than popular enthusiasm suggested.
Shares surged during 1720, and the company encouraged further subscriptions. As confidence collapsed later that year, prices fell rapidly, ruining many investors. Parliament investigated the episode, and several directors faced accusations of corruption.
Isaac Newton is often linked to the bubble because he invested and later lost money, but he was not its principal promoter. John Blunt's role was managerial and promotional; he was not the only person involved in the scheme or its political support.