The Bookseller of Exchange Alley
How Thomas Guy Cashed Out of the South Sea Bubble While Isaac Newton Doubled Down
A joint-stock company that possesses no profitable ships, factories, or mines can still drive its own stock price up eightfold. It only needs Parliament to grant it the right to issue new shares against rising market prices. In January 1720, the British government owed £31 million in high-interest war annuities that could not be redeemed without the bondholders' consent. Sir John Blunt, a scrivener turned director of the South Sea Company, copied John Law's Paris scheme and offered to absorb the entire national debt into South Sea shares. Under the contract approved by Parliament in April 1720, the company was authorized to issue one new share of stock for every £100 of face-value debt it retired.
That conversion rule created an accounting windfall whenever the share price climbed. If South Sea stock traded at £300, the directors only needed to hand over one-third of a share to retire £100 of sovereign debt. The remaining two-thirds of a share became surplus stock that could be sold to the public in Exchange Alley for pure cash profit. To push the stock toward £1,000, Blunt and cashier Robert Knight engineered four self-reinforcing liquidity pumps between April and August 1720:
- * Installment subscriptions: In the four money subscriptions at £300, £400, and £1,000 per share, buyers put down only ten to twenty percent in cash. That rule turned every subscription receipt into a five-to-one leveraged call option.
- * Lending on own shares: Between April and June, the company lent more than £11 million of newly raised subscription cash right back to shareholders at £250 to £400 per share. Borrowers used that company cash to bid up existing stock on the street.
- * Bribes in zero-money stock: Knight entered fictitious stock options for twenty-seven members of Parliament and royal ministers, including Chancellor of the Exchequer John Aislabie. Officials collected cash price differences without paying a shilling up front.
- * The Bubble Act squeeze: In June 1720, Blunt persuaded Parliament to outlaw rival joint-stock promotions that lacked royal charters, hoping to channel all speculative cash exclusively into South Sea shares.
One investor inside Exchange Alley understood the arithmetic of the pump from the opening bell. Veteran London bookseller Thomas Guy, the son of a Southwark lighterman, had built a fortune printing affordable English Bibles and buying discounted sailors' pay tickets. He held £54,040 of original South Sea stock acquired at roughly £120 per share. Instead of borrowing against his holdings to buy the summer subscriptions, Guy walked into Garraway's and Jonathan's coffeehouses on April 22, 1720, when the price crossed £300. Over the next seven weeks, he sold his entire position in six disciplined tranches, disposing of his final shares on June 10 at £600.
Three miles west at the Royal Mint, Sir Isaac Newton made the exact same initial calculation. Newton sold £7,000 of South Sea stock in April and doubled his money. Then he watched his friends grow rich as the price soared past £700 in June and £950 in July. Swept into the crowd, Newton re-entered the market at the top with a vastly larger sum. According to his niece's husband, Newton later lamented that he could calculate the motions of heavenly bodies to mathematical precision, but could not calculate the madness of crowds. In August, the Bubble Act starved buyers of rival shares and forced them to dump South Sea stock to meet installment calls. When the Sword Blade Bank failed in September, liquidity vanished. While Isaac Newton re-entered the market near the summer peak and lost twenty thousand pounds, Thomas Guy used his £234,000 cash profit to construct and endow Guy's Hospital in Southwark before the stock collapsed to £124.