The Mississippi Bubble of 1720

By Ryan O'Connell, CFA, FRM Published October 20, 2026

The Mississippi Bubble of 1720 turned an ambitious reform of France’s public finances into a stock-market and monetary crisis. John Law connected government debt, company shares, and banknotes in a system that promised cheaper financing and greater commerce. Its weakness emerged when defending the company’s share price required issuing more of the money investors were beginning to distrust.^[1]

The episode helps explain how a financial crisis can spread between institutions. Understanding it requires following three different promises: the Crown’s payments to its creditors, the company’s returns to shareholders, and the bank’s obligations to noteholders.

What Was the Mississippi Bubble?

The Mississippi Bubble was the speculative boom and collapse associated with John Law’s financial system in France, particularly during 1719–1720. The company at its center began as the Company of the West, associated with Louisiana and the Mississippi River. After absorbing other businesses, it became the Company of the Indies. Its activities expanded far beyond colonial trade into government finance, tax collection, and banking.^[1]

The documentary follows this process visually. The explanation below covers the institutions, transactions, and collapse independently.

The Fiscal Problem John Law Tried to Solve

Louis XIV died in 1715 after decades of costly wars. Economist François Velde’s reconstruction places French public debt at approximately 2.8 billion livres in September 1715. The livre was France’s unit of account: the unit in which prices and obligations were recorded. Debt reductions and other measures eased the immediate burden, but the monarchy still faced difficult financing and tax-collection problems.^[1]

Law, a Scottish financier, believed that shortages of money constrained employment and commerce. In his 1705 book Money and Trade Considered, he argued for monetary arrangements that could support more economic activity than dependence on silver allowed. His earlier Scottish proposals differed from the system eventually implemented in France, but the ambition to expand usable money and credit connected them.^[2]

The Bank Initially Built Confidence

Law founded the privately owned General Bank in May 1716. Its notes promised payment in specified silver coin. Government measures helped their circulation, including explicit acceptance for individual tax payments in 1717. When the Crown nationalized the bank as the Royal Bank in December 1718, Velde reports approximately 39.5 million livres of notes circulating at par.^[1]

That beginning matters. Notes offered convenience and a credible payment promise before the later expansion of the System. The subsequent crisis therefore needs an explanation of how those promises changed and became entangled with the company’s shares.

What the Mississippi Company Actually Did

The Company of the West received its Louisiana charter in 1717. By 1719, Law’s enterprise had combined businesses associated with the East Indies, China, and Senegal, among others. These acquisitions brought commercial privileges and operating assets into the enlarged Company of the Indies.^{[3] [4]}

The company also acquired the operation of the royal mints and major tax-collection rights. Under a tax-farming arrangement, a collector agreed to pay the Crown a specified amount and undertook the collection work. Gross tax receipts were consequently different from the collector’s profit: payments to the Crown and operating costs still had to be met.^[1]

These were substantial economic activities. They also carried human consequences. The Senegal acquisition connected the enterprise to the Atlantic slave trade, and its Louisiana operations involved enslaved Africans. The company’s colonial business cannot be understood solely as a financial asset on a Paris balance sheet.^[3]

Institutional boundaries narrowed further in early 1720. Law became controller-general of finances on January 5, and the Royal Bank was brought into the company in February. The Crown, bank, and company remained distinguishable institutions, but their management, financing, and obligations increasingly overlapped.^[1]

How French Government Debt Became Company Equity

The central financial operation was a conversion of government claims into claims on the company. Its mechanics involved several connected transactions:^[1]

1. The company financed the Crown. The Crown owed the company an annual payment on the resulting loan.
2. The Crown called eligible old debts for repayment. Creditors received reimbursement claims payable through the company.
3. Creditors could subscribe for company shares. Treasury reimbursement claims became a means of paying for subscriptions.
4. Shareholders depended on company income. State payments and profits from commercial and fiscal privileges would support shareholder returns.

The distinction between repayment and reinvestment is essential. The Crown could compel reimbursement of eligible debts under their terms; becoming a shareholder was a separate choice. Rising share prices encouraged creditors to make that choice.

The conversion changed who held the government’s obligations and what former creditors might own. A fixed government claim could become equity whose value depended on company earnings, political privileges, and investors’ willingness to hold the shares.

Why Share Subscriptions Amplified the Boom

New issues encouraged demand for older shares. The original shares became known as mothers, followed by daughters and granddaughters. To subscribe for one granddaughter, an investor needed four mothers and one daughter. That requirement linked access to a new issue with ownership of existing shares.^[1]

Installment subscriptions added another incentive. Subscribers could obtain exposure by paying part of the price initially. If they stopped paying, they forfeited their subscription and the installments already paid. This gave the certificates option-like economics and could magnify the sensitivity of the subscriber’s investment to the share price. It illustrates a form of financial leverage without requiring an ordinary margin loan.

The price movement was enormous, although early quotations and different instruments are difficult to compare precisely. Shares quoted around 500 livres in May 1719 reached approximately 10,000 around late 1719 and early 1720. Using those approximate quotations, 10,000 / 500 = 20 times. That nominal price comparison excludes dividends, payment timing, and changes in the value of money; it is not a realized investment return.^[1]

A rising quotation also did not establish intrinsic value. Company intervention increasingly influenced the price investors observed.

How Share-Price Support Put Pressure on Banknotes

The company supported its shares through purchases financed with banknotes. When investors sold shares into that support, they exchanged an equity investment for money. If additional notes financed those purchases, defending the share price enlarged the bank’s monetary obligations. Velde identifies this relationship as central to the System’s failure.^[1]

This is the relevant connection to money creation: selling pressure could be absorbed through additional monetary liabilities. The transaction did not itself produce more goods, trading profits, or tax revenue.

Between March 5 and May 31, this measure increased by 2,235.1 − 1,089.9 = 1,145.2 million livres. Its growth was (2,235.1 / 1,089.9 − 1) × 100 = approximately 105.1%. The figures use one accounting definition; they do not measure purchasing power or every component of money in France.^[1]

Policy also restricted alternatives to notes. A February 27, 1720 measure limited gold and silver coin holdings to 500 livres and required payments above 100 livres to use notes. Such measures attempted to sustain demand for paper while the System’s liabilities expanded. Pressure appeared in foreign exchange and domestic prices, although these measures of money’s value did not move identically.^[1]

A note’s face amount could remain unchanged while its purchasing power deteriorated. That distinction between nominal amounts and inflation is necessary when interpreting both the share boom and the losses.

The 1720 Collapse and the May Decree

Withdrawing support threatened the shares and the appeal of the debt conversion. Maintaining a high support price increased pressure on the notes. Policy repeatedly changed direction as the authorities tried to manage these connected problems.^[1]

Velde supplies the financial chronology; contemporary accounts by Mathieu Marais and Edmond Barbier corroborate the May reversal, and Marais records the July suspension and the October decree ending ordinary note payments from November.^{[1] [5] [6]}

The reversal came six days after the decree, but could not erase the uncertainty it had exposed. Marais’s contemporary account describes the withdrawal of the measure without a recovery of confidence.^[5]

What Survived the Collapse?

The cleanup involved a liquidation known as the Visa. Holders submitted instruments and information about how they had acquired them. Accepted claims were converted into public annuities—rights to streams of government payments—under rules that imposed different reductions. Unsubmitted instruments became worthless. Claims of 500 livres or less escaped nominal reduction, but that treatment did not guarantee immediate cash or preserved purchasing power.^[1]

Velde concludes that the aggregate public-debt burden was eventually restored broadly near its earlier level. That aggregate comparison does not describe each person’s experience. Investors held different instruments, entered at different prices, and faced different liquidation outcomes.^[1]

The company also survived in reorganized form. Its ships, commercial activities, and privileges gave it an operating business after the monetary System failed. Jaucourt’s eighteenth-century Encyclopédie entry describes the continuing enterprise, while the Historic New Orleans Collection documents its reorganization. Its Indian trading monopoly was withdrawn in 1769.^{[7] [3] [4]}

Mississippi Bubble vs. South Sea Bubble

Both episodes connected government debt, privileged companies, and speculative share prices. They occurred in the same period, but involved different countries and institutions.^{[1] [8]}

Common Mistakes When Explaining the Mississippi Bubble

• Treating the company as an imaginary business. It had operating assets and privileges; their existence did not justify every share price.
• Collapsing shares and notes into one instrument. Equity ownership and a bank’s monetary obligations created different claims.
• Calling debt reimbursement a compulsory stock purchase. Repayment and subscription were separate transactions.
• Reading a small installment as the full share price. Further payments were required to complete the subscription.
• Calling every published monetary amount circulation. Authorized issuance, notes issued less notes burned, and money’s market value are different measures.
• Treating the May decree as a completed, uniform haircut. Its proposed reductions differed, included an exception, and were revoked.

What the Evidence Can—and Cannot—Show

Some prices are approximate, instruments changed, and official intervention affected quotations. Velde’s valuation exercise estimates peak overvaluation by a factor of roughly two to five, depending on assumptions. That is a historical valuation judgment, not a precisely observed fundamental price.^[1]

The useful lesson concerns credibility: identify which institution owes what, how it finances that promise, and whether protecting one obligation weakens another. Modern discussions of central-bank credibility and independence address related institutional questions, but Law’s combined roles and royal privileges require their own historical explanation.

Sources

Sources consulted October 20, 2026. Historical quotations and reconstructed totals should be read with the qualifications above. Calculations are shown in the text.

1. François R. Velde, Government Equity and Money: John Law’s System in 1720 France, Federal Reserve Bank of Chicago Working Paper 2003-31, November 30, 2003. Especially §§2.5–3.3, 4.3–6.3, 7.1, and 8.2–8.5; Tables 2–4. A modern historical reconstruction and valuation analysis.
2. John Law, Money and Trade Considered, 1705, Yale Law School’s Avalon Project transcription. Especially Chapters 2 and 5.
3. Erin M. Greenwald, The Rise and Fall of John Law, Historic New Orleans Collection, September 1, 2026. Company origins, acquisitions, colonial operations, and reorganization.
4. Bibliothèque nationale de France, Compagnie des Indes authority record, FRBNF12492161. Institutional combination and subsequent monopoly history.
5. Mathieu Marais, Journal et mémoires, April–December 1720, volume 1, edited by Adolphe de Lescure, Firmin-Didot, 1863; Wikisource transcription. June discussion of the May reversal, July 17 ordinance, and October 12 account of the October 10 decree.
6. Edmond Jean François Barbier, Chronique de la régence et du règne de Louis XV, May 1720, Charpentier edition, 1858, volume 1, pp. 34–37; Wikisource transcription. Contemporary account, including the May 27 reversal.
7. Jaucourt, Indes, Compagnie Françoise des, Encyclopédie, first-edition text, volume 8, pp. 662–664; Wikisource transcription. Eighteenth-century retrospective account of the continuing company.
8. Bank of England, History, updated December 9, 2024. Section on the South Sea Bubble of 1720.