You have $200 ready for this month's investment. A popular stock keeps climbing, and the pitch is simple: everyone who bought earlier has made money.
Earlier buyers' gains do not tell you what the business is worth at the price you face.
In London in 1720, South Sea stock quotations climbed toward £1,050, then fell to £124 by December. The business had a story people wanted to believe. The trouble was the price they paid to join it.
A story people wanted to believe
The South Sea Company was founded in 1711 to take over government debt and pursue overseas trade. Its trading rights included supplying enslaved Africans to Spanish America.
People owed money by the British government could swap that debt for company stock. The government then paid interest to the company. Shareholders expected dividends from those payments and hoped for trading profits on top.
In 1720, an expanded debt swap gave investors a fresh reason to buy. The story joined a familiar source of income — government payments — to hopes of much larger profits.
A speculative bubble develops when rising prices draw in buyers who depend increasingly on selling to someone else for more, rather than on the asset's future benefits. Their purchases push prices higher again. The rise becomes its own sales pitch.
Value is an estimate, so a fast climb alone cannot prove a bubble. A later crash is not proof either: bad business news can make an investment worth less. What matters is how well the price was supported before the bad news arrived.
The price that needed another buyer
Oxford's Newton and the Mint account records the climb and collapse. The company was years old; the price frenzy unfolded in months.
Buyers could sign up for new stock in installments, committing to a purchase while paying only part upfront. The company also lent money against its own shares. Easy funding let buyers commit more money to the boom.
When confidence weakened, sellers had to accept lower prices to find buyers. Someone relying on resale to meet a payment now had a shrinking holding and a bill that had not shrunk. A payment deadline could force a sale even if the owner wanted to wait.
After the collapse, Parliament investigated and several company directors were punished.
Suppose you paid £1,050 upfront and the same holding was worth £124 in December, excluding dividends and costs.
(124 ÷ 1,050 − 1) × 100 ≈ −88.2%.
Of the original £1,050, £926 was gone and £124 remained. A real business can still be a terrible purchase.
Five stages, seen afterward
A common version of the Minsky–Kindleberger bubble framework uses five stages. Named for economist Hyman Minsky and economic historian Charles Kindleberger, it describes recurring behavior:
These stages can overlap; the labels do not tell you when to trade. Economists Peter Temin and Hans-Joachim Voth found profitable South Sea trading in Hoare's Bank's ledgers. The bank sold some stock in the spring, before the summer peak.
A gain does not prove the seller knew the top. Profit-taking can happen while new buyers are still pushing the price up. The same sale can look like caution to the seller and opportunity to the buyer.
Identifying an unsupported price and predicting when it will fall are different jobs.
What the tulip story gets wrong
The Dutch tulip trade of the 1630s offers a warning about the stories we tell afterward. Many deals involved delivery contracts: a buyer agreed on a price while the bulb remained planted, with payment due when it could be handed over. A promised price was not money already paid.
In Tulipmania, historian Anne Goldgar used archival records to challenge the tale of a whole nation gambling away its wealth. She found a much narrower trading community, and no evidence of the nationwide financial devastation in popular retellings.
Prices did surge and break. That does not make every colorful story about the episode true. A bubble story deserves as much scrutiny as an investment pitch.
What the warning signs can tell you
The history leaves three useful questions:
- The benefit. What cash or other economic benefit supports the price? Compare the price with what ownership could deliver.
- The next buyer. How much of the case depends on somebody paying more? Herd behavior and FOMO explain why popularity can feel like proof.
- The funding. What happens if enthusiasm or credit disappears? Debt and leverage add payment commitments that survive a falling price.
Back to your $200: “profits will grow enough to justify this price” is a claim you can investigate. The evidence would be the company's results and a plausible explanation of how profits could grow.
That evidence could strengthen the case even if you dislike the crowd's enthusiasm. If it is missing, waiting for it is a complete decision. You do not have to prove that a crash is coming to pass on this opportunity.
What the price chart cannot settle is how long buyers will keep paying more. A stage label does not close that gap.
The 1929 crash takes the funding question further: borrowed money can force a sale before the owner is ready.
In short
- A convincing idea can come with an unconvincing price.
- Bubble stages organize hindsight; they do not identify a market top.
- Easy funding can fuel buying, while payment deadlines can force selling.
- A famous story is a claim to check, not evidence by itself.