Bubbles & Manias

A speculative bubble is not a mistake about price. It is a well-functioning market operating on the wrong question — asking not "what is this worth" but "what will someone else pay for it next week". Once enough participants start asking the second question, the first one goes quiet, and the chart stops reflecting anything the instrument can support on its own cash flows.

The episodes in this hub span four centuries and almost every asset class that has ever existed. Tulip mania in 1637 ran on a futures market for flowers that had not yet bloomed. The South Sea Bubble and the Mississippi Bubble of 1720 ran on government debt reimagined as equity. Railway Mania in the 1840s ran on infrastructure that genuinely did transform the economy, but whose valuations ran several decades ahead of the cash. The Japanese asset bubble of the late 1980s ran on the collateral value of Tokyo real estate priced at levels that required perpetual borrowing against itself. The dot-com bubble ran on a technology that did reshape the world, but on companies that mostly did not survive to see it.

The common structure is tedious to describe and difficult to avoid. Credit becomes easier. A genuinely new thing appears. Price rises faster than earnings. The marginal buyer stops asking about intrinsic value and starts asking about the next buyer. Story replaces cash flow as the organising frame. Then something — a tighter central bank, a prominent failure, a ship that doesn't come in — forces the question back, and the correction is proportional to the distance travelled.

What this topic covers

• What actually rose in price, and why that specific asset
• Who supplied the credit that made the expansion possible
• How the break happened — the specific event that forced the repricing
• What the survivors took away from the wreckage

A timeline of the canonical bubbles

The mechanics that recur

Every bubble in the hub features four ingredients in some combination. First: an expansion of credit, whether through goldsmith deposit notes (1720), country-bank paper (1825), call money (1929), zaitech borrowing (1989), or fibre-optic vendor financing (1999). Second: a genuinely new asset class or technology — paper money, joint-stock companies, public-domain railroads, internet platforms. Third: a story compelling enough that valuation models stop being run because the run is itself the strategy. Fourth: a marginal buyer increasingly funded by leverage, so that a small price reversal compounds into forced selling.

The break tends to come from outside the bubble itself. The Bank of England's 1825 rate hike triggered the Latin American collapse. The Bank of Japan's 1989 tightening punctured the Nikkei. The Federal Reserve's 1999–2000 policy turn ended the Nasdaq run. In each case the break was small and specific, and the cascade that followed was not — because the credit that had funded the expansion needed continuous appreciation just to service itself.

Key figures

• John Law — Scottish gambler turned French Controller-General; the architect of the Mississippi Bubble; see also the John Law biography
• Gregor MacGregor — invented the Latin American republic of Poyais and sold its bonds in London during the Panic of 1825
• George Hudson — the "Railway King" of the 1840s Railway Mania
• Jesse Livermore — front-ran several manias; see the Boy Plunger biography
• Alan Greenspan — coined "irrational exuberance" in 1996; presided over the dot-com bubble

Modern parallels

The cryptocurrency cycles of 2017 and 2021, the SPAC boom of 2020–2021, and the meme-stock episode of January 2021 each tracked the four-ingredient pattern with little variation. The asset was new (or new-feeling). Credit was abundant — zero rates, retail margin, leveraged ETF wrappers. The story was that traditional valuation no longer applied. And the marginal buyer was increasingly leveraged or had a cost basis that depended on continuous appreciation. None of those episodes are in this hub yet, but the structural reading is the same.

Start here

• Tulip Mania — the template, though not quite the caricature
• The South Sea Bubble — government debt financialised
• The Dot-com Bubble — the modern canonical case

A useful long pairing: read the Mississippi Bubble and the South Sea Bubble together. They were contemporaneous, drew on the same financial innovations, and broke in the same year — and the comparison clarifies which features of each bubble were specific to its country and which were specific to the underlying mechanics.