A precursor to the euro: the European Exchange Rate Mechanism
Before the euro existed, the countries of the European Economic Community tried to coordinate their currencies through the Exchange Rate Mechanism (ERM), a system in which each currency had to stay within a narrow band against the others, with the German mark as the de facto anchor. The goal was the same one the euro would later pursue: reducing exchange-rate uncertainty to boost trade within Europe.
The United Kingdom joined the ERM in 1990, pegging the pound to an exchange rate against the German mark that, as the years passed, became increasingly hard to sustain. It's the same structural problem we already saw with the gold standard and Bretton Woods: when a fixed exchange rate stops reflecting a country's economic reality, something eventually has to give.
Why the pound was doomed: an economy and a policy pulling in opposite directions
In the early 1990s, the United Kingdom was going through a recession with high unemployment, the classic recipe for a central bank wanting to cut interest rates and stimulate the economy. But Germany, in the middle of reunification after the fall of the Berlin Wall, needed high interest rates to control the inflation generated by massive spending in the former East Germany.
The United Kingdom, tied to the mark through the ERM, was forced to keep interest rates high (above 10%) to defend the pound's exchange rate, exactly the opposite of what its domestic economy needed. Several investors, Soros among them, concluded that this contradiction was unsustainable: sooner or later, the United Kingdom would have to choose between its economy and its exchange rate.
- Germany needed high rates to curb reunification-driven inflation.
- The United Kingdom needed low rates to climb out of recession.
- The ERM forced the pound to track the mark, not the British economy.
- The Bank of England's currency reserves were finite; the market's capacity to sell pounds, practically wasn't.
The bet: $10 billion against a government's promise
George Soros's Quantum Fund, along with other major speculators who spotted the same crack, built a massive short position against the pound: it borrowed pounds, sold them for German marks and other currencies, betting it could buy them back much cheaper later. Soros's position is estimated to have reached $10 billion, a colossal figure for the time.
imagine you borrow 100 pounds when they trade at 3 marks each and sell them immediately, getting 300 marks. If the pound devalues to 2.5 marks, you can buy back 100 pounds spending only 250 marks, repay the loan, and keep 50 marks in profit. The bigger the position and the bigger the devaluation, the bigger the profit: at a scale of $10 billion, a devaluation of around 15% translated into a profit of roughly $1 billion.
September 16, 1992: the day the Bank of England gave up
That morning, the Bank of England intervened, buying billions of pounds with its currency reserves to prop up its exchange rate. At midday, facing selling pressure that wouldn't let up, it raised its reference interest rate from 10% to 12% in a desperate attempt to make holding pounds more attractive. That afternoon it announced a second hike, to 15%, which never actually took effect.
At 7 p.m. that same evening, the British government admitted defeat: the pound would be pulled out of the Exchange Rate Mechanism and would start floating freely on the markets. The direct cost to British taxpayers was estimated at around £3.3 billion, mainly from losses on pound purchases made at a price that, hours later, no longer made any sense.
'The man who broke the Bank of England'
The British press gave Soros that nickname, which has stuck to this day. It's a simplification (several funds were betting in the same direction, and the underlying problem was the exchange rate's own unsustainability, not a single speculator), but it captures a real idea well: no central bank, however large its reserves, can indefinitely defend a price that economic fundamentals no longer support.
It's the same lesson, in different clothes, that we already saw with the end of the gold standard and the 1971 'Nixon Shock': a fixed exchange rate commitment only lasts as long as it's credible that the country defending it has both the will and the resources to sustain it against any pressure. Once markets stop believing that, defending it becomes extraordinarily expensive and, almost always, futile.
What this story teaches us about risk, conviction, and leverage
Beyond the anecdote, Black Wednesday illustrates a pattern that repeats across several of the great bets in this series: spotting an unsustainable contradiction between what a price says and what economic reality suggests, having the conviction to hold the position under pressure, and having enough capital (and leverage) that a relatively modest price move translates into an extraordinary gain.
For an individual investor, the practical lesson isn't 'try to find the next overvalued pound': concentrated, heavily leveraged macro bets of this kind are among the riskiest ways to invest that exist, and the vast majority of people who attempt them lose money. The lesson is understanding why they work when they do: the gap between what something is priced at and what its fundamentals justify can't hold forever, whether the price in question is a currency, a stock, or a speculative asset.
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Frequently Asked Questions
The most commonly cited figures put the Quantum Fund's total profit from the operation at around $1 billion, though the exact number varies somewhat depending on the source and the exact period counted.
No. Shorting a currency within a floating or semi-fixed exchange rate system is a legal market operation, available in theory to any investor with access to the currency markets and the necessary capital.
It was a system, a precursor to the euro, in which the currencies of several European Economic Community countries had to stay within a narrow fluctuation band against each other, with the German mark as the main reference.
Because of the nickname the press gave him after Black Wednesday, though it simplifies reality: the underlying problem was the unsustainability of the fixed exchange rate itself, and several funds were betting in the same direction as Soros.
It's less likely among major floating-rate currencies like the dollar or the euro, precisely because they don't defend any fixed parity. The risk remains real for countries that keep their exchange rate fixed or semi-fixed against another currency when their domestic economy diverges from that reference.