Stanley Druckenmiller spent the 1980s building Duquesne Capital and the 1990s as the lead portfolio manager at Soros Fund Management, where he co-managed the Quantum Fund alongside George Soros. The September 1992 short of the British pound — known as Black Wednesday in the U.K.

(per Bank of England historical archives at bankofengland.co.uk/historical-archive and U.

K. Treasury historical accounts) — produced approximately $1 billion of profit on a position size that was reportedly far larger than any other Quantum Fund position at the time. The trade was a clean illustration of what Druckenmiller has discussed across multiple public interviews and talks (Bloomberg, CNBC, Norges Bank Investment Management presentations, university lectures, and other public-domain venues; bibliographic citation only): when the payoff is asymmetric, swing the bat.

The trade's setup: the British pound was committed to staying within the Exchange Rate Mechanism (ERM, the European pre-euro currency-pegging arrangement), but U.K. economic conditions could not sustain the implied exchange rate; the Bank of England would need to either devalue (yielding large profit on a short pound position) or defend the peg through extreme rate hikes (limiting further pound downside).