The Panic of 1873
A building and railway boom, fed by French war reparations flooding into Germany and Austria, broke first in Vienna in May, then reached New York in September when the bank financing the Northern Pacific Railway failed. The New York Stock Exchange closed for ten days. What followed ran for years on both sides of the Atlantic and was called the Great Depression until a worse one took the name. It was the first crisis to move between continents at the speed of the telegraph — a fully synchronized global panic.
A speculative belief detaches asset prices from fundamentals; the belief breaks and prices collapse.