Black Friday in the Vienna Stock Exchange crash of 1873 occurred on May 9, 1873.
The Vienna exchange collapsed after a speculative boom in property and railway companies. Investors had bought shares at rapidly rising prices, encouraged by easy credit and confidence following Austria-Hungary's economic expansion. When doubts about company values grew, selling accelerated and prices fell sharply.
The Vienna crash became an important early signal of the international Panic of 1873. Financial stress soon reached Germany and the United States, where the failure of the banking firm Jay Cooke & Company in September helped trigger a major American panic. The downturn contributed to a long period of weak growth often called the Long Depression.
The date can be confused with the American events of 1873 because the crisis crossed borders. “Black Friday” here specifically refers to the Vienna exchange disaster on May 9, not to the later U.S. stock-market tradition associated with other dates.