What event in May 1873 is commonly identified as the opening shock of the Long Depression?

The Vienna Stock Exchange crash in May 1873 is commonly identified as the opening shock of the Long Depression.

A speculative boom had developed in Austria-Hungary, especially after economic expansion and railway investment encouraged heavy share buying. On May 9, 1873, confidence broke at the Vienna Stock Exchange, producing a sharp collapse in securities prices. The day became known as the Gründerkrach, or founders’ crash.

Financial stress then spread internationally. The United States experienced a major panic later in 1873, after the failure of Jay Cooke & Company in September. Bank failures, falling investment, deflation, and weak demand contributed to a prolonged period of economic difficulty across several industrial economies.

Historians debate the exact boundaries and causes of the Long Depression, and the term can refer to different periods depending on the country. The Vienna crash is therefore best described as a major opening shock rather than the sole cause. It also should not be confused with the separate 1873 United States panic.