The 1873 event that began with a Vienna stock-exchange crash and helped start the Long Depression was the Panic of 1873.
The crisis followed years of railway speculation and rapid investment in Europe and North America. On May 9, 1873, the Vienna Stock Exchange crashed, undermining confidence in heavily leveraged banks and companies. Financial stress then spread to other markets, including Germany and the United States.
In the United States, the collapse of the banking firm Jay Cooke & Company in September 1873 contributed to a major panic. The New York Stock Exchange temporarily closed for the first time in its history, from September 20 to September 29.
The resulting downturn is commonly called the Long Depression. Its length and severity varied by country, and historians distinguish it from the Great Depression of the 1930s.