On May 26, 1896, the coronation of Czar Nicholas II was held in Moscow, and Charles Henry Dow published an index of industrial stocks for the first time in New York.
The index, known as the Dow Jones industrial average, has changed many times since 1896, when it was made up of 12 companies. It now numbers 30. On Wednesday, it broke 20,000 for the first time.
Here's a list of milestones in the marquis stock index.