The bankruptcy of which company initiated the Panic of 1873?

The bankruptcy of Jay Cooke & Company, a prominent bank in the U.S., initiated the Panic of 1837. Jay Cooke & Company had been a major financial backer of the Union in the Civil War and financed the westward expansion of the transcontinental railroad. One of their major undertakings was to finance the Northern Pacific Railway, which overextended their reserves and caused investors to withdraw money from the company, leading to Jay Cooke & Company declaring bankruptcy in 1873.