Jay Cooke & Company was a prominent American investment banking firm founded in 1868 by Jay Cooke, a financier known for his role in financing the Union Army during the American Civil War. The firm specialized in underwriting government bonds and railroad securities, playing a significant role in the expansion of the U.S. railroad system. However, the firm faced financial difficulties in 1873 due to overextension and the economic downturn known as the Panic of 1873. This led to its bankruptcy, which had a ripple effect on the financial markets and contributed to a broader economic depression in the United States.