Jay Cooke & Company was a U.S. bank that operated from 1861 to 1873. Headquartered in Philadelphia, Pennsylvania, with branches in New York City and Washington, D.C., the bank helped underwrite the Union Civil War effort. It was the first "wire" brokerage house, pioneering the use of telegraph messages to confirm securities transactions with clients. The bank became overextended in the building of the Northern Pacific Railway and failed, contributing to the Panic of 1873.