New York Gold Exchange

The New York Gold Exchange was a New York City-based market for trading in gold, incorporated in 1864 by James Boorman Colgate to facilitate gold speculation that was restricted on the New York Stock Exchange during the Civil War. From 1866, transactions of the exchange were settled through the New York Gold Exchange Bank, and from 1878 through the Bank of the State of New York.

Background
Prior to the incorporation of the exchange, gold speculators on Wall Street during the first years of the U.S. Civil War conducted their trading through an informal street market on William Street, near Exchange Place, and also at Gilpin's News Room, on the southeast corner of William and Exchange. These street traders sought to profit from the decrease in the value of Demand Notes and Legal Tender Notes (a.k.a. United States Notes), the paper monies issued by the United States Federal government during the war (both being referred to colloquially as greenbacks), against the price of gold, or vice-versa, an activity that was lucrative enough to sustain a formal exchange by 1864, despite protestations that such speculation was unpatriotic.

Post-War Era (1865-1869)
Following defeat of the Confederacy, the New York Gold Exchange became part of the New York Stock Exchange.

Black Friday (1869)
An attempt by Jay Gould and his partners, the Gold Ring conspirators, to corner the American gold market took place primarily on the exchange during the trading hours of 24 September 1869, an event that saw the price of gold spike from $145 USD to $162.5 (+11.38%) before falling to $133 (-19.96%) by the end of the day. The volatility spread across the market in the days that followed, causing a national financial panic.