Black Friday

The first scandal to taint the Grant administration was Black Friday, a gold-speculation financial crisis in September 1869, set up by Wall Street manipulators Jay Gould and James Fisk. They tried to corner the gold market and tricked Grant into preventing his Treasury Secretary from stopping the fraud. However, Grant eventually released large amounts of gold back onto the market, causing a large-scale financial crisis for many gold investors. Gould had already prepared and quietly sold out while Fisk denied many agreements and hired thugs to intimidate his creditors.

http://en.wikipedia.org/wiki/Ulysses_S._Grant