Why was jay Gould of Union Pacific railroad known for doing.?

Jay Gould was a railroad speculator, generally known for being particularly ruthless. He is though known and remembered by what was called as "Black Friday"; this was in August of 1869 when he started to buy gold trying to corner the market. These speculations ended by September 24 of the same year, called "Black Friday" because of the panic caused as the price of gold fell dramatically.

He was a leading American railroad developer and speculator. He became very rich off of the railroad business.