Here, someone put in a buy order for BTC150 at the market price. That was enough to eat up all the sell orders on the exchange and run the price up to $2200. Right now, in the middle of a trading day, if you bought BTC150 on Gemini at market, you'd take the price up about $75 to about $400. If you did that on Bitstamp, you'd take the price up by maybe $1.