Some people have seriously suggested shortening trading hours, on the grounds that all the interesting trading happens at the open and especially at the close, closing prices are the ones that are reported and used for risk analysis etc.. If everyone wants to trade at the close, why not just have one "opening" auction every day, and the price from that auction is the "closing" price for the day? That also eliminates the opportunity for trying to "pick off" or "front-run" other people's orders, or "quote fade" on the other side.