Today’s a half day for the market, and it got me thing. The market often moves the most pre-market or in the first few hours of the day, so why do we need a full day of trading?

On a normal trading day the market is open from 9:30am-4pm EST. Could the market operate the same if it close at 1pm? This is just a thought experiment.

My guess is it would increase volatility during those hours, and traders would start to use pre/post market trading windows more often.