At my office, we call after-hours stock trading "the badlands." That's because anything goes--information is unevenly disseminated, and scalpers take advantage of any angle they can muster. If you are quick, you prosper; if you are slow, you die. Casualties are high. Now both NASDAQ and the New York Stock Exchange want you to venture into those badlands. Both exchanges made it clear last week that the 4 p.m. closing bell will signify nothing come fall. The markets will stay open till 9 p.m. or 10 p.m.
The exchanges say online traders are demanding longer hours, and darned if they shouldn't...