Stocks: After Hours

By the time you read this introduction to after-hours trading, it may be outdated.

That's because after-hours trading -- meaning the period outside the regular trading session, which runs weekdays from 9:30 a.m. Eastern time to 4:00 p.m. -- is rapidly evolving as the market tries to keep pace with technological advances and the demands of investors. Technology has come a long way from the days when the major markets closed every Wednesday so the exchanges could tally their transactions, and it is now helping push the market toward potentially a 24-hour, nonstop trading day.

The major stock markets, such as the New York Stock Exchange and the Nasdaq Stock Market, have mulled over extending their regular trading hours. But until they do, there are a host of electronics trading networks that will let you continue to trade until as late as 8 p.m.. ...