Getty Images TD Ameritrade extends trading hours on select names.It’s sometimes referred to as the Wild West period of the trading day for its volatility, but extended-hours trading is about to get longer on at least one platform. Online broker TD Ameritrade is set to offer its retail clients the ability to trade 24 hours a day, five days a week — a move which is likely to be followed by rivals. Regular trading hours on the New York Stock Exchange, Nasdaq and other exchanges run from 9:30 a.m. to 4 p.m. Eastern, but the stock market is also open during extended periods, from 4 p.m. to 8 p.m., and during premarket hours, from 4 a.m. to 9:30 a.m. TD Ameritrade AMTD, +0.38% said it wants to close the gap between regular hours and extended hours for qualified investors, starting from 8 p.m. Eastern on Sunday to 8 p.m. Friday. The move also is an attempt to grow its business in Asia.via