Stock Markets Exposed - What is the open and close time of US stock markets?

What is the open and close time of US stock markets?

What time US stock market open and close? does it open on sunday and saturdays unlike indian market which observe holidays on SAT & SUN

Officially opens at 9:30 AM Eastern and closes at 4 PM. Not open Sat and Sunday, along with a short list of holiday's. You can find those holiday's at nyse.com. Having said that, there is after and before market trading in a variety of stocks that occurs off the exchange.
The New York Stock Exchange and NASDAQ markets are open Monday through Friday from 9:30 until 16:00 (4 p.m.) Eastern time. They are not open on Saturdays and Sundays, and they are closed on workdays that are legal holidays.
Trading hours are from 9:30 a.m. to 4:00 p.m. E.S.T. M-F