The New York stock Exchange closes each weekday (except holidays) at 4:00 p. m. , Eastern Standard Time. There is an after-hours trading period that lasts until 8:00 p. m. , Eastern Standard Time.
The NYSE in New York opens at 9:30 am eastern standard time and closes at 4:00 pm eastern standard time. NYSE After Hours runs from 4:00 pm eastern standard time until 8:00 pm eastern standard time.
The stock market in New York effectively closes down around the end of the business day every business day of the week. If you are relying on it being open it's best to check with them.