Trading Day.

In plain English

A trading day is any day the stock exchanges are open, which in the US means weekdays that are not market holidays. Regular trading runs from 9:30 a.m. to 4 p.m. Eastern, though limited trading happens before and after in extended hours. Weekends and roughly nine holidays a year are not trading days, so orders placed then execute when the market next opens. The count of trading days matters for things like how quickly a trade settles and how returns are measured.

01Why it matters

Knowing which days are trading days tells you when your orders will actually execute and why a trade placed on Friday night does not fill until Monday.

02The math, step by step

You place a stock order at 8 p.m. on Friday. Because the weekend is not a trading day, the order waits and executes when the market reopens Monday morning.

03What this is NOT