Why do stocks trade after hours?

[ER9]

For example sometimes I see Nasdaq stocks that will trade for an hour or so after the market closes.

 

[howardy2k]

 

[hii a_ooiioo_a]

There are electronic exchanges that trade until about 8:00 pm, and also in the morning before the 9:30 am open.

There are fewer people trading then, so the bid and ask prices are farther apart.

 

[prox]

Supposed to help out the little guy who works during the day.