after hours and computers thanks for advice on computer. I am on the low budget plan right now.
when you see after hours trades often you will see big volume and yet no real price movement. this means 2 institutions agreed on a price usually at EOD price and one institution wanted to lighten up on a position they do this after hours so they don't affect price during regular trading hours.
now if heavy volume and big price movement it usually is some great/bad news for an individual company.