Quote from JRL:
I've been following a stock this week (MGM), and there seems to consistently be huge movements in after-hours trading. Just happened now, 10 minutes after the day's closing, the price gapped up from $10.37 - $10.81.
All I've heard about after-hours stuff is that it's typically only played by seasoned pros. What exactly drives all the price movements? Especially in MGM, this week, the pattern appears to be big gaps up when the market closes, maybe big gaps up the following morning, but then a big reversal.
What drives the after-hours activity?