Apple Inc (AAPL)

[ASimEE]

After hours trades can also be delayed postings of large orders that were filled during the day.

If I was trying to buy $90MM worth of a stock, I wouldn't want it broadcast throughout the day because it could start a stock rally before my lot was filled at the price I wanted.

The investor can tell his broker he wants X amount of shares at an average price of X, and the market maker can fill that order throughout the day without posting it to the ticker until after hours. This helps the market maker fill the order at the correct price and keeps people from reacting (positively or negatively) to seeing all the trades going through.

Note this can be done for a long or short position.