Apple Closed at Exactly 500.00 per Share Last Friday

Apple (AAPL) closed at exactly 500.00 per share last Friday, not 500.37, no 499.98, but exactly 500.00, with the four zeros. What's up with that?

Maybe because it was options expiration day? Do you know the chances of a stock closing the day with four zeros, assuming it closes at 1000 per share or less? The chances are one in ten thousand.