One of the best books I've read is Fooled by Randomness by Nassim Taleb, where I learnt the difference between noise and information. So to me, variations in SP in a day is noise to me.
But when I turn on the news at 6pm, or read the paper online, it seems like everyday the market is open they make a story to rationalise and explain the movements in the market that day. For example, recently the explained a drop as being due to the Chinese New Year holiday, and now they're using the Egypt unrest story.
Why can't noise be just noise? People buy and sell everyday for various reasons. Why do we have to attribute movement to stories like these? How accurate do you think it is to do this? I mean, when I heard the Chinese New Year story, I thought it was pretty ridiculous that people would be selling their shares just because China would be taking a few days off for the holiday. I mean, really? The market reacts to things like that??