Apple (AAPL.US) Unexpectedly Dropped on Rebalancing Day, Who's to Blame

Apple AAPL was set to be a big winner in the quarterly index rebalancing last Friday, as the wave of index fund rebalancing was expected to boost its stock price. Indeed, it was mostly so for most of the day, but then things changed in the last 10 minutes before the close. Apple quickly fell more than 2% from its intraday high to finish in the red, surprising market observers who speculated on what triggered the change.