I've never understood this impulse to try and divine a market's reaction to news from a 1-day timespan. Especially for move like this, where the effects in corporate governance might not be seen for some time, wouldn't the better indicator of how well-received it is be the stock price after 3, 6, 12 months? Aren't these just big fund managers making snap judgments and moving sums around for the biggest bang?
Actually, more likely it's a few hundred different automated trading systems all playing off each other. If you're managing a pension fund, volatility is the last thing you're after.
Apple went down about the same amount, so it was probably something else...