Factoring cash into share prices is fine if you're in Econ 101 or you're Warren Buffet, but in practice stocks usually go up when they announce an increase in expectations in dividend payouts. At some point the market does not trust firms to manage their extra cash to line shareholders' pockets rather than their own, and beyond that point the market wants to see dividends paid out.
My understanding is that the stock price is actually adjusted downward by the per/share dividend on the ex-dividend date. For regular small dividends this change is not really noticible in the noise of regular trading but for large/special dividends it is.
You can see that the difference between the close on Nov 12 and the open on Nov 15 is $2.63 where the difference in the surrounding days in about 20 times less.
