IMHO, we are seeing a short term (and I must emphasize that I beleive it to be only a very short term phenomenon) decrease in share price because:

1) some people will always sell on news. They have waited for the news and they hope to get out at a higher price, when the price slips they get desparate and decide to sell at any price, since they were only in it for the short term anyways

2) I have not seen any research out yet. We will see a lot of research reports out in the next 24 hours. Many non-technical retail investors will not be able to grasp the importance of the PR and without any analysts reporting as of yet, they look at the price (which is fallling) and figure that the PR must be bad news, even though it is exactly the opposite.

3) traders will take advantage of any weakness in a stock to shake the tree and buy some cheap shares.

This will turn around and IMHO it will turn within the next 48 hours.