This may have already been discussed -- I don't read all the posts -- but doesn't it seem likely that a large holder of shares (perhaps 30 million shares or more that could have been acquired long ago or perhaps taken in exchange for a service rendered or something) has instructed their broker to sell the shares for no less than a certain amount...and the market maker goes about filling that sell order throughout the day and packages them together and runs them through at the close of the market as a single exchange? If they had a large block of shares like that and want to liquidate it, It could take a month or more. The fact that there has been positive news of late has made it possible for such a seller to liquidate their position, which would have been absolutely impossible to do prior to the news because before it would have taken an entire week just to liquidate 1 million shares. Now they are able to do 5x that volume without seeing the price hurt too terribly.
All just my relatively baseless speculation -- except that there appear to me to be indications of a consistent and systematic approach to liquidate a holding.