I think your probably 1/2 right MJ. I see this in too many stocks now. Its a great way for the big MM to pad their funds at the expense of the small guy who has "no" inside information. I know that noone is supposed to have inside info, but I'm sure the big guys have the money to get whatever they need to get in the investment world.
There is a natural tendancy for people to take profits as well.. some have preset ranges (ie: 10 or 20% gain then boom.. sell and call it a day for that investment and move on). I do agree with some of the posters here that the MM are trying to hit the sell stops and get in lower. It's not like we can't all do it.. I just think we have to do it sooo blindly that it just makes no real sense to contemplate it.
I guess that's all I've been pushing... if you can afford to hold.. hold and don't try to buy on rumor and sell on news.. the news may surprise the market while your out of it after making a small profit..or even a loss. It's happened to me and I know it can be tempting to take the some profit and wait for the big dip. I like to have a good run and take a little off the table, keeping it for a rainy day.. but not to play it back into the same investment. It becomes a cycle of small gains eaten away by brokers commissions that will only prove profitable on the odd occasion. The other occasions will more than wipe that profit out and the frustration will drive you crazy if you start taking small gains and the stock takes off leaving you in the dust.
MJ is right...it may be other influences that create the selling... but I would only submit that the it is in addition to ongoing market manipulation.