I'm not saying it's a pump-and-dump. What I am saying is that Icahn (and others like him) are very careful to hide their purchases from the market while they a

I'm not saying it's a pump-and-dump. What I am saying is that Icahn (and others like him) are very careful to hide their purchases from the market while they are still purchasing, in order to prevent their own purchases from unduly raising the price. If anything, Icahn's tweet signals that he is no longer purchasing AAPL in quantity. Now he wants the market to "catch up" to his value appraisal so he can realize a gain.