Quote from Rearden Metal:
Rumors that Ackman has somehow fallen in love with ADT will not only turn out to be completely false, I doubt they were ever half sincere to begin with. BSD managers have been gradually building their short positions in ADT for months now, because they see what I see; Aggressive new competitors grabbing market share, undercutting pricing, and all but ensuring an ADT earnings miss at some point in the near future.
So how do they temporarily boost the share price and get more shares short at overvalued prices? Spread bullshit rumors, that's how... and it worked like a charm. The marks & suckers and got long ADT today, while the smart money sat there boosting their short positions and laughing at them. You'll see, just wait...
You were correct that Bill Ackman did not plan to buy a huge stake in ADT, and this is probably a big reason for the decline in ADT stock today.
http://www.businessweek.com/articles/2013-07-31/bill-ackmans-2-billion-bet?google_editors_picks=true