Doesn't CPG own some of the outstanding ARN shares?  I believe they own 20% ish.  Why would PBN acquire ARN shares with CPG as another large minority owner?  It makes the acquisition of ARN a little harder by any one party. 

OR maybe PBN bought the shares as a part of a bigger plan which has CPG buying PBN.  The combined ARN shares owned by CPG and PBN would be the largest % holder of ARN, making an ARN acquisition easier.  Then a large Chinese company buys CPG and gets it all!! haha, just fooling around in this second paragraph... sorry.