My guess Dabs is the increase in his postion to 8% has something to do with the warrants or swaps that he owns. I doubt if he is quietly buying common shares on the open market. It you think Ack is going to increase his 8% stake in GGP to something more meaningful by purchasing shares on the open market, I certainly do not see that.
As I have said several times, Ack is taking a very public beating on his JCP position right now, and I would suspect that all of his time and energy is going into how to salvage Pershing's hugh position in a company who is clearly losing market share every day to strong competitors like Macy's and Dillard's, and who many, very smart investors, think could see their core business permanently reduced.
Ack's investment in JCP could turn out to be the biggest blemmish of all time on his record. It was his big pick for 2012 and it is down almost 1/3 from where he bought it at $25 per share. As important as GGP was (and is) to him, I think it has taken a back seat to his problems at JCP.
Sandeep probably made those comments thinking Ack was too busy and distracted with other things to even notice what he said.
But what appears to be the case, is BAM and Flatt are operating as business as usual, and have seemed to dismiss the fuss that Ack tried to stir up a month or two ago.