Since Ackman doesn't report his GSE holdings any longer, it's possible (likely?) that he has fully Rotated into Preferreds and joined forces with Perry, Berkowitz, Paulson, et al.
I'm sure he saw this style recap coming 100 miles away. He publicly shouted to "Buy Commons" while he was unloading his holdings only to be buying Preferreds all along -- possibly even taking a Short position in Commons.
We can't rule out this possibility. Ackman is sneaky like that.