With common, you can dump your shares without tanking the PPS. Try dumping your preferreds, you will notice either no one is buying or the spread is HUGE. Dump at the bid on Preferreds and you will take a 30% hit, depending on where the pps is. You basically single handily tanked the preferreds.
Supply and demand.
As time goes by, there may be a demand for preferreds once the the assets are more clearer.