This is the first time I have ever heard of this. Doesn't mean it's never been done before, but I've never heard of it, so I don't know what it means.
I've got some research to do re: preferred and common shares and how preferred shares count in figuring price/earnings ratio. That seems to me like one side of the coin.
The other must be whatever advantage there is to the shareholder to have preferred rather than common shares.