"If they knew windfall profits were coming, fair mkt value on 8/17/12 would not be just compensation. "
Fair Market Value isn't a lofty term. It has a definition. It is valued as the amount that a buyer is willing to pay and a seller is willing to accept on the open market.
In other words, it is the pps at the time of the taking.
This is why a takings claim is not shareholders best bet at recovery.