I assume you mean a tax rate of 15% (not a change of 15% but a change to 15%)?
Readers here - due to your work - finding the right documents and doing the analysis -- can now see how important for F and F - for us long F and F - to not believe a 15% rate is coming
That is why I suggest for consideration the current move up in PPS may be "players" now disregarding such a low rate of taxation and plugging in 25% in their risk reward modeling
If and when 15% is likely - preferreds will stay level and common will drop 20-25% from says the PPS today