sorry, but 10% issue capital will do diddly squat.
If you're going to spend that money on buyback, spend it all.
See my above post, but deadset, don't bother initiating a buyback if you are just doing it to put a floor or bow down to market forces bullying the board.
It will have to be a decisive statement, something along the lines of "if you want to short us, we'll take you on."