
Shares of drug developer Keros Therapeutics KROS.O rise 17.4% to $12.09 premarket
KROS says its board had authorized a stockholder rights plan, also known as a "poison pill", in response to the rapid accumulation of co's stock by some investors
Co also launches a process to evaluate strategic alternatives, including a possible sale
Up to last close, shares have fallen 34.7% YTD