CVS Health CEO Karen Lynch has stepped down with company shares down 19% and the national drugstore chain struggling. Lynch will be replaced by David Joyner, who will attempt to steer the health care giant through a worsening environment of rising medical costs. Joyner most recently served as executive vice president of CVS Health, and president of CVS Caremark. The company said it now anticipates third-quarter adjusted earnings of $1.05 to $1.10 per share, citing higher-than-expected medical cost trends. Analysts polled by FactSet predict earnings of $1.69 per share. CVS Health also announced on Friday that Chairman Roger Farah will now be executive chairman. Shares tumbled more than 12% before the market open. Close Thanks for signing up! Watch for us in your inbox. Subscribe Now Breaking News SIGN UP NOW