SAN FRANCISCO (MarketWatch) -- CVS Caremark Corp. /quotes/comstock/13*!cvs/quotes/nls/cvs (CVS 31.37, -2.43, -7.18%) said Monday it was "surprised and disappointed" by Walgreen Co.'s /quotes/comstock/13*!wag/quotes/nls/wag (WAG 30.35, -0.49, -1.59%) announcement it will no longer participate in any new or renewed prescription-drug plans awarded to CVS's pharmacy benefit-manager business. CVS criticized Walgreen's move as disruptive to plan members. "Walgreens has tried this approach several times in the past, targeting employers, health insurers and government entities," CVS said in a statement. "Today's announcement by Walgreens is nothing more than a transparent effort to raise its reimbursement rates at the expense of plan sponsors and members and illustrates an inability to adapt to the demands of the marketplace in today's challenging and rapidly evolving health care environment." CVS shares dropped 7.3% and Walgreens shares fell 1.7% in recent activity.