A big pharmacy benefit manager has failed in efforts to keep a competitor from marrying a giant retail drug store chain.

Shareholders of Caremark Inc., Nashville, Tenn., today voted to accept a $26.5 billion acquisition offer for Caremark from CVS Corp., Woonsocket, R.I.

A unit of Express Scripts Inc., St. Louis, had been trying to nominate 4 directors to the Caremark board and block the deal by making its own $27 billion offer for Caremark.

Caremark already has permission from federal antitrust regulators to proceed with the CVS deal, and it says it will proceed with the deal as soon independent inspectors certify the shareholder vote.

CVS says it will change its name to CVS/Caremark Corp. once it completes the acquisition.

Members of the Caremark board voted unanimously earlier this year to reject the Express Scripts offer, but the Express Scripts campaign reportedly persuaded some large Caremark shareholders to vote against the CVS deal.

Opponents of the Express Scripts offer noted that Express Scripts had not obtained approval for its proposal from federal antitrust regulators.