U.S. biotech Genzyme, which has rejected an $18.5 billion offer from French drugmaker Sanofi-Aventis, appears to hold the upper hand in the takeover struggle, according to Geoffrey Porges, an analyst at Sanford Bernstein.

Porges, reiterating his "outperform" rating on Genzyme shares and raising his price target to $76, said he considers a sale of Genzyme as "almost inevitable" and sees a likely price of $77 to $78 a share. The Sanofi offer is $69 a share.

"This week's 'war of press releases' seems to have left the balance of power in Genzyme's hands, and we expect this to result in more value accruing to Genzyme shareholders than Sanofi's as this situation plays out," the analyst said in a research note to clients. Porges said he expects the negotiation process between Sanofi and Genzyme to open up in the coming months, likely resulting in an improved offer from Sanofi that will lead Genzyme to open its books to its suitor.

"That process should result in a higher bid from Sanofi, which we expect to be in the low to mid $70s," he said. Even that bid seems unlikely to meet the expectations of Genzyme's management and shareholders, but the company's ability to extract a bid above that level probably depends on either materially better conditions being found during due diligence or the emergence of another interested buyer. "We regard both as real possibilities, which could result in a price jumping into the $76 to $78 range."

He said the price could go "materially higher" than that if the sale of the company were to proceed along the lines of other competitively driven bidding processes seen in the industry. "We do not count on such an eventuality but regard it as a reasonable (25-35%) possibility in such a situation."

"We see increasing interest in the orphan drug market among global pharmaceutical companies, and with Genzyme being the preeminent player in that category, interest could come from a variety of global players seeking to 'jump start' their orphan drug businesses with a significant acquisition." Genzyme is the world's leading maker of drugs for rare, or orphan, diseases.