French pharmaceutical giant Sanofi-Aventis made public yesterday its $18.5-billion all-cash offer for the world's third-largest biotech firm Genzyme Corporation, after weekof waiting for a positive response from Genzyme on possible acquisition talks.

Under the terms, Genzyme shareholders are being offered $69 per share in cash, representing a 38-per cent premium over Genzyme's share price of $49.86 on 1 July 2010, a statement said.

The pharma major said that the offer price represents a multiple of 36 times Genzyme's 2010 earnings per share and 20 times its 2011 earnings, according to consensus estimates by analysts.

Sanofi CEO Christopher Viehbacher said, ''A combination with Genzyme represents a compelling opportunity for both companies and our respective shareholders and is consistent with our sustainable growth strategy.''

Last month, Sanofi-Aventis made an informal acquisition approach to Genzyme. (See: Sanofi-Aventis targets troubled Genzyme Corp for takeover).

Subsequently, the company submitted a non-binding offer on 29 July 2010 which was rejected by Genzyme.

In a letter addressed to Genzyme's chairman, president and CEO Henri Termeer, Viehbacher said: ''We are disappointed that you rejected our proposal on 11 August without discussing its substance with us.''

''Our financial advisors finally met briefly on 24 August, but the meeting simply served as further confirmation that as throughout you remain unwilling to have constructive discussions,'' he continued.

Sanofi-Aventis said that it has now made the offer public in order to inform Genzyme's shareholders of the significant shareholder value and compelling strategic fit in a combination of the two companies.

Massachusetts-based Genzyme is a leading bio-pharmaceutical company with products targeting rare diseases, kidney disease, orthopaedics, cancer, transplant and immune diseases, and diagnostic testing.

Sanofi-Aventis believes that its global reach and significant resources would allow Genzyme to accelerate investment in new treatments, enhance penetration in existing markets and expand further into emerging markets.

The combination of both companies is expected to create a global leader in developing and providing novel treatments, giving both companies significant new growth opportunities.

Sanofi-Aventis said that it has secured financing for the offer.

Paris-based Sanofi-Aventis is the world's fourth-largest pharmaceutical company with a market capitalization of approximately $75 billion, annual revenue of approximately $38 billion and annual EBITDA of approximately $16 billion.

Viehbacher further stated that Sanofi-Aventis is committed to a transaction with Genzyme and therefore, prepared to consider all alternatives to move things forward expeditiously.

According to analysts' expectations, the final deal could be reached in the range of $73 to $83 per share for Genzyme.