French drug giant Sanofi-Aventis SA announced that it has submitted a non-binding proposal to acquire American biotech firm Genzyme Corp. — in an all-cash transaction valued at approximately $18.5 billion.

Under the terms of the proposed acquisition, Genzyme shareholders would receive $69 per Genzyme share in cash, representing a 38 percent premium over Genzyme's unaffected share price of $49.86 on July 1.

The move Sunday came nearly two months after rumors first surfaced on July 2 that Sanofi was looking to buy an American drugmaker in a bid to help replace revenue being lost to worsening generic competition. Since then, Sanofi unexpectedly got generic competition on July 23 for its blockbuster injected anticlotting drug, Lovenox, which brought Sanofi $3.9 billion last year.