CAMBRIDGE, Mass. ( TheStreet) -- French drug maker Sanofi-Aventis ( SNY) has reportedly approached Genzyme ( GENZ) about a potential acquisition of the biotech firm, according to media reports.

Genzyme shares soared more than 21% to $66 after the Wall Street Journal and others reported that Sanofi has approached Genzyme about a possible deal. The talks between the two companies are in the early stages and an acquisition may not happen, the Journal reported.

Earlier this month, Sanofi was reported to be interested in making an acquisition and was willing to spend as much as $20 billion. At that time, Genzyme was mentioned as a possible target, as was Biogen Idec ( BIIB) and Allergan ( AGN).

Shares of both Biogen and Allergan fell as news of the Sanofi-Genzyme talks broke.

Meantime, Sanofi also learned Friday that FDA approved a generic version of its top-selling blood thinner Lovenox made by Novartis ( NVS) and Momenta Pharmaceuticals ( MNTA). With sales of almost $4 billion last year, Lovenox is Sanofi's second-largest drug, so the entry of a generic competitor is a blow.

-- Reported by Adam Feuerstein in Boston.

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