UPDATE 1-Sanofi CVRs tied to Genzyme may start trading April 4
* CVR trading depends on outcome of improved tender offer
* Tender offer expires on April 1, 11:59 PM New York time
* CVRs to trade on Nasdaq exchange under ticker GCVRZ.O
PARIS, March 29 (Reuters) - Certificates related to Sanofi-Aventis's (SASY.PA) $20.1 billion acquisition of U.S. biotech firm Genzyme GENZ.O could begin trading on Nasdaq as soon as April 4, depending on the outcome of its tender offer.
The French drugmaker said on Tuesday that the U.S. Securities and Exchange Commission (SEC) had cleared the trading of contingent value rights (CVR) under the ticker GCVRZ.O.
Sanofi-Aventis clinched its long-sought deal to buy Genzyme in February with a sweetened offer that comprises cash and the possible payment under the CVRs of additional amounts geared to the future performance of several of the U.S. group's drugs. [ID:nLDE70U1H1]
Sanofi's improved tender offer of $74 a share plus one CVR per share will expire just before midnight New York time on April 1. The offer could be extended should Sanofi fail to get at least 50 percent of Genzyme's shares.
Genzyme shareholders could receive one-time milestones and payments if production levels of two of Genzyme's key rare disease drugs Cerezyme and Fabrazyme are met following a shortage due to contamination problems at a manufacturing plant.
Other milestone fees depend on whether Genzyme's multiple sclerosis drug Lemtrade wins U.S. marketing approval and if sales of the drug hit specified targets.
Sanofi shares closed little changed on Tuesday, up 0.1 percent at 49.10 euros. (Reporting by Caroline Jacobs; Editing by Greg Mahlich)