U.S. Markets open in 8 hrs 22 mins

Ipsen to buy Clementia Pharmaceuticals in deal worth up to $1.3 bln

* Ipsen shares dip, says deal to be dilutive on its margins

* Initial payment of $25/shr cash

* Takeover worth up to $1.31 billion (Adds share price reaction and analyst comment)

By Sudip Kar-Gupta

PARIS, Feb 25 (Reuters) - French healthcare company Ipsen has agreed to buy U.S. peer Clementia Pharmaceuticals in a deal worth up to $1.31 billion, the companies said on Monday, helping to boost Ipsen's portfolio of products treating rare diseases.

Ipsen's shares dipped 0.6 percent after the company said the takeover would initially weigh on margins due to the costs of forthcoming trials for Clementia products, but it hoped they would recover later on.

Ipsen said it would buy all of Clementia's shares for $25 each in cash upfront and offer a contingent value right (CVR) purchase of $6.00 per share, giving a total transaction value of up to $1.31 billion.

The companies said the initial cash offer of $25 per share marked a premium of around 70 percent to Clementia's recent average share price, which has been around $14.90.

"We essentially see this acquisition in a positive light, as it will strengthen Ipsen's pipeline of products from 2021 onwards," wrote French brokerage MidCap Partners.

Clementia has a key product called palovarotene that treats bone disorders, and it hopes to get full regulatory approval for the medicine in 2020.

"The acquisition of Clementia Pharmaceuticals accelerates the ongoing transformation of Ipsen as we are successfully executing on our external innovation strategy to identify and acquire innovative medicines to serve patients with unmet medical needs," said Ipsen Chief Executive David Meek.

The Ipsen/Clementia deal marks the latest example of consolidation in the global healthcare industry, as companies pounce on smaller rivals with potentially lucrative products.

On Monday, Roche said it would buy Spark Therapeutics in a $4.3 billion deal, while last year Sanofi bought Bioverativ and Ablynx in two blockbuster deals. (Reporting by Sudip Kar-Gupta; Editing by Gopakumar Warrier and Mark Potter)