Merck to Buy Rosetta for About $620 Million

Merck & Co. said it will acquire biotech company Rosetta Inpharmatics Inc. for about $620 million in hopes its genomic research tools will help speed development of new medicines.

The drug giant said it will pay 0.2352 share for each share of Rosetta, representing an 82% premium on Rosetta based on Thursday’s closing prices. Rosetta shares rocketed nearly 75%, or $7.43, to close at $17.34 on Nasdaq, while shares of Whitehouse Station, N.J.-based Merck closed off 58 cents at $75.94 on the New York Stock Exchange.

Merck Chairman Raymond Gilmartin said the transaction was consistent with the company’s emphasis of expanding its “lead in cutting-edge science,” and that future acquisitions probably would be on a similar scale. The deal gives Kirkland, Wash.-based Rosetta an opportunity to move beyond providing research tools and software and into drug discovery.