In a regulatory filing, Biogen Idec acknowledged that its $17-a-share tender offer expired at midnight yesterday, and said it would return to stockowners the minority of shares that were already turned over to the company.
Biogen Idec faced an uphill battle after Facet, based in Redwood City, Calif., disclosed last week it was talking to other unnamed parties about selling at a higher price.
Facet's board had recommended that stockholders reject Biogen Idec's bid, valued at $420 million, but offered to negotiate directly with Biogen Idec and other potential acquirers.
Amy Reilly, a Biogen Idec spokeswoman, would not say whether Biogen Idec plans to enter into face to face negotiations with Facet, with which the Cambridge biotechnology company is collaborating on the development of drugs to treat cancer and multiple sclerosis.
"Our offer expired at midnight," Reilly said. "A majority of the outstanding Facet shares were not tendered, and beyond that we have no comment."
To read a recent Globe story about Biogen Idec and Facet, please click here.