Biogen Idec Inc. (BIIB) is going public with a $356 million unsolicited offer for drug developer Facet Biotech Corp. (FACT), after claiming that the smaller company shunned earlier attempts to reach a deal.

The $14.50-a-share offer for the Redwood City, Calif., company brings a 64% premium to Thursday's closing price. Shares were halted for news Friday, last trading at $8.79. Biogen shares rose 2.1% to $50.97.

Facet officials weren't immediately available to comment on the offer.

Notably, the offer is close to the amount of cash that Facet holds on its balance sheet, which may make the company hesitate to agree such a deal.

"That is not going to get a deal done," said BMO Capital Markets analyst Jason Zhang, who has a $14 price target on the company, based mostly on its cash holdings.

Biogen officials weren't immediately available for comment.

Facet Biotechnology was spun off from PDL BioPharma Inc. (PDLI) in December in order to separate the company's biotech assets from its royalty producing assets. PDL is essentially a shell company that produces revenue from its patent portfolio and license agreements.

After the spinoff, Facet had $405 million in cash in order to fund its operations for a number of years while it attempts to develop its pipeline. It has projected spending $110 million in 2009, and had $371.1 million, as of June 30, 2009.

That amounts to $15.12 a share in cash, based on its 24.5 million shares outstanding, although the company recently signed a collaboration with Trubion Pharmaceuticals Inc. (TRBN) to pay $20 million upfront and make a $10 million investment in the company.

Zhang declined to estimate how much Biogen might have to pay to close the deal, but conceded that Biogen is the most likely bidder for Facet.

The two companies have worked together since 2005 on treatments for multiple sclerosis and solid tumors.

According to Biogen, it first expressed interest in Facet in mid-August, offering $15 a share and urging it to not undertake any material transactions.

Biogen contends that Facet rejected its offer and subsequently signed the deal with Trubion.

Biogen said it believes that the Trubion agreement "reduces the value of Facet, as apparently do Facet's investors", citing a 22% drop in its stock price since the deal. It also pointed to the deal in explaining its lowered $14.50-a-share offer.

-Thomas Gryta, Dow Jones Newswires; 212-416-2169; thomas.gryta@dowjones.com

(Jay Miller contributed to this story)