June 28 Biotech Amgen Inc has offered to buy smaller biotech Onyx Pharmaceuticals for $120 per share in cash, Canadian newspaper Financial Post reported on Friday, sending Onyx shares up about 30 percent in after-hours trading.
The Financial Post said that documents it had seen said that Amgen had sent material to Onyx in which it said it would propose a cash acquisition worth about $10 billion and requested due diligence and a document review period.
The Financial Post said that Amgen had sent the documents to Onyx about two weeks ago. Both companies are based in California.
In a research note, ISI Group analyst Mark Schoenebaum said that were a deal to occur, Onyx's Kyprolis cancer drug would fit well into Amgen's cancer drug sales and marketing infrastructure and complement Amgen's portfolio of cancer drugs.
Onyx shares were trading at $111 after closing at $85.20, an increase of $25.80, or about 30 percent. Amgen shares were trading at about $98 after-hours after closing at $98.61.
Spokeswomen at Amgen and Onyx declined to comment.