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NEW YORK — Amgen said Sunday it will buy Onyx Pharmaceuticals for about $10.4 billion in cash in a deal that will add several cancer drugs to Amgen’s stable and to its pipeline of new drugs.

Amgen said it will pay $125 per share and expects to complete the deal in the fourth quarter. The companies value the deal at $9.7 billion excluding Onyx’s cash, and Amgen said it will use $8.1 billion in committed bank loans to finance the deal.

Onyx rejected an offer from Amgen worth $120 per share in June.

The new offer comes at a 44 percent premium to Onyx’s closing price June 28, before reports of Amgen’s initial bid.

Amgen is the world’s biggest biotech drug company, with a major presence in Seattle after acquiring Immunex in 2002. Its products include Prolia for osteoporosis, Enbrel for rheumatoid arthritis and skin disorders, and Neulasta and Neupogen for fighting infection in cancer patients.

The Thousand Oaks, Calif., company reported $17.27 billion in revenue in 2012. It said Onyx will start adding to its adjusted net income in 2015.

Onyx Pharmaceuticals makes two cancer drugs through a partnership with Bayer. Sales of Nexavar, a pill that is approved to treat liver and kidney cancer, totaled $861 million in 2012. Onyx received $288 million in revenue from those sales.

Stivarga was approved last September as a treatment for colorectal cancer and won additional approval in February for use against intestinal tumors.

In July, the FDA approved Onyx’s Kyprolis as a treatment for multiple myeloma, a blood cancer.

Onyx would add to Amgen’s pipeline of new drugs. In the first half of 2014 Amgen expects to announce late-stage testing data for three experimental drugs. The products are being studied as treatments for skin cancer, ovarian cancer and high LDL, or bad cholesterol, that doesn’t respond to pills such as Lipitor.

Onyx and Pfizer are also studying a drug called palbociclib as a treatment for breast cancer.