NEW YORK -- Biotech drugmaker Amgen ( AMGN) will buy cancer drug maker Onyx Pharmaceuticals ( ONXX) for about $10.4 billion in cash in a deal that will add several cancer drugs to Amgen's stable and add to its pipeline of new drugs. Amgen Inc. said Sunday it will acquire Onyx for $125 per share, and it expects to complete the deal at the beginning of 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. Amgen is the biggest biotech drug company in the world. Its products include Prolia for osteoporosis, Enbrel for rheumatoid arthritis and skin disorders, and Neulasta and Neupogen for fighting infection in cancer patients. The company, based in Thousand Oaks, Calif., reported $17.27 billion in revenue in 2012. It said Onyx will start adding to its adjusted net income in 2015. Onyx Pharmaceuticals Inc. makes two cancer drugs through a partnership with Bayer AG. 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 in September as a treatment for colorectal cancer, and won additional approval in February for use against tumors of the intestinal tract that did not respond to other treatments. In July the Food and Drug Administration approved Onyx's Kyprolis as a treatment for multiple myeloma, a type of blood cancer. Multiple myeloma causes tumors to grow in the bone marrow, preventing the production of normal blood cells. The FDA approved Kyprolis for patients who have already been treated with at least two other multiple myeloma drugs, and Onyx is conducting other trials to win broader marketing approval. Onyx and Bayer are also testing Nexavar as a treatment for breast cancer. The new offer comes at a 44 percent premium to Onyx's closing price on June 28, before reports of Amgen's initial bid. In the days after Amgen's first offer was made public, shares of the South San Francisco company climbed as high as $136.87. The stock closed at $116.96 Friday.