Health care giant Johnson & Johnson reportedly is close to buying biopharmaceutical company Pharmacyclics, its longtime partner in developing blood cancer treatment Imbruvica.

A corridor at the headquarters of Johnson & Johnson in New Brunswick . (AP Photo/Mel Evans, File)

London's Financial Times reports "people familiar with the matter" say Johnson & Johnson's anticipated offer would value Pharmacyclics of Sunnyvale, California, above its current $17 billion market capitalization. Those sources said a deal could be announced within days but might unravel.

J&J spokeswoman Amy Meyer declined to comment.

Pharmacyclics shares surged on the rumor, jumping 6.3 percent in regular trading and another 3 percent after hours to $237.48.

Johnson & Johnson, based in New Brunswick, New Jersey, usually makes mid-sized acquisitions worth several billion dollars, but paid $21.3 billion in 2011 for Synthes, a Swiss maker of orthopedic surgical equipment. J&J has annual revenue of $74 billion.

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