Shares in Swiss biotech Actelion (ALIOF) rose sharply in Zurich Friday on a report that it's attracted a bid from Johnson & JohnsonJNJ.

Actelion released its short statement after Bloomberg said the New Brunswick, N.J. company had approached the Swiss business with an offer worth about $17 billion. Johnson & Johnson confirmed the discussions midday Friday. 

People familiar with the situation told Bloomberg Actelion is working with an adviser to explore its options. Actelion couldn't immediately be reached for comment.

Actelion is led by fiercely independent co-founder Jean-Paul Clozel, who has for years resisted suggestions the company is a target. Other mooted suitors for Actelion over the years have included Shire (SHPG) - Get Report , which was last year reported to have made a takeover proposal for the business.

Actelion shares by late morning in Zurich were up 10.7% at Sfr174.90. At that price the company's stock is worth Sfr18.8 billion ($18.5 billion). The stock before Friday had risen more than 23% in the past year.

But Actelion shares fell 6%  on Oct. 20 when it reported disappointing nine-month figures amid worries about the U.S. outlook. Nine-month revenue was Sfr1.79 billion, up 14% on the year, and net profit was Sfr691 million, up 17%. Both figures strip out exchange-rate fluctuations.

Jeffferies analysts at the time argued that the share reaction was overdone, and said the company is a "compelling growth story," notwithstanding an expected mid-single digit decline in estimated 2017 profit.

Johnson & Johnson closed in New York Wednesday up 33 cents at $113.07. Johnson & Johnson has a market value of $307.6 billion and the stock's 12-month return is 14%.

Shire was up more than 2% on Friday morning in London.