Wound care firm Smith & Nephew rejected a $10.9 billion acquisition offer from Johnson & Johnson.

Smith & Nephew CEO David Illingworth declined to comment on the bid, sending his firm’s stock prices soaring by more than 10%. “Speculation has been going on for 10 years,” he said at a J.P. Morgan Healthcare Conference in San Francisco.

J&J spokesman Jeff Leebaw also declined comment.

Sky News reported that Johnson & Johnson approached its rival in December with the  11-figure proposal. But the outlet did not cite sources, or indicate where it had received its information.

Johnson & Johnson was considering whether or not to come back with a raised offer, according to several other published reports.

The allegation that Smith & Nephew received and rejected a bid without informing shareholders reopened debate on when companies should be required to make bids known to the market.

It is generally accepted that companies should not have to reveal all bids received. Some argue that there must be something wrong with the system if boards can withhold information about serious bids.