Shares in Swiss vaccine maker Berna Biotech rose sharply on Monday after Swiss pharmaceuticals company Novartis said it was considering a cash bid.
It had appeared that the sale of Berna Biotech to Novartis's smaller Dutch rival Crucell was already a done deal.
Berna Biotech's stock was up 12.5 per cent at SFr15.30 ($11.80) at close of trade on Monday after Novartis said it was looking at Berna's books with a view to bidding for the firm and combining it with its newly acquired Chiron vaccines business.
Analysts said Novartis's interest in Berna highlighted the potential benefits of a transaction.
They added that Berna, with a market value of around SFr550 million, would be a relatively small deal for the acquisitive company.
Shares in Crucell were also up – rising just under five per cent to €21.30 (SFr33) on Monday.
Crucell, for its part, emphasised that it remained committed to Berna.
"Crucell's offer is the only offer that has been made," it said in a statement. "It is recommended by the board of Berna, and confirms that Crucell remains committed to the proposed transaction."
Novartis said the economic terms of an offer for Berna had not yet been determined and that no assurance could be given that Novartis would in fact make a bid.
But the Basel-based pharmaceuticals giant confirmed that any offer would be made in cash.
Experts say it is an apparent attempt to make the deal more attractive to investors since it removes the risks attached to Crucell's share price.
Crucell's bid valued Berna at around SFr591 million when it was announced on December 1.
The proposed tie-up was designed to fuel growth at the Dutch firm, which has yet to turn a profit.
Novartis CEO Daniel Vasella has long been a champion of mergers and has spent around $14 billion (SFr18 billion) so far this year on various acquisitions to bolster Novartis's businesses.
In addition to buying generic drug makers, Novartis has made an offer for the remaining shares in the United States firm Chiron which it did not already own. It could thus create a fourth business unit based around the fast-growing vaccines industry.
Analysts noted that Berna has a portfolio of hepatitis A and B vaccines, flu vaccines and various experimental drugs.
swissinfo with agencies
Berna Biotech, formerly the Swiss Serum and Vaccine Institute, was founded in 1898.
It is based in Bern and has around 700 employees in Europe and South Korea.
It specialises in vaccines against hepatitis B and respiratory and tropical diseases.
Crucell and Berna combined would become the largest independent vaccine company in the world.
Biotechnology is a technology based on biology, especially when used in agriculture, food science and medicine.
"Red biotechnology" is biotechnology applied to medical processes.
"White biotechnology", also known as grey biotechnology, is biotechnology applied to industrial processes.
"Green biotechnology" is biotechnology applied to agricultural processes. Whether green biotechnology products are ultimately more environmentally friendly is a topic of considerable debate.
"Blue biotechnology" has been used to describe the marine and aquatic applications of biotechnology.