Swiss biotechnology firm Serono slumped to its lowest level in more than three years yesterday after a report in the Wall Street Journal said its efforts to find a buyer had hit the buffers.

Serono said in November it had appointed Goldman Sachs to try to find a buyer or merger partner setting a deadline of last Friday to secure an offer. But none of the companies rumoured to be looking at the firm – including Novartis, GlaxoSmithKline, Sanofi-Aventis and Pfizer – have stepped forward, according to the report.

One of the front-runners among the takeover candidates, Novartis, appeared to rule out an acquisition of such a size at its annual results conference last week, saying big acquisitions were unlikely, although smaller deals may be considered.

Analysts have estimated that Serono could ask as much as $15 billion for the entire company, which markets the phenomenally successful multiple sclerosis drug Rebif (interferon beta-1b). But Rebif has seen its momentum slow, particularly in the US market, and observers have pointed to a weakened pipeline at Serono in the wake of several product failures.

Serono’s shares fell more than 9% to 975 Swiss francs yesterday in the wake of the WSJ article. The company said it was continuing to evaluate its strategic options with its advisors.