Actelion’s (ALIOF) shares traded 10% lower amid concern among investors that J&J’s exit made a successful deal for Europe’s biggest biotech group less likely.

Sanofi (SNYNF) declined to comment.

The French drugmaker was trumped in August by Pfizer’s $14 billion bid for U.S. cancer drug company Medivation and is still eager for deals to broaden its drug line-up.

However, analysts said Sanofi CEO Olivier Brandicourt could ill afford to fail in a second high-profile bid.

Actelion told J&J (JNJ) it was confident it could attract an offer significantly higher than the approximately 250 Swiss francs per share the U.S. company had offered, according to one person familiar with the matter.

There were also disagreements about the proposed deal’s structure, the person added.

Actelion shares had closed at 208.50 Swiss francs on Tuesday, a 25% premium to their price before J&J’s bid became public two weeks and giving the company a market capitalization of 22.5 billion Swiss francs ($22.2 billion).

“I presume these parties are prepared to make offers that are more attractive than that which J&J was envisaging,” said Eleanor Taylor Jolidon, a fund manager at Union Bancaire Privee in Geneva, which is among Actelion’s top 40 investors.

“Otherwise, the board of directors would not have acted in the interests of the stakeholders by creating a situation in which J&J walked away.”

CEO’s Pivotal Role

The Swiss company, founded by its chief executive Jean-Paul Clozel in 1997, confirmed talks over a “possible strategic transaction” but did not name the counterparty.

A spokesman declined further comment but sources with knowledge of the matter identified Sanofi.

Analysts have previously named Sanofi as a potential buyer for Actelion, whose portfolio of drugs against deadly pulmonary arterial hypertension—elevated pressure in arteries connecting the heart and lungs—would supplement Sanofi’s Genzyme rare disease unit.

Even so, a competitive auction could drive up its price to unrealistic levels.

“Winning a bidding war when it comes to acquiring biopharmaceutical companies almost always equates to way over-paying,” wrote Tim Anderson, an Bernstein analyst.

“These are not bragging rights,” he said. “If Actelion were to go out at around $30 billion, this equates to around 13 times sales and 30 times earnings before interest and taxes. These are high figures.”

A source close to J&J said the main problem was Clozel did not want to sell. “It wasn’t about price, he simply doesn’t want to give up control,” the source said.

Clozel and his wife, Chief Scientific Officer Martine Clozel, have built up a world-leading drug portfolio at Actelion to treat pulmonary arterial hypertension.

They aim to expand in drugs for multiple sclerosis and clostridium difficile, but regulatory approvals for those are years away.

The company is also counting on its new pulmonary arterial hypertension treatments Opsumit and Uptravi, which combined are forecast to bring in nearly 4.5 billion francs in annual sales by 2020.

Clozel has rebuffed past pressure from some shareholders to do a deal, maintaining Actelion is better off staying independent. Five years ago, he successfully fended off an effort by activist hedge fund Elliott Management to put Actelion up for sale.