(Reuters) – Activist investor Carl Icahn on Monday launched a proxy fight at Illumina Inc, arguing the company’s takeover of Grail Inc had cost shareholders about $50 billion since the closing of the deal.

Shares of Illumina jumped 18% to $228.97 in morning trade.

Icahn plans to nominate three people to Illumina’s board at the company’s upcoming shareholder meeting, he said in a letter sent to the life sciences company’s shareholders.

Icahn also said he had been working privately with Illumina’s board for the last few weeks but could not come to an agreement.

The proxy battle comes as Illumina is opposing a European Union order to divest cancer-detection test maker Grail, after the life sciences company jumped the gun and closed the deal in August 2021, without securing regulatory approval.

“We have therefore determined to launch a proxy contest to attempt to gain board representation,” Icahn said, adding he feared the company’s board will continue to pursue the Grail transaction.

Illumina did not immediately respond to a Reuters request for comment.

(Reporting by Bhanvi Satija in Bengaluru; Editing by Anil D’Silva)