Carl Icahn
Billionaire activist-investor Carl Icahn gives an interview on FOX Business Network. REUTERS/Brendan McDermid

Activist investor Carl Icahn and San Diego-based Illumina failed to reach a settlement during weeks-long private negotiations before he began a proxy fight earlier this month, a regulatory filing showed on Thursday.

Icahn, a legendary “corporate raider” who now owns 1.4% of Illumina, has been pushing for the genetic sequencing pioneer to unwind its buyout of cancer detection test maker Grail and is seeking three board seats.

In a preliminary proxy filing, Illumina disclosed that the billionaire had proposed a negotiated settlement on March 8.

The proposed terms included two seats on the board for Icahn nominees and a mutually-agreed candidate. He also suggested a joint statement supporting the divestiture of Grail, if the company’s appeal to European regulators was not successful.

A day later, Illumina counter proposed one seat for an Icahn nominee and another for an independent candidate on its board. However, Icahn declined the offer and also withdrew his negotiated proposal.

Illumina said Icahn “was not willing to consider anything less than appointment of all three” nominees, according to the filing on Thursday.

On March 13, Icahn released a letter to Illumina shareholders, launching the latest in this year’s series of high-profile proxy fights, after Nelson Peltz ended his quest for a seat at Disney, Daniel Loeb reached an agreement with Bath & Body Works and Elliott Management withdrew its nominees at Salesforce.

In a recent interview with the Wall Street Journal, Icahn also indicated that Illumina should bring former CEO Jay Flatley back.