Keith Meister's Corvex Management disclosed buying Illumina stock during the last three months of 2023 and owning 730,084 shares on Dec. 31.

The buying came after the stock price edged lower for most of the year even after investors sided with Icahn's arguments that changes were needed at the company and elected one of his director candidates to Illumina's board.

Meister, who founded his firm in 2011 after serving as Icahn's lieutenant, did not immediately respond to a request for comment.

Filings also showed that ValueAct Capital, run by Mason Morfit, owned 328,045 shares at the end of December. ValueAct had established its Illumina position in the third quarter of 2023 and cut its stake by 37% in the fourth quarter. The firm did not immediately respond to a request for comment.

Since Icahn's board challenge early in 2023, the company announced the departure of Francis deSouza who had been CEO and its decision in December to divest cancer blood test maker Grail after regulatory objections.

A day after Illumina said it will part with Grail, Icahn sent a letter to other Illumina shareholders saying that he plans to oust directors, laying the groundwork for a second board challenge. He has not offered details on his plans since then and did not respond to requests for comment on Wednesday.

At the end of December, Icahn owned 430,000 Illumina shares, the same as in the previous quarter, his filing shows.

(Reporting by Svea Herbst-Bayliss; Editing by Stephen Coates)

By Svea Herbst-Bayliss