The contest is also a test of universal proxy, a new S.E.C. rule that makes it easier for shareholders to vote for board candidates from different slates. Mr. Icahn has put up three nominees, challenging incumbent directors including Illumina’s C.E.O., Francis deSouza, and chairman, John Thompson. (He has argued that the two are too close.)
Mr. Icahn could very well win a seat. Influential shareholder advisory firms have offered the campaign some support. Institutional Shareholder Services backed an Icahn candidate, Andrew Teno, over Mr. Thompson, arguing that a more independent chair would have offered a better counterbalance “as the company navigated certain controversial decisions by management.” And Glass Lewis backed two Icahn nominees over Mr. Thompson and Mr. deSouza.
That may be enough to ensure that at least one of Icahn’s candidates, probably Mr. Teno, wins on Thursday. (Illumina had offered Mr. Icahn a board seat as part of initial settlement efforts, which the activist investor rejected.)
But Mr. Icahn himself still faces pressure elsewhere. The billionaire is battling the short seller Hindenburg Research, which has argued that Mr. Icahn’s publicly traded investment vehicle is overvalued and funds its dividends by selling new shares. (A former Icahn foe, Bill Ackman, again weighed in on the fight on Wednesday, suggesting shares in Mr. Icahn’s firm could fall yet more.)