Billionaire investor Carl Icahn is giving up his bitter takeover fight for Dell Inc. a few days before shareholders are scheduled to consider the latest buyout offer from the struggling computer maker’s founder Michael Dell.

Icahn said Monday in a letter to shareholders that he still thinks Michael Dell’s bid to take his company private undervalues the business and freezes shareholders out of any future gains. But Icahn also said it would be “almost impossible” to defeat that offer in a vote scheduled for Thursday.

Icahn and another major Dell shareholder, Southeastern Asset Management, said they won’t pursue additional efforts to defeat it.

“We therefore congratulate Michael Dell and I intend to call him to wish him good luck (he may need it),” Icahn wrote in the letter.

Michael Dell’s $24.8 billion bid to take his company private includes an offer of $13.75 per share plus a 13-cent dividend. Dell raised that bid last month after previous offers also drew strong criticism from Icahn and other major Dell Inc. investors.

Dell’s shares have plunged by more than 40 percent since Michael Dell returned for a second stint as CEO in 2007, largely because the company has had trouble adapting to a technological shift that has caused PC sales to fall as more people use smartphones and tablets.

Icahn has said Michael Dell’s buyout would keep stockholders from sharing gains the company will reap from an eventual turnaround.