Forest Laboratories said on Thursday that Howard Solomon, who has led the biotech firm since 1977, will retire as chief executive officer at the end of this year and the company will name a successor by that time.

The company said it has been evaluating internal and external candidates.

Solomon, who is turning 86 in August, will continue in the chairman role until the annual shareholder meeting in 2014. He will stand for re-election to the board of directors at that time and become chairman emeritus.

Forest Labs adopted a shareholder rights plan last year after investor Carl Icahn built up a more than 10% stake in the company. In August of 2012 he won one of four board seats that he sought at the company after a bitter proxy fight.