New York (CNN Business) Gap chief executive Art Peck is stepping down ahead of the company's spinoff of its powerhouse Old Navy line, the company announced Thursday.

Peck, who has been at the company for nearly 15 years and has served as CEO since 2015, will be replaced after a brief transition by interim chief executive Robert Fisher, a son of the Gap's founders and currently the company's non-executive board chairman. Fisher has been with Gap for 35 years.

Peck, among the highest-paid chief executives in retail , has presided over several years of sales declines at the Gap brand. Gap's stock lost more than half its value during Peck's tenure and is trading at around $18 a share. Peck's compensation for 2018 was $20.7 million, filings show.

As the flagship name struggled and closed stores, Old Navy, Gap budget line created in 1994, continued to grow, topping $7 billion in sales last year.

Gap CEO Art Peck is stepping down ahead of the company's split with Old Navy.

Last year, Gap announced plans to spinoff Old Navy into a separate public company. Gap, which also owns Banana Republic, Athleta, Intermix, Hill City and Janie and Jack, and will hold onto those brands. It expects to complete the split in 2020.

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