After 15 years with the company, Mattel’s chief executive and chairman Bryan Stockton (pictured) is resigning from his position, as Christopher Sinclair takes the reins as chairman and interim CEO.

Sinclair, a member of Mattel’s board of directors since 1996, steps into the new role immediately. Stockton became Mattel’s chief exec in 2012. He is also resigning immediately from his spot on the company’s board of directors.

The exec shuffle comes as the El Segundo, California-based toyco’s sales slump extends to five quarters, with holiday-season earnings falling below analyst estimates. Worldwide net sales in the fourth quarter were US$1.99 billion, down 6% from last year.

Mattel also continues to struggle with slowing sales for its Barbie and Fisher-Price brands, and recently lost the Disney doll license to Hasbro for properties including Frozen and Disney Princess.

According to Sinclair, Mattel is working to revitalize the business and to find a new leader for the company in the coming months.

The news comes on the heels of Mattel extending the roles of Richard Dickson and Tim Kilpin, who have added the title of president to their current roles.