Barnes & Noble (BKS) - Get Report on Thursday announced that COO Demos Parneros will become the company's CEO effective immediately, the latest in a long series of executive turnover at the embattled bookseller.

Parneros takes over from Leonard Riggio, longtime chairman of the company and its largest shareholder. The new CEO was named Barnes & Noble's COO on Nov. 21, joining from Staples (SPLS) , where he was president of its North American Stores & Online division. Parneros began at Staples as the general manager of its first New York City store in 1987 and rose through the management ranks. Since 2014, Parneros has served as a director at KeyCorp (KEY) - Get Report and privately held Modell's Sporting Goods.

Here's a look at Barnes & Noble's high degree of CEO turnover over the past few years.

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Editors' pick: Originally published April 27.