A Harley-Davidson director has resigned after expressing "grave concerns" about the current state of the company in a letter to the motorcycle maker's board. Shares of the company tumbled about 11% in morning trading on Thursday.

Four days before he quit the board, Dourdeville, who is with the New York investment firm H Partners, had called for the immediate resignation of Harley-Davidson Chairman and CEO Jochen Zeitz along with longtime directors Sara Levinson and Tom Linebarger.

Jared Dourdeville of the New York investment firm H Partners said the company had suffered from “cultural depletion.”