NEW YORK (AP) — Shares of Sears Holdings Corp. have tumbled after the ailing retailer announced that an executive of the company's second largest shareholder was resigning from is board.

The Hoffman Estates, Illinois, company said Monday that Bruce R. Berkowitz is stepping down from its board, effective Oct. 31. Berkowitz joined the board in February 2016.

Berkowitz serves as chief investment officer at Fairholme Capital Management, LLC, an investment advisory firm. FactSet lists Fairholme having a nearly 27 percent stake in Sears Holdings.

Sears has lost more than $10 billion over the past six fiscal years while struggling to keep pace with competitors like Walmart.

Sears' shares fell nearly 12 percent, or 78 cents, to $5.99.