Sears Holdings Corp. tumbled the most in 8 1/2 years after saying it will close as many as 120 stores, with a deeper-than-expected sales decline casting doubt on Chairman Edward Lampert’s efforts to turn around the chain.

Lampert has tried several strategies since merging Sears with Kmart in 2005, none of which have reversed falling sales.His latest push involves moving toward smaller stores and licensing the Craftsman, DieHard and Kenmore brands. As a result, the larger stores have received less investment and prompted customers to shop elsewhere, according to Gary Balter, an analyst with Credit Suisse Group AG in New York.