The logo of Amazon is seen on the door of an Amazon Books retail store in New York City, U.S., February 14, 2019. REUTERS/Brendan McDermid

(Reuters) - Amazon.com Inc will close all of its U.S. pop-up stores and focus instead on opening more book stores, a company spokesperson said on Wednesday.

The company’s shares closed down 1.4 percent, while shares of bookseller Barnes & Noble Inc ended 8.9 percent lower.

Amazon’s 87 pop-up stores in the United States are expected to close by the end of April, the Wall Street Journal reported earlier on Wednesday, citing some of the employees at the stores.

The news underscores how the online retailer is still working out its brick-and-mortar strategy.

Pop-up stores for years helped Amazon showcase novel products like its voice-controlled Echo speakers, but the company is now able to market those products and more at its larger chain of Whole Foods stores, acquired in 2017, and cashierless Amazon Go stores, which opened to the public last year.

The online retail giant will also open more “4-star stores” - stores that sell items rated 4-stars or higher by Amazon customers, the spokesperson added.

“After much review, we came to the decision to discontinue our pop-up kiosk program, and are instead expanding Amazon Books and Amazon 4-star, where we provide a more comprehensive customer experience and broader selection.”