Barnes & Noble said the quarterly loss in its Nook division increased as the bookseller increased spending on its e-readers and tablets to keep pace with larger rivals Amazon and Apple .

Shares slid 11 percent to $14.26.

The top U.S. bookstore chain also said yesterday that sales growth in its core bookselling business slowed in the quarter.

Nook segment revenue rose 6 percent, but the company sold fewer Nook units at its owns stores.