Call it the curse of Harry Potter.

Shares in bookseller Barnes & Noble (BKS) tumbled nearly 12 percent Thursday after the company reported a sharp drop in quarterly sales.

It said part of the blame was that in the same period last year, its sales got a big boost by the release of "Harry Potter and The Cursed Child." There was no similar hot seller in this year's quarter.

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The New York-based company's total sales fell nearly 8 percent in its fiscal second quarter that ended Oct. 28 compared to last year, fueling a loss of $30.1 million. The company had a loss of $20.4 million in the same quarter last year.

Its sales at established stores fell 6.3 percent, with the company attributing half of that decline to the sales period being compared to last year's quarter that featured the release of the script book for the Harry Potter play of the same name. The company blamed the remainder of the decline on its non-book products and said it would focus more on selling books while trimming its toy and game selections.

It said it expects sales at established stores to be about flat for the rest of its fiscal year.

Two weeks ago, Barnes & Noble's shares surged after activist investor Sandell Asset Management proposed buying the bookseller and taking it private. Barnes & Noble said it did not take the offer seriously.

The company said it had a loss of 41 cents per share for the quarter. Three analysts surveyed expected an average loss of 26 cents for the quarter. In the second quarter last year, Barnes & Noble lost 29 cents per share.

Barnes & Noble posted revenue of $791.1 million in the period, less than the $811 million two analysts surveyed had expected.

Shares in Barnes & Noble Inc. fell 90 cents to close Thursday at $6.90. The company's shares have dropped more than 45 percent in the past 12 months.