Mitchell Klipper, CEO of book retailer Barnes & Noble, says that E.L. James’ Fifty Shades of Grey trilogy has “had the biggest impact in the numbers.”

The news came via an earnings call today when the company spoke about narrowing its quarterly loss compared to last quarter. Sales have climbed 2% since their last.

Fifty Shades has been on a role lately in terms of sales. The three books have been consistently on the top of Amazon’s bestseller list over the past few months (except for when it was temporarily unseated by a Zelda book yesterday). On Amazon UK, the series unseated Harry Potter atop the all-time bestseller list.

A film based on the book is currently in development. Michael De Luca and Dana Brunetti will be producing.