BERLIN, Germany — Online fashion retailer Zalando said it expected sales growth to slow to 15 to 20 percent in 2020 after it reported a strong final quarter to 2019, boosted by a strong performance in the "cyber" week around the Black Friday discount day.

Fourth-quarter sales rose 19.5 percent to €2 billion ($2.1 billion), while adjusted earnings before interest and taxation came in at €110.4 million, both ahead of average analyst forecasts.

While it expects sales growth to come in at 15 to 20 percent in 2020, it said it expected gross merchandise volume — sales made on its website by itself or its partners — to rise 20 to 25 percent as it becomes more of a platform for brands rather than buying and selling stock itself.

By Emma Thomasson; editor: Riham Alkousaa.