Amazon’s furniture sales are on the move: A One Click Retail study found that the eCommerce retailer has more than tripled sales in that category since 2015. And, in 2017, furniture brought in approximately $4 billion, retail news source Chain Store Age reported.

“It’s clear that the furniture market is a valuable investment for Amazon, and it’s equally true that Amazon is a valuable investment for furniture brands,” according to One Click Retail’s “Furniture: The Amazon Effect” study.

Amazon’s largest furniture category is mattresses, with sales of around $1.1 billion, marking a jump of 82 percent in comparison to 2016. The retailer’s second-largest category is bedroom furniture, with $800 million in sales, marking year-over-year growth of 45 percent. The company’s most successful furniture items are its AmazonBasics office chairs.

The news comes as Amazon was gearing up in 2017 to build four or more warehouses to handle what it expects to be booming orders of bulky household items. According to a report in The Wall Street Journal, while Amazon has been selling furniture for some years, now the eCommerce giant is pursuing the category in a much bigger way. By growing in this segment, Amazon is taking on the likes of Wayfair and Pottery Barn in the online furniture market.

Furniture was the second fastest-growing segment of online retail in the U.S., with only groceries ahead of it. Citing Barclays, the Wall Street Journal reported that sales in the online furniture segment grew 18 percent in 2015. Meanwhile, IBISWorld said around 15 percent of the $70 billion of the furniture market in the U.S. comes through sales on the internet.

“Furniture is one of the fastest-growing retail categories here at Amazon,” Veenu Taneja, furniture general manager at Amazon, said in a statement to the WSJ. The executive said Amazon is expanding its offering, including adding more Ashley Furniture sofas and Jonathan Adler home décor.

(Source: Forbes)