Wayfair Inc. (NYSE: W) reported its third quarter financial results before the opening bell on Thursday. The Company topped revenue estimates, but reported a larger-than-expected loss for the quarter, sending shares plummeting by 17% at the opening bell.

For the third quarter, Wayfair reported revenue of USD 1.7 Billion, increasing 43.3% year over year and topping analysts’ estimates of USD 1.67 Billion. The Company reported an adjusted loss  per share of USD 1.28, while analysts’ polled for a loss of USD 1.09 per share.

Wayfair saw its active customers in its Direct Retail business reach 13.9 million, increasing 35.2% year over year. LTM net revenue per active customer was USD 443, increasing 8.6% year over year.

Orders per customer averaged out to 1.84 for the quarter, slightly increasing from 1.75 the same quarter last year. The continued growth was led by its repeated customers, who placed 66.3% of the total orders in the quarter. Total orders were 6.9 million in the quarter, increasing 59.7% year over year, as repeated customers placed 4.6 million of the total orders.

The higher costs were due to Wayfair expanding its advertising to attract new customers onto its sites, as orders primarily consisted of returning users.

According to CNBC, Neil Saunders, Managing Director of GlobalData Retail, said that over the year, online home furnishing store have added 3.6 million new active users, jumping 35% year over year.

He continued in the note and said that Wayfair spent USD 707 Million on advertising, which came out to USD 196 per customer, when customers only spent USD 443 on average. Saunders says the expenses towards attracting new customers was “rather excessive, and completely unprofitable, acquisition cost.”

Wayfair shares are up 22.82% this year.