Groupon (Nasdaq: GRPN), the largest daily-deal website, reported third-quarter sales that missed estimates as demand faded for online coupons.

Net loss was $2.98 million, the Chicago-based company said today in a statement. Sales rose 32 percent to $568.6 million, missing a $591 million estimate.

Groupon, which has lost 80 percent of its value since holding an initial public offering a year ago, is struggling to offset the declining popularity of daily deals. As it relies on new sources of revenue including the e-commerce service introduced last year, Groupon Goods, margins are thinning, said Sameet Sinha, an analyst at B. Riley & Co. in San Francisco.

“The core business is slowing down dramatically and this other business is growing really fast,” Sinha said in an interview before the results. “It is very low-margin revenue so far.”

Groupon shares fell in extended trading following the report. Earlier, the stock advanced 4.3 percent to $3.92 at the close in New York.

Groupon also said Thursday it’s eliminating 80 sales jobs as it automates its sales and marketing operations. The company has more than 12,800 employees.

“Groupon announced several months ago it would be using technology to increase productivity through automation,” Julie Mossler, a spokeswoman for Groupon, said in an e-mailed statement before the earnings announcement. “We will always aim to optimize business operations wherever opportunities are identified.”

Online Discounts

The company makes money by offering discounts — known as Groupons — from businesses such as restaurants and nail salons. It then splits the revenue with the businesses.

Fourth-quarter revenue will be $625 million to $675 million, Groupon said in the statement. That compares with an average analyst estimate of $637 million.

Groupon last month unveiled an application for Apple Inc.’s iPad that lets merchants track purchases. The app works in conjunction with Groupon Payments, a credit card-reading service designed to compete with EBay Inc.’s PayPal and Square Inc.

LivingSocial Inc., the top rival to Groupon, had a net loss of about $566 million in the third quarter, partly because of an impairment charge on acquisitions, Chief Executive Officer Tim O’Shaughnessy told staff in a memo last month.