MILAN, Italy — Yoox Group, operator of e-commerce stores for brands from Armani to Zegna, repeated its guidance of revenue and earnings growth in 2013 after quarterly sales rose 18 percent, buoyed by demand in Italy and North America.

Second-quarter revenue grew to 97 million euros ($128.8 million) from 81.9 million euros a year earlier, Bologna, Italy- based Yoox said today in a statement after European markets closed. Sales grew 19 percent in Italy and 31 percent in North America, its biggest market. Net income, excluding incentive plan costs, climbed 19 percent to 1.8 million euros.

Yoox, which last year set up an e-commerce venture with Gucci-owner Kering SA, is winning orders as value-conscious customers search for deals online and increasingly shop for clothing and accessories via phones and tablets. The online luxury market will more than double to 15 billion euros by 2016, estimates Forrester Research Inc.

“It is reasonable to expect that Yoox Group will continue to increase revenues and profits in 2013,” the company said in the statement, adding it had more than 1 million active users in the first half.

Yoox shares retreated 1.3 percent to 19.73 euros today in Milan, paring this year’s gain to 66 percent and giving the company a market value of 1.14 billion euros.

Yoox, which designs and manages online stores for more than 30 fashion and luxury goods brands, said it signed yesterday a six-year deal with Kartell SpA for a Web boutique in Europe from the first quarter of 2014. The e-commerce operator has renewed for another five years its partnerships with Aeffe SpA’s Moschino brand, LVMH Moet Hennessy Louis Vuitton SA’s Pucci label and VF Corp.’s Napapijri unit, it said.

In the second-half, Yoox’s single brand business will benefit from the joint venture with Kering as well upgrades to the online stores of a number of long-standing partners, the company said. The multibrand operation, which includes the yoox.com, thecorner.com and shoescribe.com Web stores, will continue to achieve sustained growth, Yoox said.

Investments in operations and technology will continue at a slower pace than in the first half of the year when Yoox’s capital expenditure was 20.3 million euros, it said. Internal initiatives to improve efficiency and ensure tight cost control will also continue, Yoox said.

By: Andrew Roberts; Editors: James Kraus, John Simpson