(Sharecast News) - Shares in German online fashion retailer Zalando dropped sharply on Tuesday after second-quarter results and full-year guidance disappointed investors.

Gross merchandise volumes totalled €4.92bn in the second quarter, while group revenues reached €3.42bn, with both measures rising nearly 21% year-on-year.

However, growth still came up short of analysts' expectations, missing the consensus forecasts of €4.94bn and €3.50bn, respectively.

Adjusted EBIT rose to €204.8m from €185.5m, shy of the €215m expected by the market, with the adjusted EBIT margin slipping to 6.0% from 6.5%.

Looking ahead, the firm said GMV and revenue growth for the full financial year would likely be in the lower half of its previous 12-17% range. Adjusted EBIT guidance was narrowed to €680m-720m from €660m-740m.

"Zalando's view of second-half trading dynamics is unchanged, and the full-year guidance refinement reflects the first half already delivered and not a change in expectations for the remainder of the year," the firm said in a statement.

The company expressed confidence in recent investments into AI, such as the launch of AI-powered fashion and lifestyle content studio SCAYLE STUDIOS, which moves brands from sample to production-ready imagery significantly faster, shortening the time-to-market by more than 95%, it explained. It has grown to over 100 live brands.

"Our fast-scaling AI capabilities are already delivering measurable benefits in driving both growth and efficiency across B2C and B2B," said co-chief executive Robert Gentz.

"Innovations like our AI-powered SCAYLE STUDIOS and the upgraded Zalando Assistant are fundamentally transforming how our partners operate and how our customers discover fashion."

Zalando shares were down 13.9% at €25.06 by 1305 BST.