BERLIN, May 12 (Reuters) - German internet service provider United Internet reported lower than expected first-quarter sales on Friday on advertising revenues that fell short, but confirmed its full-year targets based on how the second quarter was progressing.
It also said it had written down the value of shares held in venture capital investor Rocket Internet with an impairment charge of 19.8 million euros ($21.6 million).
Earlier on Friday, the company said it planned to buy a majority stake in mobile operator Drillisch in a staggered stock and cash deal which would boost competition at the low end of the crowded German telecoms market.
United Internet, which is due to release full results on Monday, reported sales of 989.2 million euros and eanings before interest, tax, depreciation and amortisation (EBITDA) of 215 million.
Analysts had expected first-quarter revenue of 1.02 billion euros and EBITDA of 219 million euros, according to a Reuters poll.
"Advertising revenues of United Internet's portals in the second quarter so far are within the budgeted range," the company said in a statement, confirming it still expected sales this year to rise by around 7 percent and EBITDA to increase by about 12 percent. ($1 = 0.9153 euros) (Reporting by Victoria Bryan; Editing by Greg Mahlich)