* Sees ad market cooling off in Q4, to weigh on sales growth
* Expects 2010 EBITDA margin around Q1-Q3 level of 24 percent
* Q3 net up, sales jump on TV ad recovery
* Shares reverse early gains
(Adds press conference comments, updates share price)
By Agnieszka Barteczko and Adrian Krajewski
WARSAW, Oct 26 (Reuters) - Eastern Europe's top listed broadcaster TVN expects a cooler final three months of the year after a recovering advertising market and lower finance costs lifted third-quarter net profit by a surprise 5 percent.
TVN shares reversed earlier gains to trade just over 1 percent down at 1124 GMT as the Polish broadcaster's Chief Executive Markus Tellenbach said he expected advertising market growth to be slower than it was in the last two quarters.
"We believe that the bullish recovery (for the ad market) in the second and third quarter won't be continued in the fourth quarter," Tellenbach told a news conference.
"Cooling off doesn't mean a negative trend but a pace slower than in the second and third quarter. For the whole year we still expect the market to show growth at lower single-digit pace."
The group expects revenue growth in the last three months of the year to be around 15 percent, in line with the first three quarters on a comparable basis, after the top line grew by a fourth to 534 million zlotys ($190 million).
TVN, which also controls Poland's top portal Onet.pl and pay-TV platform 'n', also expects a 2010 EBITDA (earnings before interest, tax, depreciation and amortisation) margin of close to the 24.4 percent achieved in the first nine months.
"Their cautiousness runs against positive third-quarter results," Raifeisen analyst Dominik Niszcz said. "Maybe one should wait until next year for more positive advertising market trends."
Third-quarter net profit rose 5 percent to 61 million zlotys, far exceeding market expectations of a 40 percent fall, on lower than expected financial costs relating to the group's euro-denominated debt.
TVN took heart from the TV advertising market's 10 percent rise in the July-September period, with revenue from the online segment and the 'n' platform adding steam.
Analysts expect 'n' to be a drag in the last quarter of the year after two straight quarters of positive EBITDA, as pay-TV platforms use the holiday season to lure new customers with hefty discounts.
In order to support 'n', expected to start showing positive cash-flow next year, TVN has signed a long-term cooperation deal with Poland's top telecom TPSA to add broadband Internet to the platform's offer. (Writing by Adrian Krajewski; Editing by David Cowell and Sue Thomas)