* Q2 pretax up 27 pct to 334 mln euros, beats poll forecasts
* Combined ratio 89.9 percent vs 90.7 percent year earlier
* 2010 combined ratio seen between 92 and 94 percent
* Shares rise 1.8 percent, most traded on Helsinki bourse
(Adds analyst comment, updates shares)
By Georgina Prodhan and Terji Kinnunen
HELSINKI, Aug 11 (Reuters) - Finnish insurer Sampo reported a 27 percent increase in second-quarter pretax profit to 334 million euros ($439 million), beating expectations, thanks to lower claims at its non-life unit.
The results confirmed an upbeat trend among European insurers as an economic rebound helps boost premiums.
Sampo said on Wednesday its second-quarter combined ratio, a key measure of underwriting profitability which expresses costs and claims expenses as a proportion of premium income, fell to 89.9 percent from 90.7 percent a year earlier.
Shares in Sampo rose 1.8 percent to 19.69 euros by 0836 GMT, outperforming a 0.9 percent dip in the European insurance index . Sampo was the most traded stock on the Helsinki bourse,, a position normally held by Nokia.
"The second-quarter results were good, they surprised positively," said Kimmo Ramo, analyst at Evli Bank said.
"The better-than-expected pretax profit was boosted by the P&C (property and casualty) insurance business, in which the combined ratio was much better than forecast."
Sampo narrowed its full-year guidance, saying it expected the combined ratio to be between 92 and 94 percent. Sampo had targeted a 2010 ratio below 95 percent.
Sampo repeated it expected a good 2010 result after the second quarter, in which its pretax profit beat all forecasts in a Reuters poll of 11 analysts.
At Sampo's P&C unit, If, pretax profit rose 27 percent to 208 million euros.
"Claims development in If P&C was favourable in the second quarter of 2010 after the extreme winter conditions of the first quarter," Sampo said in a statement.
Reported pretax profit was boosted by 106 million euros from its stake in Nordea Bank. Sampo said it owned 20.5 percent of Nordea as of June 30. It books its share of Nordea results as an associated company.
($1=.7604 Euro)
(Editing by Michael Shields)