NEW YORK ( TheStreet) - Travelers ( TRV) reported third-quarter operating earnings of $332 million, or 79 cents per share, down from a operating profit of $858 million, $1.81 a share, in the same period last year. The average estimate of analysts polled by Thomson Reuters was for operating earnings of 99 cents a share. Net written premiums for the quarter were up 4%, to $5.67 billion from $5.46 billion in the same period last year. The insurers' combined ratio - a key indicator of underwriting profitability -- was 104.5%, up from 90.6% in the third quarter of 2010. "With third quarter earnings being meaningfully impacted by a number of significant catastrophes, including Hurricane Irene and Tropical Storm Lee, the strength of our business enabled us to generate net income and grow book value per share to $60.98, up 4% from year-end 2010," said Travelers CEO and chairman Jay Fishman in a statement.