Canton-based OneBeacon Insurance Group Ltd. Has reported second quarter net income of $128 million, compared to $23.8 million for the same period a year ago, a 437.8 percent increase.

For the six months ended June 30, net income was $161 million, compared to a loss of $500,000 the year before.

"We are very pleased with our excellent second quarter results," said OneBeacon CEO Mike Miller. "Our book value per share increased by 12 percent reflecting a solid 4 percent investment return and 93 percent combined ratio for the quarter."

The company reduced debt by $78 million during the quarter, contributing to a six point improvement in the debt to total capital ratio since year-end 2008, the firm said in a statement.

Canton-based OneBeacon Insurance Group Ltd. today reported book value per share of $13.51, an increase of 11.5 percent for the second quarter and 14.7 percent through six months, including dividends.

Net written premiums were $498 million for the second quarter, compared to $530 million for the second quarter of 2008. Specialty lines premiums increased by 11.4 percent for the quarter, reflecting new business growth in Entertainment Brokers International Insurance Services, OneBeacon Professional Partners, the collector car and boat business written through Hagerty Insurance Agency, and OneBeacon Government Risks. Second-quarter commercial lines and personal lines net written premiums declined by 9.4 percnet and 18.4 percent, respectively.