Tower Group has reported a net loss attributable to common shareholders of $28.2m or $0.73 per share for 2012, compared to a net income of $60.5m or $1.48 per diluted share, during the same period last year.

The operating loss stood at $27.9m or $0.72 per share, compared to an operating income of $56.3m or $1.38 per diluted share during the corresponding period prior year.

For the year ended on 31 December 2012, its net premiums earned rose by 8% to $1.72bn, from $1.59bn during the comparable period earlier year.

Gross premiums written and managed stood at $1.97bn, up by 8.8% from $1.81bn during the same period last fiscal.

Tower Group president and CEO Michael Lee said that 2012 was disappointing as the impact of Superstorm Sandy in the fourth quarter and the reserve charge in the second quarter combined to yield the first annual operating loss since 2004.

Net investment income was $127.2m, compared to $126.5m; while operating return on average equity (ROE) excluding the impact of catastrophes and reserve development was 10.1% in 2012 compared to 11% in 2011.

Tower Group provides diversified property and casualty insurance products and services through its operating subsidiaries.