US-based insurer The Chubb Corporation has reported a net income of $452m, or $1.60 diluted earnings per share, for the fourth quarter of 2011, compared to $620m, or $2.02 diluted earnings per share, for the same period in 2010.

Operating income, excluding investment gains and losses, was $460m for the fourth quarter of 2011, compared to $519m for the same period a year ago.

Net written premiums increased 4% to $3bn from $2.9bn for the same period in the previous year.

Losses and loss expenses were $1.74bn, compared to $1.59bn for the same period in the last year.

Investment income slipped to $391m, compared to $396m in the year ago quarter.

Chubb Corporation chairman, president and CEO John Finnegan said that the fourth quarter was especially encouraging as the commercial rate environment continued to improve.

"We secured an average renewal rate increase of 6% in our US standard commercial business, and average renewal rates in our US professional liability business turned positive for the first time in two years," added Finnegan.