Ambac Financial Group Inc. reversed a fourth-quarter loss thanks to lower losses from claims and expenses, and higher income from investments.

The New York-based guarantee insurer, which is currently under bankruptcy protection, reported Q4 net income of $145 million, compared to a prior-year net loss of $963 million.

For the year, the net loss decreased from $1.96 billion in 2011 to net loss of $257 million.

Improvements in the company’s performance in part came from an increase in net investment income of 1 percent to $93 million. The company reported a net benefit in loss and loss expenses for Q4 of $36.7 million compared to $803.6 million net loss in 2011. The net benefit resulted from lower estimated losses for second lien, residential-mortgage-backed securities and certain student-loan transactions.

Ambac said reorganization costs under the Chapter 11 bankruptcy for Q4 were close to $3 million compared to $10 million for the prior year due to lower professional fees it had to pay following adoption of its reorganization plan in March of 2012.