American International Group Inc. earned $2.2 billion in net income for the first quarter of 2013, a 31.2% drop from the same period a year earlier.

In a Thursday statement announcing its results, AIG noted that its first-quarter 2012 results included $3.3 billion of pretax income from investments in AIA Group Ltd., Maiden Lane II L.L.C. and Maiden Lane III L.L.C. that were sold or liquidated in 2012.

AIG's property/casualty operations' net written premiums for the initial quarter of 2013 dropped 4.3% from those of year earlier, declining to $8.44 billion. Underwriting income, however, increased to $231 million from a $180 million loss during the same quarter of 2012.

Total pretax income for property/casualty operations increased 76.3% year-over-year to $1.6 billion.

The insurer's first-quarter combined ratio improved to 97.3% from 102.1% during the same period a year earlier.

“AIG's results this quarter reflect the depth of our global operations, the market's demand for the products and services we offer, and the strong performance of our investment portfolio,” AIG President and CEO Robert H. Benmosche said in a statement announcing the results. “We are pleased with these results and look to continue to build on our successes, especially as we continue to make progress toward achieving our 2015 aspirational goals.”

The priority for 2013 is improving operating fundamentals and reducing costs, Mr. Benmosche said. “Whether this means lowering the cost of capital, re-engineering our systems or focusing on business lines and geographical locations that make strategic sense for our company — reducing expenses and improving operating efficiencies are leading goals of every AIG employee.”

Mr. Benmosche said AIG has already narrowed its core businesses to insurance and retirement services and sees “the potential for further cost savings as we work to transform the corporate structure to support this leaner business. And as a global company with half of our people outside the United States, we are exploring the capabilities, expertise and opportunities where we have operations.”