Allied World Assurance Co. Holdings A.G.’s net income for the second quarter of 2016 rebounded to $153.4 million compared with net income of $9.5 million during the same period in 2015, the insurer reported, reflecting in large part improvements in investment income.

The growth in net income also reflected growth underwriting income as well as lower catastrophe losses, Zug, Switzerland-based Allied World said Tuesday in its earnings report. In contrast, second-quarter 2015 net income had been battered by catastrophe and noncatastrophe losses, as well as investment losses.

“Overall, I’m very pleased,” said President and CEO Scott Carmilani during a conference call Wednesday morning. Mr. Carmilani said that, among other things, the company has “focused on our volatility” in catastrophe exposures.

The company is selectively expanding some lines of business while shrinking others, Mr. Carmilani said during the conference call. For example, Allied World’s financial supplement showed drops in gross written premiums for property in all of its three business segments — North American insurance, global markets insurance and reinsurance — while showing increases in the specialty business in both North American insurance and reinsurance.

Looking at the market as a whole, Mr. Carmilani said, “the U.S. remains the strongest rate environment globally.”

Net premiums for the second quarter of 2016 fell 4.2% from those of the same period in 2015 to $578.1 million, Allied World said.

The company sustained $20.9 million in catastrophe losses during the second quarter of 2016, compared with $25.0 million during the same period a year earlier. Underwriting income, however, reached $45.4 million, up from $5.9 million during the second quarter of 2015.

The company’s combined ratio improved to 92.5%, compared with 99.2% in the second quarter of 2015.

Investment income increased 30.6% to $55.8 million, while realized investment gains for the quarter rose to $74.5 million from a loss of $20.2 million for the comparable quarter in 2015.

Total revenue grew 10.2% to $738.5 million over the prior-year period,

In a research note, analyst Amit Kumar of Macquarie Capital (USA) Inc. noted that Allied World had beaten earnings through lower catastrophe losses, higher-than-expected favorable development, and higher investment income.

For the first six months of 2016, net income rose 70.0% from that of the first six months of 2015 to $227.5 million. Net written premiums dropped 6.8% to $1.28 billion. Investment income for the six month period rose 25% to $109.1 million, and realized investment gains rose to $93.4 million from $24.8 million during the same period a year earlier. The combined ratio, however, deteriorated slightly to 94.3% from 94.0%. Total revenue for the six month period rose 4.7% to $1.39 billion.