W.R. Berkley Corp. reported $116 million net income for its 2013 second quarter, up more than 6 percent from $109 million net income posted one year ago.

The net income for the first six months of 2013 came in at $233 million, a 4.7 percent decline from $244 million a year ago.

The insurer said average rates on renewed policies increased 6.5 percent in the second quarter — with 43 of its 47 underwriting units achieving additional rates. The company said the renewal retention ratio is remaining at around 80 percent.

“When we look at the marketplace, we are convinced that — at a minimum — rate increases will remain or increase from here,” said Chief Operating Officer William Robert Berkley. During an earnings conference call, he spoke of “the fundamental reality of the economic model of the industry.”

The lower interest rates and its impact on the industry’s investment returns is “here and coming into focus very quickly,” he said. “And that is putting further pressure on the marketplace to look for ways to increase underwriting margins.”

W.R. Berkley CEO William R. Berkley said that his company’s cumulative rate increases since 2010 are in excess of 18 percent, and the premium volume has grown by over 30 percent in the past two years.

CEO Berkley also said during the earnings conference call that there is “no new entrant in our space.” Also commenting on Berkshire Hathaway Specialty Insurance — the new commercial P/C insurance unit of Berkshire Hathaway — he said “they are in a lot of people’s space, but generally not in our space.”

“They may come in some of our space, but our space is much more people-intensive and broker-intensive,” he said. “They have a few good people writing large risks. Our biggest risk is probably not big enough to be their smallest risks.”

Net premiums written for the 2013 second quarter were $1.342 billion, up 12.7 percent from $ 1.191 billion a year ago. Net premiums written for the first half of 2013 were $2.719 billion, up 13.5 percent from $2.395 billion a year ago.

The GAAP combined ratio for the second quarter was 96.6 percent, improving from 98.2 percent one year ago. The GAAP combined ratio for the first half of 2013 was 95.6 percent, improving from 97.4 percent one year ago.

Net investment income for the second quarter was $144 million, down 11 percent from $161 million a year ago. Net investment income for the first six months was $280 million, down 12 percent from $319 million a year ago.

CEO William R. Berkley said the second quarter’s results were driven by higher underwriting margins and a declining expense ratio and the benefits from improved underwriting results more than offset the decline in investment income.

“Our company continues to improve its relative competitive position while avoiding the extreme volatility impacting the general marketplace,” the CEO said. “We expect our returns to increase as our earned premium reflects the recently improved pricing levels.”

He also expressed his concern that the investment yields will remain under pressure. “The current bond market yields continue to impact our investment income. In spite of the recent improvement in yields, new purchases result in substantially lower returns than maturing securities,” he said.

“We continue to search for attractive opportunities but we are still unwilling to extend the duration or diminish the quality of our portfolio. Overall, yields will remain under pressure, although we anticipate benefiting from capital gains through the balance of the year,” he said.