WR Berkley has reported a stronger fourth quarter, boosting its 2012 full-year result.

Gross written premium (GWP) was up 16.7% in the quarter to $US1.4 billion ($1.3 billion) from $US1.2 billion ($1.1 billion) in the previous corresponding period.

This gave a full-year GWP of $US5.7 billion ($5.4 billion), up from $US5 billion ($4.7 billion) in 2011.

Fourth-quarter net premiums were $US1.2 billion ($1.1 billion), up from $US1 billion ($958 million).

Full-year net premiums were $US4.8 billion ($4.6 billion), compared with $US4.3 billion ($4.1 billion) in 2011.

CEO William Berkley says core underwriting results continued to improve as prices increased on renewal business.

“The impact of Storm Sandy was mitigated by strategic reinsurance purchases and our fourth-quarter combined ratio was only slightly higher [98.1%, compared with 97%] than the previous year,” he said.

Mr Berkley says higher prices have been reflected in a rise in earned premiums.

The company’s investment portfolio also performed better in 2012, with net investment income up 30% to $US152 million ($145 million).

“Our investment income benefits from particular investment opportunities that produce better than market returns,” Mr Berkley said.

“We realised gains from both our private equity investments and our common stock portfolio, which contributed to our return on equity of just below 17% for the quarter.”

WR Berkley’s investments at December 31 were $US15.6 billion ($14.9 billion), with more than 75% of the portfolio in government and corporate securities.

Of its foreign fixed-interest investments, Australia tops the list, with $US344.3 million ($330.1 million) of government and corporate bonds. The company has only 2.4% of the portfolio invested in equity securities.