WR Berkley gross written premium (GWP) rose 10.1% in the December quarter, with the US-based company noting “further compelling evidence” of an improving market.

GWP increased to $US2.03 billion ($3.02 billion), but net investment income fell and total expenses increased compared to the corresponding period last year.

Net profit for the three-month period declined to $US119.3 million ($177.4 million) from $US132.4 million ($196.9 million).

“Rate increases accelerated, which is the natural progression in a hardening market, to approximately 9% excluding workers’ compensation,” the company said. “As rate increases remain robust, we expect continued opportunities to grow the top line.”

The fourth quarter was challenging for the company’s alternative investments, but WR Berkley says they are expected to produce above-average long-term returns and will remain a core part of its investment strategy.

Full-year GWP rose 7.3% to $US8.26 billion ($12.28 billion), while earnings increased 6.4% to $681.9 million ($1 billion).