Private health insurer NIB warned full-year earnings will fall as much as 10 per cent this year due to mounting losses in its New Zealand business, where soaring claims are rendering it unprofitable over the December half.

NIB’s guidance for underlying operating profit of between $235 million and $250 million for the year to June 30, 2025, is lower than the $257.5 million reported last year and below analysts’ median forecast of $261.5 million, according to Bloomberg data.