Australia's Whitehaven Coal posted a surprise first-half loss on Thursday, pressured by weaker realised prices that offset robust production across its major operations, sending its shares down more than 6% in early trading.

Whitehaven, the country's top independent coal miner, achieved average coal price of A$189 per ton, about 19% lower than a year-ago levels, pushing revenue down 28% to A$2.48-billion.

"Cyclical price weakness in metallurgical and thermal coal markets continued into the first half of FY26 as a result of ongoing global uncertainties surrounding US tariffs and related trade dynamics," the company said.

The company's Queensland operations, which account for over half the group's operating earnings and include the Blackwater and Daunia coal mines it acquired from BHP in 2024, reported a 58% drop in first-half underlying operating earnings.

Its New South Wales operations also reported a 46% drop in earnings.

As a result, Whitehaven Coal posted an underlying net loss after tax of A$19-million ($13.38-million) for the six-month period ended December 31, reversing from both the Visible Alpha consensus forecast of a A$16-million profit and the A$350-million profit recorded a year earlier.

On a statutory basis, net profit after tax fell 31% to A$69-million.

Whitehaven, however, remains optimistic on the outlook for metallurgical coal prices, citing supply constraints after Cyclone Koji, a category one storm that hit Queensland in January.

The miner also pointed to early indications that the oversupply in the seaborne thermal coal market could ease after Indonesia, the world's largest thermal coal exporter, signalled plans to curb production.

Whitehaven maintained its fiscal 2026 outlook, and said run-of-mine (ROM) coal production and coal sales were trending towards the upper end of its forecast range, while unit costs were projected to land in the lower end.

The miner declared an interim dividend of 4 Australian cents per share and said it plans to spend a further A$32-million on share buybacks over the next six months.