Underlying profit for Meridian Energy slipped by a fifth after it sold its Tekapo hydro stations.
The State-owned power generator reported a net profit of $9.2 million in the six months to the end of December, 89% less than in the same period a year earlier.
When one-off and non-cash items are stripped out, underlying profit fell 20% to $98.9 million.
The fall was mainly due to the sale of its Tekapo hydro stations to Genesis, as part of an asset swap.
The previous period's result was also boosted by a settlement with a major customer, New Zealand Aluminium Smelter.
Revenue rose 12% to $1.2 billion.
Chief executive Mark Binns says it is a sound result in a challenging period.
Meridian increased its customer numbers by 4% in the period, while its Powershop subsidiary boosted its customer base by a quarter.
Meridian's board will announce its decision on an interim dividend before the end of April.