State-owned Meridian Energy has warned its full-year profit could slump because of record low inflows into its hydro lakes and transmission constraints.
First-half profit for the company, earmarked for partial sale by the Government, slid 20 per cent and it says the second half could be worse.
Chief financial officer Paul Chambers said the cut to earnings of the "sort of magnitude" forecast would be unusual.
Commenting on its third-quarter results, he said the company was looking to cut costs and defer spending.
"Clearly nobody's going to be getting a bonus with this sort of result."