Shares in Fletcher Building, the country's biggest listed company, have taken a hit after it slashed its full-year earnings guidance by more than $100m.
The building company has blamed the cut on expected losses on major construction contracts.
Its shares were placed in a trading halt on Friday, pending today's announcement.
The company was now forecasting its full-year underlying earnings to be between $610 and $650 million, compared with previous guidance of $720 to $760 million.
By 10am, shares in the company had fallen 12 percent, or $1.12, to $8.10 each, the lowest since mid-July last year.
That dragged the overall NZX down by nearly 1 percent.
Fletcher Building said the losses were in its buildings and interiors unit of the construction division.
But it would not name the projects because of customer confidentiality.
Chief executive Mark Adamson said that unit's performance has got worse.
"It is very disappointing that the review of the B+I business unit has found weaker performance than we had previously understood," he said.
The company disappointed investors in the half-year with a flat profit because of losses related to a construction contract.
But Fletcher Building said trading in its other divisions remained in line with previous expectations.
Shares in the company resumed trading this morning.