AMP New Zealand Office Trust says the value of its portfolio is expected to plummet 15%, or almost $240 million, for the year to June.
The country's largest listed commercial property investor says its portfolio declined just over 5% in the June quarter.
Chief executive Robert Lang says the credit crisis, the economic recession and its effect on the investment market has had a significant impact on most of its assets. He says growth has stalled, and lower recruitment and employment has reduced demand for new office space.
Mr Lang says the company is hopeful the worst is behind it.