Accounting firm KPMG says nearly half of the country's listed firms are trading below their book value.
Book value is a measure of the intrinsic net worth of a company and is used by investors to determine whether a company is underpriced or overpriced.
KPMG's research found 45% of NZX firms trade below their book value compared with 21% in 2007.
Factors such as a lack of liquidity and an influential shareholder can sway what KPMG calls the value gap.
But KPMG partner Simon Wilkins says global economic uncertainty and the effect on firms may also prompt differing views on financial performance among investors and the company.
He says economic uncertainty, slow growth and a lack of perspective on what might be to come requires companies to have a greater level of communication with their investors.
Mr Wilkins says if investors have some analysis that enables them to understand why the market values their company in a certain way, it will give them more information and tools to respond to specific situations.
He says the total value of impairment rose to nearly $900 million last year, and he's expecting more due to uncertainty and weak, if any, growth, this year, though that should reduce the gap between stock price and book value.
Mr Wilkins says in recent years 2008 was the high point for impairment and although 2009 and 2010 were somewhat better, in 2011 there was a rebound and a somewhat greater level of impairment.
He says 2012 is likely to be similar to 2011 and there is certainly more impairment to come.