However, while the current bull market in NZ equities has been long in duration, it hasn't achieved the magnitude of much shorter, sharper upturns in the 1980s that led up to the 1987 crash.
In the report, Green and Turnbull noted that the S&P/NZX 50 had notched up an average annual gain of 15.4 per cent over the past five years, well above its more modest 10-year average of 8 per cent.
This raised concerns around the "durability" of recent gains.
The report also noted that the market's 12-month forward price-to-earnings ratio - a measure of how cheap or expensive stocks are - of 21.6 times was roughly 35 per cent above its 10-year average of 16.1 times.
Risks facing the market included earnings or dividend disappointments and a sharp rise in domestic bond yields from their historic lows, according to First NZ.
But the report added that while the market was trading at stretched valuations, short and long-term interest rate settings remained supportive and there was an absence of a clear "sell signal".