The local index has dropped 3.1per cent this month as investors have grown increasingly wary about the US Federal Reserve hiking that country's interest rates, which would make the yields of NZ listed companies less attractive. However, the index is still up 12.6 per cent this year.
"I think investors are a little bit nervous with what's happening overseas. We've had some small sell-offs in the American market, and I think investors are being a bit cautious at the moment," Williamson said. "This correction is relatively healthy."
Summerset Group led the index, up 1.9 per cent to $4.86. Contact Energy gained 1.7 per cent to $4.90 and Xero rose 1.7 per cent to $17.89.
NZ Refining Co was the worst performer, down 2.5 per cent to $2.34, while Auckland International Airport dropped 1.8 per cent to $6.62, Tower fell 1.6 per cent to 90.5c and Trade Me Group shed 1.5 per cent to $5.24.
Outside the benchmark index, Steel & Tube Holdings advanced 3.3 per cent to $2.22. It will buy Composite Floor Decks, which supplies and installs composite floor decking, for $13.3m, with a further $3m possible based on its performance in the next two years.
Scott Technology gained 4.8 per cent to $2.20. On Thursday, it reported a record $11m in full-year pre-tax profits.