New Zealand shares dropped, led lower again by A2 Milk Co while Fletcher Building and CBL Corp rose.

The S&P/NZX 50 index fell 17.94 points, or 0.2 per cent, to 8065.12. Within the index, 22 stocks fell, 18 rose and 10 were unchanged. Turnover was $173.3 million.

A2 Milk fell 3.2 per cent to $8.15. The stock has bounced around the past two days, falling as low as $7.45 on Wednesday before rising back to $8.42 on Thursday, but is still up 295 per cent this year.

"A broker downgraded their recommendation two days ago. It's gone up significantly in the last while and pulled back two days ago quite sharply," said Craig Stent, executive director and head of equities at Harbour Asset Management.


"It seems it was a lot of small parcels going through, particularly in Australia, so that tells you that it's more retail-oriented [investors] who have been selling it then buying it back on Thursday. Outside of that there has been no real news flow. It's only back to where it was at the end of last month - it's done a big round trip."

Spark dropped 2 per cent to $3.64, Contact Energy fell 1.2 per cent to $5.77 and Trade Me dipped 1.1 per cent to $4.32.

Fletcher Building propped up the index, rising 2.6 per cent to $7.18. The stock has fallen 34 per cent this year.

CBL Corp gained 2 per cent to $3.01, having traded as high as 5 per cent during the session.

"There was a big line of stock through two or three days ago, and that's been overhanging the market. Now that's been cleared, so we're seeing a bit of a pop in the share price," Stent said. "It has been particularly weak for a while. The other news is that the CFO is resigning - he's there another six months - not that his resignation is the reason they're up 5 per cent, but it's another item of news flow."

Outside the benchmark index, Colonial Motor Co rose 0.3 per cent to $7.64. The motor vehicle distributor, which listed on the NZ stock exchange in 1962, is cautious about forecasting in the year ahead despite its strong returns in 2017 and continued demand for new vehicles.

At its 99th annual meeting in Wellington yesterday, chair Jim Gibbons said it was difficult to give accurate forecasts from month to month, let alone six months ahead, but he noted the first quarter to September 30 had improved on last year and produced an excellent result.