The benchmark S&P/NZX 50 Index slid 82.918 points, or 0.65 per cent, to 12,590.31 on Tuesday, following a 0.5 per cent drop on Monday.
The a2 Milk Company fell 4 per cent to $6.41, taking its slide so far this week to more than 10 per cent.
Investors are concerned about regulatory creep in China across the technology, property and education sectors, said Craigs Investment Partners investment adviser Peter McIntyre.
“We have seen the Chinese government regulate more around those three sectors, and maybe some investors are looking to reduce exposure to some companies that have had or will have exposure directly to China,” McIntyre said. “Obviously A2 is exposed to that Chinese market.”
The infant formula sector has been struggling after Covid-19 disrupted trade to the key Chinese market.
Shares in A2 Milk have lost 69 per cent of their value over the past year, although they have recovered from their low of $5.42 touched in mid-May.
Also weighing on the sharemarket was a fall in the largest listed stock, medical device maker Fisher & Paykel Healthcare, which slid 1.8 per cent to $31.86.
Mercury fell 2.5 per cent to $6.68, Contact Energy slipped 1.8 per cent to $8.22, and Meridian Energy edged down 1.1 per cent to $5.28.
Asian stock markets were mostly higher on Tuesday as investors looked ahead to a Federal Reserve report for an update on when United States stimulus might start winding down.
Sharemarkets in Shanghai, Tokyo, Seoul, Sydney, Singapore and Jakarta advanced, while Hong Kong retreated.
On Monday, Wall Street’s benchmark S&P 500 index rose to a new record, shrugging off worries about the spread of the coronavirus’s more contagious Delta variant.
Investors are awaiting the Fed report on Wednesday for signs of the central bank’s level of concern about inflation and when it might start rolling back easy credit and other economic stimulus.
Minutes of the Fed meeting in June showed board members discussed how and when they might reduce monthly bond purchases that inject money into the financial system.
– With AP