The NZX 50 index fell down 49 points, or 1.5% to 3128 on Thursday morning on turnover of $34 million.
Just after midday, Fletcher Building was down 10c to $6.63, while Freightways fell down 11c to $2.91
Hallenstein Glasson was down 16c to $2.53, and Telecom fell 12c to $3.39
In currency markets the dollar was trading at 75.70 US cents, 79.21 Australian, 38.21 pence, 80.90 yen, and 0.4812 euro. The TWI stood at 67.50
Across the Tasman, the Australian 200 index was down 50 points or 1 per cent, to 4961 in early trading.
Earlier, US stocks tumbled, dragging the S&P 500 into a bear market, as worries about more credit losses hurt financial companies.
The S&P closed 20% below its all-time high set in October, making it the last of the three major American stock indexes to fall into a bear market.
All three major stock indexes fell more than 2% on Wednesday.
The Dow Jones industrial average shed 236.77 points, or 2.08%, to 11,147.44, while the Standard & Poor's 500 Index tumbled 29.01 points, or 2.28%, to 1,244.69.
The Nasdaq Composite Index fell 59.55 points, or 2.60%, to close at 2,234.89.
Shares in two large mortgage lenders, Fannie Mae and Freddie Mac, dropped sharply as some investors worried that they would need to raise billions of dollars in additional capital through stock sales, diluting the holdings of current investors.
Merrill Lynch shares fell more than 9%, when Fitch Ratings said it may cut the investment bank's debt rating, given expected ongoing write-downs and diminished prospects for earnings.
Cisco Systems led technology shares lower after its CEO raised fears of an extended economic downturn. On the Nasdaq, Cisco shares fell 5.7% percent to $US21.58.