Wellington, Dec 3 NZPA - The New Zealand sharemarket opened flat, with retailer The Warehouse slipping as it faces possible industrial action in the lead-up to Christmas.

Around 10.15am, the benchmarket NZSX-50 index was up 2.54 points to 3151.99, having edged up just 2.8 points yesterday in quiet trading.

The Warehouse shares were down 3c to 405 early, with the National Distribution Union reporting yesterday that retail staff had voted to strike over their working conditions.

Restaurant Brands shares were down 2c to 160 and Contact Energy fell 2c to 592. Early risers included Pumpkin Patch up 4c to 190, PGG Wrightson up 2c to 60, Hellaby Holdings up 2c to 160 and Telecom up 1c to 247, while Fletcher Building was unchanged on 790.

Among dual-listed shares, ANZ dropped 72c to 2825, Westpac was down 16c to 3110, while Telstra gained 6c to 445.

In the United States, the Nasdaq ended higher as investors grew optimistic about Amazon.com Inc's holiday sales prospects, but the Dow and S&P 500 were little changed after oil prices retreated, pressuring shares of energy companies.

Based on preliminary data, the Dow Jones industrial average fell 0.2 percent to close unofficially at 10,452.68, the Standard & Poor's 500 Index edged up just 0.03 percent to finish unofficially at 1109.24, and the Nasdaq Composite Index gained 0.4 percent to close unofficially at 2185.03.