US stocks have edged up in opening trade as strong earnings from UPS and others offset disappointing results from Amazon.

Five minutes into trade, the Dow Jones Industrial Average stood at 16,687.44, up 9.54 points (0.06 per cent).

The broad-based S&P 500 added a scant 0.53 (0.03 per cent) at 1,951.35, while the tech-rich Nasdaq Composite Index rose 5.47 (0.12 per cent) to 4,458.26

Amazon shares sank 7.3 per cent as its third-quarter loss rose ten-fold to $US437 million due to the costs of product launches including new phones, tablets and television programs.

UPS gained 1.7 per cent on earnings above expectations and its forecast of an 11 per cent jump in shipments in December.