NEW YORK (AFP) - US stocks opened higher Wednesday aiming for a third straight gain as General Motors bolstered sentiment with an improved 2016 earnings forecast and a dividend hike.

Crude oil prices appeared to stabilize, but another fall in the Shanghai stock exchange, by 2.4 per cent, remained a warning of the challenges to equity markets.

About 30 minutes into trade, the Dow Jones Industrial Average was up 44.62 points (0.27 per cent) at 16,560.84.

The broad-market S&P 500 advanced 6.62 (0.34 per cent) to 1,945.30, while the tech-rich Nasdaq Composite rose 7.32 (0.16 per cent) to 4,693.24.

Tech shares led the gains, with Qualcomm up 2.2 per cent and Microsoft 2.1 per cent. But volatile Twitter lost 2.3 per cent.

GM shares jumped 3.0 per cent after the automaker lifted its 2016 earnings forecast, raised its dividend by six per cent, and boosted its share repurchase program by US$4 billion (S$5.7 billion) to US$9 billion.

Oil shares gained on the rebound in crude prices which saw US benchmark WTI crude gain 3.7 per cent at US$31.57 a barrel a day after touching below US$30 for the first time in 12 years.

ExxonMobil shares added 1.6 per cent, Chevron 1.9 per cent, and oilfield services firm Schlumberger 1.3 per cent.

Railroad CSX, one of the first companies to deliver fourth-quarter and full-year 2015 earnings results, lost 2.4 per cent as it reported a 13 per cent fall in income in the final quarter, largely due to a slump in coal shipments.

Rival rail carriers Union Pacific and Norfolk Southern both lost about 0.8 per cent.