US pre-open: North Korea and oil prices give US markets the jitters

US stock futures were set to plunge on Wednesday, hit by falling oil prices and tensions over North Korea.

The Dow Jones Industrial Average was expected to open down around 241 points, while the S&P 500 and the Nasdaq were set to begin the session 31 and 79 points lower, respectively.

The economic calendar was rather full, with the Federal Reserve minutes from December due out at 1900 GMT, the Markit US PMI December numbers out at 1445 GMT, the US Non-Manufacturing Composite as well as factory orders figures due at 1500 GMT, and the US trade balance for November released at 1330 GMT.

North Korea shakes Asian markets, while China turns things around

Elsewhere, stocks in Asia were shaken by North Korea's apparently successful testing of a hydrogen bomb, although hints of some government help stabilised Chinese markets further.

China staged an about-face from its dire start to the week, with the Shanghai Composite index gaining 2.25%.

It had lost around 7% since the open on Monday, due to concerns about a slowdown in the country's economy, a weaker yuan and the impending lift of a no-sell order placed on major shareholders during the summer crash.

Both analysts and traders in the region pointed the finger at China's crack "National Team" for the Wednesday gains. The team is a group of state-owned funds tasked with holding up the market, and the gains were seen as a sign that they were ready to step in should losses become worse.

The regulator in Beijing also signalled on Tuesday that it was going to regulate selling among big shareholders, easing fears of mass selling on Friday, when the unloading ban expires.

Analysts understood the regulator's comments as meaning authorities would disallow aggressive unloading, and were armed and ready should the market destabilise. It was also unclear whether the ban would be lifted on Friday, or remain in place until new rules are figured out.

European stocks fell on Wednesday, with shares of basic resources outfits pacing the decline.

Oil prices were in the red again, with Brent down 3.62% to $35.10 a barrel and West Texas Intermediate down 2.59% to $35.04.

The dollar was up against the pound, rising 0.15%, while it dropped 0.06% against the euro and 0.5% against the yen. Spot gold was up 0.67% to $1,084.94.

In company news, Apple plunged 2.4% before the bell after reports late on Tuesday that it plans to scale back production of iPhones, partly reflecting recently lower than expected sales.

Pioneer Natural Resources also dropped 7.7% in pre-market trades after it announced a 10.5m share offering.