U.S. stock futures flat as North Korea tensions, Hurricane Irma weigh

U.S. stock index futures were little changed on Wednesday as investors curbed their risk appetite due to simmering tensions on the Korean peninsula and concerns that the Category 5 hurricane Irma could hit the United States. 

The S&P 500 stumbled to its biggest single-day loss in about three weeks on Tuesday after North Korea conducted its most powerful nuclear test yet, over the weekend, triggering a dramatic escalation of its stand-off with the United States. 

Gold rose to near one-year highs, while the bond market rallied, with the 10-year yield hitting a near 10-month low on Tuesday, as investors sought safety amid uncertainties. 

Hurricane Irma is expected to become the second powerful storm to thrash the U.S. mainland in as many weeks but its precise trajectory remained uncertain. Hurricane Harvey killed more than 60 people and caused damaged estimated as high as $180 billion when it hit Texas late last month. 

Oil prices rose on Wednesday as many refineries, pipelines and ports that were knocked out by Harvey reopened.

The Federal Reserve issues its Beige Book at 02:00 p.m. E.T. (1800 GMT), a round-up of anecdotes on the health of the economy, that will likely provide further evidence about the strength of the economy. 

Three Fed policymakers on Tuesday expressed doubts about further rate hikes, with one influential policymaker calling for a delay in raising U.S. interest rates until the Fed is confident inflation will rebound. 

A Commerce Department report is likely to show trade deficit widening to $44.6 billion in July from $43.6 billion in June. The data is expected at 8:30 a.m. ET. 

Also expected is a report from the Institute for Supply Management at 10:00 a.m. ET on index of nonmanufacturing activity for August. 

Shares of Hewlett Packard Enterprise (HPE.N) were up 2.56 percent in premarket trading after the company reported a surprise rise in quarterly revenue.