* Futures down: Dow 261 pts, S&P 32.5 pts, Nasdaq 78.25 pts
By Tanya Agrawal
Jan 6 (Reuters) - U.S. stock index futures were sharply lower on Wednesday as China allowed its currency to weaken further and oil prices fell to their lowest in more than 11 years.
* North Korea's announcement that it had successfully conducted a test of a hydrogen bomb added to geopolitical worries stirred by a row between Saudi Arabia and Iran.
* The People's Bank of China on Wednesday set the yuan's official midpoint rate at its weakest level in 4-1/2 years, while a PMI survey showed services sector activity expanded at its slowest rate in 17 months in December in the country.
* U.S. stocks closed slightly higher on Tuesday, stabilizing after a weak start to the new year, though investor nervousness stayed high.
* The year was off to a shaky start after poor economic data from China reignited fears of a global economic slowdown and as the dip in oil prices show no signs of abating.
* Investors will also keep an eye out for a host of U.S. data scheduled to be released during the day. The Federal Open Market Committee issues minutes from its meeting of Dec. 15-16, where it raised interest rates for the first time in nearly a decade.
* The ADP National Employment Report for December is likely to show an addition of 192,000 jobs. The data, expected at 8:15 a.m. ET (1315 GMT), comes ahead of a more comprehensive non-farm payroll report on Friday.
* The Commerce Department issues international trade data for November at 8:30 a.m. ET. The trade gap is likely to widen to $44 billion.
* Shares of Apple were down 2.44 percent at $102.71 in premarket trading, a day after the Nikkei reported that the company is expected to cut production of its latest iPhone models due to mounting inventories.
* Valeant Pharmaceuticals was down 6.9 percent at $93.87 after reports the company will appoint an interim chief executive officer to replace Michael Pearson, who is hospitalized.
* Fitbit was down 2.5 percent at $24.30 after the wearable fitness device maker's new smartwatch failed to impress.
Futures snapshot at 6:35 a.m. ET:
* S&P 500 e-minis were down 32.5 points, or 1.62 percent, with 287,698 contracts traded.
* Nasdaq 100 e-minis were down 78.25 points, or 1.75 percent, on volume of 52,600 contracts.
* Dow e-minis were down 261 points, or 1.53 percent, with 57,419 contracts changing hands. (Reporting by Tanya Agrawal; Editing by Saumyadeb Chakrabarty)