Stock index futures were lower on Wednesday as worries over Europe once again weighed on investor sentiment, putting the S&P 500 on track for a sixth day of losses.

* Muted demand for a German bond auction heightened fears the euro zone crisis would worsen a day after borrowing costs in Spain hit another record high. Concerns about high debt in Europe and the United States have pressured markets. Last week was the S&P's worst in two months, and the index has fallen more than 5 percent in its current string of declines.

* S&P 500 futures fell 8.9 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 81 points, and Nasdaq 100 futures sank 14.75 points.

* The U.S. Federal Reserve plans to run stress tests on six large U.S. banks, including Bank of America Corp and Citigroup Inc , using a hypothetical market shock, including a deteriorating European debt crisis, as part of an annual review of bank health. Bank of America fell 0.9 percent to $5.32 in premarket trading.

* Chinese manufacturing shrank the most in 32 months in November, intensified concerns about a global economic slowdown. Crude oil fell 1.5 percent on fears of reduced demand from the world's No. 2 economy.

* The S&P managed on Tuesday to hold near 1,187, seen as the next technical support and representing the 61.8 percent retracement of the 2011 high to low. The index fell below the 1,200 mark last week.

* Trading volume is likely to be low on Wednesday, the day before the U.S. Thanksgiving holiday, when U.S. markets are closed. That could amplify turbulence, which remains tied to Europe's volatility.

* Investors also awaited a new round of economic data. Initial jobless claims are seen rising by 2,000 to 390,000 in the latest week, while October durable goods orders are forecast to fall 1 percent. Both are scheduled for release at 8:30 a.m. EST.

* In addition, the Thomson Reuters/University of Michigan's final November consumer sentiment index will be released at 9:55 a.m. EST. Economists look for a reading of 64.5, compared with 64.2 in the preliminary November report.

* Deere & Co , one of the world's largest heavy equipment producers, reported quarterly results early Wednesday.

(Editing by Jeffrey Benkoe)