* Weekly jobless claims data due
* Xerox, Dow Chemical, General Motors report earnings
* Futures down: S&P 8.6 pts; Dow 91 pts; Nasdaq 18.75 pts
NEW YORK, July 25 (Reuters) - U.S. stock index futures fell on Thursday as earnings reports from some major bellwethers triggered concerns about recent gains in equities while ongoing worries of China’s slowdown continued to weigh on investor sentiment.
* Wall Street closed lower on Wednesday but the S&P 500 and the Dow indexes are still near all-time highs. The S&P 500 is up about 20 percent for the year.
* In another big day in earnings, Xerox Corp Dow Chemical Co and General Motors Co are among those that report.
* Shares of Facebook jumped nearly 20 percent in premarket trade to $31.70, a day after the company announced blowout earnings.
* S&P 500 futures fell 8.5 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 fell 67 points, and Nasdaq 100 futures lost 10 points.
* In economic news, weekly jobless claims are due at 8:30 a.m. A Reuters survey of analysts predict 340,000 claims versus the previous week’s 334,000. Durable goods orders data is also due at 8:30 a.m.
* European shares extended losses around midday on Thursday, as mixed earnings and lingering concerns about the pace of growth in China triggered a bout of profit taking following recent sharp gains.
* Chinese stocks suffered their second straight loss on Thursday despite measures from the government to spur the economy, including help for exports and railway investment. Data on Wednesday showed manufacturing in China running at an 11-month low in July.
* Data showing better German business sentiment and the British economy gathering pace came in line with expectations and pointed to only modest growth ahead.