* Futures up: Dow 269 pts, S&P 33.5 pts, Nasdaq 77 pts
By Tanya Agrawal
Aug 26 (Reuters) - U.S. stock index futures were sharply higher on Wednesday, a day after a rally on Wall Street fizzled as concerns about China's economy overwhelmed a bout of bargain-hunting.
* The Dow Jones industrial average has lost 10.71 percent in the past six trading days, while the S&P 500 has dropped 11.71 percent and the Nasdaq composite 11.5 percent.
* "These type of swings are typical when the market behaves in a way that is a real test of nerves and there is a lot of ongoing uncertainty," said Peter Cardillo, chief market economist at Rockwell Global Capital in New York.
* Futures extended their gains after data showed that applications for U.S. home mortgages edged up last week.
* Investors will be looking for clues on the timing of a U.S. interest rate hike when Federal Reserve Bank of New York President William Dudley speaks on the regional economy.
* Data scheduled for Wednesday includes durable goods orders at 8:30 a.m. ET (1230 GMT), expected to have increased 0.4 percent in July, down from June's 0.9 percent rise.
* The Shanghai Composite Index ended down for the fifth straight day, underscoring fragile confidence and deep doubt over whether the Chinese central bank's cuts in interest rates and reserve ratios on Tuesday could stabilize the economy.
* China's economic downturn and global market turmoil have also created fresh uncertainty over whether the U.S. Federal Reserve will begin raising interest rates this year.
* The dollar index, which touched a 7-month low earlier in the week, was down 0.2 percent.
* Oil stabilized, but prices stayed near 6-1/2-year lows, with U.S. crude oil still trading below $40 per barrel.
* Google shares were up 3 percent at $630.71 in premarket trading after Goldman Sachs raised its rating to "buy" from "neutral" and added it to its conviction buy list.
* Cameron International soared 40.7 percent to $59.75 after Schlumberger, the world's No.1 oilfield services company, said it would buy the oilfield equipment maker in a deal valued at $14.8 billion. Schlumberger fell 2.1 percent to $71.
Futures snapshot at 7:40 a.m. EDT (1140 GMT):
* S&P 500 e-minis were up 33.5 points, or 1.79 percent, with 504,139 contracts traded.
* Nasdaq 100 e-minis were up 77 points, or 1.91 percent, on volume of 80,359 contracts.
* Dow e-minis were up 269 points, or 1.71 percent, with 52,329 contracts changing hands. (Additional reporting by Sweta Singh; Editing by Saumyadeb Chakrabarty)