* Futures down: Dow 78 pts, S&P 8.5 pts, Nasdaq 26.5 pts
By Yashaswini Swamynathan
Oct 26 (Reuters) - U.S. stock index futures were lower for the second straight day on Wednesday following Apple's disappointing quarterly sales and a dip in oil prices.
* Shares of the world's most valuable public company were off 3.4 percent in heavy premarket trading after the company said sales of its flagship iPhones fell for the third quarter in a row.
* Oil prices fell more than 1 percent - Brent crude was on track for the fourth day of declines - after Iraq said it did not want to join an output-limiting deal with OPEC members, and U.S. drillers stepped up work.
* Movement in the markets have largely been dictated by corporate earnings in the past few weeks, but events such as the upcoming U.S. presidential election and the prospects of a U.S. interest rate hike in the coming months have added volatility.
* Wall Street closed lower on Tuesday, after a set of housing and consumer products companies reported weak results and forecasts.
* Still, S&P 500 companies are collectively expected to report a 1.7 percent rise in earnings, snapping a four-quarter streak of profit declines, according to Thomson Reuters I/B/E/S.
* Dow component Boeing will report results before markets open, while electric carmaker Tesla's results are due after the bell.
* A report at 10:00 a.m. ET is likely to show new home sales slipped 1 percent to 600,000 units last month.
* Shares of Edwards Lifesciences fell nearly 10 percent to $102.38 premarket after the medical device maker reported third-quarter sales that missed expectations.
* Weapons maker Northrop Grumman rose 2 percent to $223.96 after the company reported a 16.7 percent jump in quarterly profit.
* Chipotle Mexican Grill dropped 3.9 percent to $390 in light trading after the restaurant chain operator reported a bigger-than-expected drop in quarterly sales at established restaurants.
* Biogen rose 2.8 percent to $294 after the drugmaker reported a 7 percent rise in profit.
Futures snapshot at 6:58 a.m. ET:
* Dow e-minis were down 78 points, or 0.43 percent, with 19,669 contracts changing hands.
* S&P 500 e-minis were down 8.5 points, or 0.4 percent, with 120,756 contracts traded.
* Nasdaq 100 e-minis were down 26.5 points, or 0.54 percent, on volume of 23,186 contracts. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Don Sebastian)