* Apple down after rev forecast misses estimates
* TripAdvisor, Priceline fall after Goldman Sachs downgrade
* Boeing drops after weak forecast
* Futures down: Dow 66 pts, S&P 4.5 pts, Nasdaq 18.5 pts (Adds details, comment, updates prices)
By Abhiram Nandakumar
Jan 27 (Reuters) - U.S. stock indexes were set to open lower on Wednesday after oil prices retreated yet again and Apple forecast its first revenue dip in more than a decade.
Apple's shares were down 3.2 percent at $96.85 premarket after the company also posted its slowest-ever rise in iPhone shipments.
Crude prices resumed their decline after an unexpected rise in U.S. inventories erased optimism about the possibility of the world's top producers coming together to address a massive glut.
Global stocks took a hit from the slump in oil, as anxious investors await the U.S. Federal Reserve's statement on monetary policy due at 2:00 p.m. ET (1900 GMT).
"Markets are not happy and they haven't been happy the whole month," said Omar Aguilar, chief investment officer of equities at Charles Schwab Investment Management in New York.
"Generally, for the whole month, people have been concerned about global growth, China, and really, really concerned about oil," he said.
While an interest-rate hike is not expected today, investors will be keen to see the Federal Reserve's reaction to the current turmoil in global markets.
At 8:31 a.m. ET, Dow e-minis were down 66 points, or 0.41 percent, with 53,594 contracts changing hands. S&P 500 e-minis were down 4.5 points, or 0.24 percent, with 271,254 contracts traded. Nasdaq 100 e-minis were down 18.5 points, or 0.44 percent, on volume of 49,827 contracts.
With earnings season in full swing, investors are likely to cheer companies that report revenue growth in turbulent conditions.
Boeing dropped 6.6 percent to $119.60 after the company's earnings forecast missed expectations.
AT&T was down 2.6 percent at $34.48 and Textron was down 7.2 percent at $35 after both companies posted revenue below estimates.
TripAdvisor was down 5.9 percent, Priceline was off 3.5 percent and Expedia 2.5 percent, after Goldman Sachs downgraded travel-related stocks.
Among the few gainers, Biogen was up 5.4 percent at $273.90 after its profit beat expectations.
Tech majors Facebook, Qualcomm and eBay are slated to report after the close.
Data is expected to show U.S. single-family home sales rose for the third straight month in December. The report is due at 10:00 a.m. (Reporting by Abhiram Nandakumar in Bengaluru; Editing by Anil D'Silva)