S&P 500 futures were up 0.13%, Dow Jones Industrial Average futures added 0.1%, and Nasdaq futures gained 0.18%.
Apple climbed 1.6% in premarket trading after iPhone sales in China boosted overall quarterly revenue. The tech giant earned $1.96 a share in its recent quarter, above estimates of $1.88. Revenue jumped 22% to $51.5 billion and beat forecasts. The company sold 48.04 million iPhones during the quarter, only two days of which included sales of the new iPhone 6S and 6S Plus.
Twitter (TWTR) - Get Report slumped 10% in premarket trading after releasing a disappointing sales outlook. The social network expects fourth-quarter revenue in the range of $695 million to $710 million. Analysts had expected an average $741 million. Twitter bested third-quarter estimates on the top- and bottom-line.
Walgreens Boots Alliance (WBA) - Get Report moved higher in premarket trading after agreeing to acquire rival Rite Aid (RAD) - Get Report for $9 a share. The all-cash deal combines the second- and third-largest drugstore chains in the U.S.
Separately, Walgreens reported a better-than-expected quarter, boosted by the inclusion of Alliance Boots sales after its acquisition closed. Net income of 88 cents beat estimates by 7 cents, while revenue of $28.52 billion topped forecasts by $70 million.
The Fed will release a statement following the conclusion of its two-day meeting on Wednesday afternoon. While the central bank isn't expected to raise interest rates at the October meeting, Wall Street will be listening for clues about the possibility of a rate hike when the Fed meets again in December.
"The trajectory of recent U.S. data further complicates the Fed's liftoff timing, as does the Committee's desire to simply get off the zero-bound," wrote CRT Capital's Ian Lyngen in a note. "It promises to be an interesting, if prolonged, process."