* Dudley sees Fed rate hikes as U.S. inflation weakness fades
* Apple down after muted launch for iPhone 8
* General Motors up after brokerage upgrade
* Indexes down: Dow 0.04 pct, S&P 0.12 pct, Nasdaq 0.56 pct (Updates to open)
By Sruthi Shankar
Sept 25 (Reuters) - A selloff in technology stocks, led by Facebook and Apple, drove down major Wall Street indexes on Monday.
Apple fell more than 1 percent, extending its losses from last week due to a lukewarm response to its iPhone 8 globally.
Facebook's 3.2 percent was the biggest drag on the S&P 500 and the Nasdaq.
Heightened expectations of another interest rate hike this year following comments from a Federal Reserve official also added to the downbeat sentiment.
The central bank is on track to gradually raise interest rates as factors depressing inflation are fading and the U.S. economy's fundamentals are sound, New York Federal Reserve President William Dudley said.
Investors are also awaiting a speech by Fed Chief Janet Yellen later in the week for more guidance on the monetary policy.
"Investors would like to get more clarity as far as what the Fed is going to do as they move forward with the unwinding of the balance sheet and how they are going to move forward next year," said Robert Pavlik, chief market strategist at Boston Private Wealth in New York.
The U.S. central bank left interest rates unchanged in its September policy meeting, as expected, but signaled it still expects one more increase by the end of the year, despite a recent bout of low inflation..
At 9:39 a.m. ET (1339 GMT), the Dow Jones Industrial Average was down 8.21 points, or 0.04 percent, at 22,341.38, the S&P 500 was down 3.1 points, or 0.12 percent, at 2,499.12 and the Nasdaq Composite was down 36.20 points, or 0.56 percent, at 6,390.72.
Five of the 11 major S&P sectors were lower.
General Motors rose 2.46 percent after Deutsche Bank upgraded the automaker's stock to "buy", pointing to its autonomous vehicles, which could be ready for deployment within quarters.
Allergan was up more than 2.6 percent after the drugmaker authorized a $2 billion buyback of its shares and said its chief financial officer would retire.
Chicago Chief Charles Evans and his Minneapolis counterpart, Neel Kashkari are scheduled to speak later in the day.
Advancing issues outnumbered decliners on the NYSE by 1,391 to 1,085. On the Nasdaq, 1,279 issues fell and 1,061 advanced. (Reporting by Sruthi Shankar in Bengaluru; Editing by Anil D'Silva)