Advanced Micro Devices (AMD.O) was up 1 percent after a report that Tesla (TSLA.O) is working with the chipmaker to develop its own artificial intelligence chip for self-driving cars. The average is on a six-day streak of new highs.
Woodside Petroleum and Santos surged around 2% after oil prices settled 2% higher overnight.
While the Nasdaq is down 19.90 points or 0.3% at 6,441.43, the Dow is up 16.92 points or 0.1% at 22,387.72 and the S&P 500 is up 0.23 points or less than a tenth of a % at 2,506.88.
It was widely expected that the USA central bank won't raise interest rates following the meeting, but investors believe the Fed will announce the unwinding of its $4.5-trillion balance sheet.
Australian shares fell sharply to hit three-week lows after the Fed indicated that a third rate hike might be on the table in December.
The financial sector.SPSY was among the two gainers as banks tend to perform better in a higher rate environment. Several packaged food companies also declined.
Energy stocks were rising along with the price of crude oil early Wednesday.
"People are still, as they usually are the day before a Fed announcement, kind of in a wait-and-see mode", said Lindsey Bell, investment strategist at CFRA Research.
Shares of Calgon Carbon soared 59.1 percent in premarket trading after Japanese chemical manufacturer Kuraray agreed to buy the carbon materials firm for $1.107 billion. Economists had expected the index to edge up by 0.2 percent. Many expect the central bank to announce Wednesday that it will keep rates unchanged and that it will start unwinding its $4.5 trillion balance sheet.
Economic data showed the number of Americans filing for unemployment benefits fell unexpectedly to 259,000, but the data continued to be influenced by Hurricanes Harvey and Irma, muddying the labor market picture in the near term.
After the statement traders were betting on a roughly 67 per cent chance of a December hike, compared with 51 per cent minutes before, according to the CME Group's FedWatch tool.
Meanwhile the Organization for Economic Cooperation & Development said in an interim update that global growth momentum has improved and is more broad-based now, but a self-sustained recovery is far from secured as inflation remains subdued and there exists an unmet need for structural reforms. The Nasdaq slipped 5 points to 6,456.
Seven of the 11 major S&P sectors were higher, led by a 2.14 percent gain in the telecom services sector.
Mostly, though, investors were focused on what the Fed will say today. The big four banks slid between 0.3% and 0.9%.
Shares of Apple fell 1.7 per cent after it admitted its latest smartwatch has connectivity problems.
Advancing issues outnumbered decliners on the NYSE by 1,395 to 1,365.
Roughly 6.7 billion shares changed hands on US exchanges compared with the 6 billion average for the last 20 sessions.