The U.S. central bank was widely expected to do another quarter-point rate hike - possibly the last in its current cycle of increases.
European stocks slipped a by around half a percent in early trades as caution prevailed.
Markets also had a deluge of earnings to digest.
Among big lenders, Deutsche Bank dropped 1% after it said profits fell by more than a quarter.
It was hit by a slump in investment banking.
Spanish giant Santander initially gained nearly one percent after its profits jumped, but later fell back.
Luxury titan LVMH dropped 4% even though it narrowly beat earnings forecasts late the day before.
Investors were concerned by its failure to give any forecast for sales in China.
Rolls-Royce shot up more than 20% after it raised its profit outlook by almost a half.
After a tough few years, the jet-engine maker is getting a boost as travel rebounds and military spending soars.
Shares in mining giant Rio Tinto dropped around 2% after it said softer iron ore prices had driven profits to a three-year low.
Other big names to report earnings on Wednesday included GSK, Danone and car group Stellantis.
