European stocks closed firmly higher on Tuesday, getting a lift after Greece signed a deal to release the next tranche of bailout aid and after data showed eurozone manufacturing output on the rise.

U.S. stocks ended with a slight upward bias on Tuesday, though investors mostly held off on making big bets with the Federal Reserve engaged in a two-day policy meeting, which ends on Wednesday. Caution was high as the Fed's meeting got underway; while central bankers are expected to keep rates on hold at this meeting, analysts are looking for any comments on the recent slowdown in U.S. economic activity.

Stock prices increased early Wednesday in Asia, where some major markets are closed for holidays as traders await the latest statement from the U.S. Federal Reserve. But Australian stocks lagged behind for a second session as bank stocks continue to weigh on activity there.