With markets locked down ahead of the highly-anticipated address at the Jackson Hole symposium at 1400 GMT, a 30% surge for Peppa Pig-owner Entertainment One was among the few major share moves.

That reflected a premium over the price agreed with U.S. toy giant Hasbro in a deal announced overnight, and some analysts suggested it could point to some kind of counter offer, possibly from UK broadcaster ITV, whose shares rose 4%.

Shares in Kloeckner & Co also jumped 11% after a newspaper said Thyssenkrupp was in talks to buy the metals distributor to strengthen its materials trading business.

That helped the pan-European STOXX 600 index rise 0.4% by 0810 GMT, still more than 2% down on the month but on course for its first weekly gain since July.

"A lot of optimism has been building up ahead of Powell's speech and it is possible that markets are positioned to be disappointed," said Craig Erlam, senior market analyst at OANDA in London.

Markets have seen wild swings in August as fears that the slowing economic effects of the U.S.-China trade war could tip major economies into recession were countered by expectations central banks and governments will step in.

Minutes from the Fed's July meeting have cooled money market expectations of a bigger half-percentage point cut in rates next month but also potentially left Powell the room to be more dovish than the panel as a whole sounded.

The FTSE 100 rose 0.6% and the euro-zone benchmark  gained 0.5%.