AXA IM, which has 582 billion euros (465.83 billion pounds) in assets under management, said in a note dated Sept. 11 that it had also upgraded euro zone bonds to "neutral".

"Abating geopolitical risks combined with massive ECB liquidity injections are a strong tailwind for equities," AXA IM Chief Strategist Franz Wenzel wrote. "Furthermore, the economic recovery is on track despite a growing difference between the U.S. and the euro area."

In early August, AXA IM cut its short-term recommendation on global equities to "neutral", arguing that investors should switch to cash given the slow pace of economic recovery in Europe and rising geopolitical risk.

(Reporting by Blaise Robinson; Editing by James Regan)