"The tight trading ranges seen so far this month reflect the cautious mood in the market ahead of the inflation numbers," said Fiona Cincotta of City Index.
Asian markets were broadly down for a second day. Tokyo extended Tuesday's more than three percent plunge, while Taipei's tech-rich bourse tumbled more than two percent.
"A lot of investors are worried about the stock market highs, but that doesn't mean it can't get higher, and the economic conditions are certainly set up for a positive equity environment," she told Bloomberg TV.
European shares dipped to near two-week lows, while oil prices bounced back from steep losses on Tuesday after a ship ran aground in the Suez Canal, though traffic was expected to resume soon.
The mood is fairly fragile as all the optimism that characterised the push higher over the past two or three weeks in shares is starting to bleed away on talk of a European third wave and extensions of pandemic lockdowns in Germany and France.
"The number of new COVID-19 cases is rising rapidly, and an extension of the lockdown inevitable for many European countries. No one will be surprised by such a decision," said Milan Cutkovic, market analyst at Axi.
MSCI's gauge of stocks across the globe shed 0.04%, with slight gains in Europe but a 2.1% decline in Japan's Nikkei index.
Bitcoin rose 1.8% to $23,223, extending its weekly gains to 21.3%, with a break of the $20,000 mark on Wednesday triggering a fresh wave of buying binge.