Newly inflamed trade war fears and disappointing earnings sent US stocks lower on Thursday, running counter to gains made in European equities.
Benchmark oil contract Brent North Sea briefly hit its highest level since late 2014, breaching $80 per barrel and sparking fears it could soon hit $100, before calming later in the day.
Higher oil prices, in turn, pushed the shares of energy firms in European stock markets higher, helping London's FTSE to set a new all-time high, and the Paris CAC to establish a fresh 2018 peak.
Wall Street had an indecisive trading day, flipping in and out of negative territory on a swirling mix of worries to finish lower: the Dow and Nasdaq both lost 0.2 percent.
The day's final southward turn came after US President Donald Trump lashed out at European and Chinese trading partners and cast doubt on the chances of reaching a deal with Beijing, even as visiting Chinese officials were in Washington to conduct talks.
"I tend to doubt it," Trump said about the chances for successful talks. "China has become very spoiled... because they always got 100 percent of whatever they wanted from the United States."
In a sign that investors could be looking for safe harbor amid geopolitical turmoil, the Russell 2000 -- an index of small-cap stocks more insulated from global trade -- hit an all-time high.
Karl Haeling of LBBW bank told AFP Thursday's dip in stocks was more a question of "general uncertainty about trade and interest rates" rather than any single concern. And the Russell 2000's out-performance of the wider market suggested this, he said.
- Oil, Iran and inflation -
"Given the uncertainty over trade, Iranian sanctions and various other geopolitical hot spots, people are making a bet that US growth will outperform the rest of the world and that these companies will be less affected," he said.
But Dow heavyweights Walmart and Cisco weighed on the index, falling after posting strong earnings that failed to impress Wall Street analysts.
Meanwhile, Patrick Pouyanne, the CEO of French oil giant Total, said Thursday he "wouldn't be surprised to see $100 per barrel" in the coming months.
Global oil supplies could be hit by President Donald Trump's decision this month to pull the United States out of the 2015 Iran nuclear deal, and also by falling production in crisis-hit Venezuela, the International Energy Agency said on Wednesday.
Prior to Thursday's oil-price rally, crude futures had already risen thanks to steady demand growth and a landmark production cut deal. Oil's rise could meanwhile further push up inflation, impacting growth by quickening the pace of expected increases in interest rates.
With markets expecting inflation to pick up pace, including for other reasons such as improved wage growth, 10-year US bond yields have hit seven-year highs, adding to expectations of a series of US rate hikes this year.
On currency markets, the dollar benefited from bets on higher US rates, keeping it around multi-month highs against its major peers. A string of disappointing data on the European Union is also bearing down on its single currency.
In Milan, shares in Banca Monte dei Paschi di Siena, the world's oldest bank, fell nine percent after the anti-establishment Five Star Movement and the far-right League said that after forming a government they wanted to "redefine its mission."