Equity markets around the world retreated on Friday as mounting unease over ineffective central bank growth policies and Britain's looming referendum on EU membership sent investors flocking to bonds.
A 0.9 percent fall in the S&P 500 capped a rout that crossed from Asia through Europe and was matched by a fall in oil prices, while gold pushed higher for the fourth straight session.
Frankfurt and Paris both lost more than two percent, and London fell 1.9 percent.
Milan's main index slumped 3.6 percent and Madrid 3.1 percent.
"Global stocks slumped as investors sought the safety of government bonds," said analyst Jasper Lawler at CMC Markets. 
"People are rushing to safety... prompted by fears of the British referendum," said Peter Cardillo, chief market economist at First Standard Financial.
Signs of general concern were clearest in bond markets. The yield on the Bund, Germany's 10-year government bond, edged closer to negative territory, hitting 0.02 percent. The US 10-year Treasury bond fell to its lowest level since February at 1.64 percent.
The equities losses came after a healthy run of gains helped in part by a recovering oil market. But markets were spooked Thursday by European Central Bank chief Mario Draghi calling for governments to step up spending to help kickstart eurozone growth.
His comments were taken as a sign that the ECB's arsenal for boosting growth is running low following the launch this week of corporate bond purchases.
Underpinning that were comments by billionaire investors George Soros and Carl Icahn that risks had risen worldwide amid slow growth.
- Brexit fears rising -
In addition, markets showed increasing restlessness over the Brexit vote on June 23, which if in favor of Britain breaking from the European Union could unleash a wave of turmoil across world markets.
The pound fell by two cents against the dollar to $1.4250, and also lost ground against the euro.
German Finance Minister Wolfgang Schaeuble on Friday issued a stark warning that Britain would face costly barriers to the EU trade zone if it left the bloc.
"The economic impact of the EU vote is riding high in investors' minds as they try to assess how it will affect the UK, European and global market outlook over the coming months," said Dave Jeal, head of investment products at stockbroker Interactive Investor. 
Those issues "make this a time for more cautious investors to take a back seat," he added.
Market focus was starting to turn toward next week's monetary policy meetings of the US and Japanese central banks.
Neither is expected to make any policy shift; the poor US May jobs report took any thought of a US interest rate hike off the table at the Fed, analysts said. Fed funds futures now show a market expecting a rate hike only in December.
- Key figures at 2100 GMT -New York - DOW: DOWN 0.7 percent at 17,865.34 (close)
New York - S&P 500: DOWN 0.9 percent at 2,096.07 (close)
New York - Nasdaq: DOWN 1.3 percent at 4,894.55 (close)
London - FTSE 100: DOWN 1.9 percent at 6,115.76 (close)
Frankfurt - DAX 30: DOWN 2.5 percent at 9,834.62 (close)
Paris - CAC 40: DOWN 2.2 percent at 4,306.72 (close)
EURO STOXX 50: DOWN 2.6 percent at 2,911.11 (close)
Tokyo - Nikkei 225: DOWN 0.4 percent at 16,601.35 (close)
Hong Kong - Hang Seng: DOWN 1.2 percent at 21,042.64 (close)
Shanghai - Composite: Closed for a public holiday
Euro/dollar: DOWN at $1.1251 from $1.1315 late Thursday
Dollar/yen: DOWN at 106.93 yen from 107.10 yen
Euro/pound: UP at 78.95 pence from 78.29 pence
Pound/dollar: DOWN at $1.4250 from $1.4453
(AFP)