The premium investors demand to hold French government bonds jumped to its highest since the euro zone debt crisis in 2012 on Friday, highlighting market nerves about parliamentary elections this weekend.
Polls put Marine Le Pen's far-right National Rally first, mostly short of an absolute majority. But it has been extending its lead and one poll showed it could potentially cross the threshold for an absolute majority. A left-wing alliance is seen coming second.
French government bond prices fell on Friday ahead of the first round of voting on Sunday, with the 10-year yield rising as much as 6 bps to 3.328%, its highest since bonds tumbled on June 11 in the wake of the election call. Yields move inversely to price.
The moves pushed up the so-called spread between the French and German borrowing costs - a measure of the extra return investors demand to buy France's debt - to as high 85.2 bps, the widest since 2012.
"The ongoing uncertainty stemming from the French elections and potential fiscal implications are major market concerns," said Emmanouil Karimalis, macro rates strategist at UBS. "We are just two days away from the first round of elections, and I think it is natural for the market to be nervous."
The spread retreated in late trade as the French yield eased to 3.29%, and German bond yields rose, putting the spread at 81 bps.
The 10-year German bond yield , the benchmark for the euro area, touched its highest since June 13 and was last up 3 bps to 2.49%.
Karimalis said the first round of voting failed to provide clarity in 2022, so markets were likely to remain jittery going into the second round on July 7.
BOND SPREADS REMAIN FAR BELOW 2012 PEAKS
Government bond spreads blew out in 2012 as investors panicked about a potential break-up of the euro zone during a sovereign debt crisis. They remain far below peaks seen 12 years ago.
The gap between Italy and Germany's 10-year bond yields expanded to its widest since mid-February at 160 bps , in a sign of nerves spreading to other highly indebted countries.
Some strategists believe markets are getting ahead of themselves.
"These French election jitters, quite frankly it's overdone," said Piet Haines Christiansen, chief strategist for fixed income research at Dankse Bank.
He said France's structural problems were unlikely to be made better or worse by the election outcome and expected the yield spread to tighten somewhat.
Beyond France, economic data was also on markets' agenda on Friday.
The U.S. Federal Reserve's preferred measure of inflation - the personal consumption expenditures index - came in largely in line with expectations at 2.6% year-on-year for both the headline and core figure, initially prompting a drop in bond yields.
Earlier, markets barely budged in response to largely in line June French, Spanish and Italian inflation data.
