From hero to zero in just 10 days: May's sell-off has seen year-to-date gains for holders of US Treasuries, German bunds and UK gilts wiped out and turned to losses. Some are asking if this is a definitive turning point for the bond market after its 30-year bull run. It isn't clear yet that global yields have hit bottom—but it is clear that bonds are becoming hypersensitive to the smallest twists and turns in the economy.

The turn in mood has been sharp. On May 2, after the European Central Bank cut rates and hinted that it might yet push the rate on its deposit facility into negative territory, 10-year German yields hit a record low around 1.15%; US yields were at a low for the year of 1.63%. But since then, a better-than-expected US jobs report, some encouraging German industrial data and a brewing debate about how and when the US Federal Reserve might wind down its bond-purchase program have pushed yields sharply higher, to 1.36% in Germany and 1.92% in the US Gilt yields have broadly tracked Treasuries.