For the first time since 2009, yields on bonds sold by French and German companies were higher last month than for Spanish and Italian borrowers, Bank of America Merrill Lynch data show.
Peripheral firms were even able to borrow cheaper than US companies.
Telefonica SA sold eight-year notes yielding 2.242 percent in May compared with a yield of 2.445 percent on similarly rated debt of the same maturity issued by US phone carrier Verizon Communications Inc and 2.465 percent from cable television channel operator Discovery Communications Inc in February.
“Peripheral companies shouldn’t be trading below their core peers,” said Thomas Kristiansson, head of credit fixed-income at SEB.
They “are still vulnerable,” he said.
Borrowers are making the most of the low rates, selling a record 27 billion euros of securities this year, up 9 percent from the same period in 2013, data compiled by Bloomberg show.
Greek issuers such as Public Power Corp SA, the nation’s largest electricity company, are on pace to raise the most since 2008 with 1.5 billion euros of bond sales.