Money managers with more than $800 billion are betting European policy makers can only offer Spain a temporary respite from record borrowing costs.

Yields on Spain’s two-, five-, 10- and 30-year government securities climbed to euro-era highs this week amid speculation the nation will need a bailout to backstop its regions and banks. While the Organization for Economic Cooperation and Development called for the European Central Bank to buy Spanish debt, investors including AllianceBernstein Ltd. and M&G Group Plc said policy makers are hamstrung in how to rescue an economy twice the combined size of Greece, Ireland and Portugal.

“This crisis is unprecedented so the responses need to be unprecedented,” said Arif Husain, the London-based director of European fixed-income at AllianceBernstein, which oversees $407 billion. “Anything the ECB can do would prove temporary. The whole problem is that anything that’s happening at the moment is unconvincing, and markets hate uncertainty.”

Spain’s 10-year yield reached as much as 7.751 percent yesterday, and was at 7.05 percent as of 12:20 p.m. London time. Five- and 30-year yields also reached the most since the common currency was introduced in 1999 this week, while the cost of insuring against a default climbed to its highest ever.