Fixed U.S. mortgage rates rose for a third straight week, signaling the Federal Reserve Board's plan to lower borrowing cost is stalling.

The average 30-year rate jumped 30 basis points from the previous week, to 5.59%, for the week that ended Thursday, Freddie Mac said. The 15-year rate averaged 5.06%, Freddie said Thursday.

The Fed said March 18 that it would purchase as much as $1.25 trillion in securities from Fannie Mae and Freddie Mac to help drive borrowing costs lower. The program helped push rates to a record-low 4.78% twice in April.

Now rates are climbing along with Treasury yields on investor concern that a greater supply of government debt being sold to fund federal spending will fuel inflation. Yields on Fannie and Freddie mortgage securities rose Wednesday to a level not seen since the Fed announced its plan.

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