MBIA, Ambac credit insurance costs up after downgrade

NEW YORK, June 20 (Reuters) - The cost of insuring the debt of the insurance arms of Ambac Financial Group (ABK.N) and MBIA Inc. (MBI.N) rose on Friday, a day after Moody's Investors Service stripped them of their triple-A ratings.

Five-year protection costs on MBIA Insurance rose to about 38.5 percent on an upfront basis, plus 500 basis points in annual premiums. That was up from 31.5 percent upfront plus 500 basis points on Thursday, according to data from Phoenix Partners group. That means it costs $3.85 million upfront plus $500,000 annually to protect $10 million of debt for five years.

Ambac Assurance's credit protection costs rose to 38 percent upfront plus 500 basis points a year, up from 32 percent upfront plus 500 basis points on Thursday, according to Phoenix Partners Group data. (Reporting by Dena Aubin; Editing by Dan Grebler) (dena.aubin@thomsonreuters.com; +1-646-223-6325; Reuters Messaging: dena.aubin.reuters.com@reuters.net))