Radian Group Inc. (RDN) said Thursday morning that it had entered into a waiver agreement with its lenders under its core credit facility, giving it a temporary suspension of a key ratings covenant that required the mortgage insurer to maintain an unspecified minimum rating with major ratings companies. The suspension will be in effect until the end of April as the company and its creditors look to hammer out a formal amendment to credit terms, it said in a press statement. The waiver, however, effectively freezes any further borrowing for the mortgage insurance giant. Along with three other major mortgage insurers, Radian's key insurer financial strength rating was cut below the critical AA- threshold earlier this week by Standard & Poor's, who said it now expected housing price declines to be steeper than originally projected. Larger price declines usually translate into both higher claims and greater losses on claims for private mortgage insurers.