-- Silicones producer Momentive announced an exchange offer for certain of its existing senior notes. -- We are lowering our corporate credit rating on Momentive to 'CC' from 'CCC'. -- The ratings are remaining on CreditWatch with negative implications to reflect our view that the completion of the exchange is likely. -- We will lower the corporate credit rating to 'SD' (selective default) upon completion of the exchange offer. NEW YORK (Standard&Poor's) May 13, 2009--Standard&Poor's Ratings Services said today that it lowered its ratings on Momentive Performance Materials Inc. and its subsidiaries by two notches, including its corporate credit rating to 'CC' from 'CCC'. The ratings remain on CreditWatch with negative implications, where they were originally