NEW YORK (Standard&Poor's) Aug. 22, 2005--Standard&Poor's Ratings Services said today that it lowered its ratings on Nexstar Broadcasting Group Inc., including lowering its long-term corporate credit rating to 'B' from 'B+', because of the company's weaker-than-expected operating performance and high leverage. The outlook is stable. Total debt, including debt obligations of Mission Broadcasting that are guaranteed by Irving, Texas-based Nexstar, totaled approximately $648 million at June 30, 2005. "The downgrade recognizes that softer-than-expected advertising demand gives us greater concern that the company will not achieve the near-term leverage reduction that we had used in our previous rating assumptions," said Standard&Poor's credit analyst Alyse Michaelson Kelly. The shortfall in ad demand recently prompted Nexstar to