MEXICO CITY (Standard&Poor's) Dec. 1, 2005--Standard&Poor's Ratings Services placed its 'BB-' long-term foreign and local currency corporate credit ratings on Grupo Posadas S.A. de C.V. (Posadas) on CreditWatch with negative implications. At the same time, Standard&Poor's placed its 'mxA-' national scale rating on Posadas on CreditWatch negative. The 'BB-' senior unsecured debt rating on Posadas was also placed on CreditWatch Negative. "The CreditWatch listing follows the announcement that Posadas' offer of $165.5 million for 100% of the assets of Grupo Mexicana de Aviación S.A. de C.V. was accepted," said Standard&Poor's credit analyst Fabiola Ortiz. Even though the effect of the acquisition on Posadas' business profile could be beneficial in the long term,