MONTERREY, Mexico--(BUSINESS WIRE)--Fitch Ratings has revised the Rating Outlook on Banco Nacional de Mexico, S.A.'s (Banamex) long-term local currency (LC) Issuer Default Rating (IDR) to Positive from Stable. Simultaneously, Fitch has affirmed Banamex's Viability Rating (VR) at 'a' and its long-term foreign and local currency IDRs at 'A'. Also, Fitch has affirmed the national scale ratings of Banamex and Acciones y Valores Banamex, S.A. de C.V., Casa de Bolsa (Accival) at 'AAA(mex)' and 'F1+(m