Fitch Ratings has today assigned Thailand-based KT ZMICO Securities Company Limited (KTZ) a National Long-Term Rating of 'A+(tha)' and a National Short-Term Rating of 'F1+(tha)'. The Outlook is Stable. The agency has also rated KT ZMICO's outstanding senior unsecured debt at 'A+(tha)'. KEY RATING DRIVERS NATIONAL RATINGS AND SENIOR DEBT KTZ's National Long-Term Rating reflects Fitch's assessment of extraordinary support from its majority shareholder, Krung Thai Bank Public Company Limited (KTB;