OREANDA-NEWS. Fitch Ratings (Thailand) has today assigned Japan-based Mizuho Bank, Ltd.'s (MHBK, A-/Stable) THB3bn senior unsecured notes due September 2018 a final National rating of 'AAA(tha)'.

The rating action follows the completion of the notes issue, as well as the receipt of final documents conforming to information previously received. The final rating is the same as the expected rating assigned on 10 September 2015.

KEY RATING DRIVERS

The National rating on the notes is based on MHBK's Long-Term Foreign-Currency Issuer Default Rating (IDR) of 'A-', which is at the same level with Thailand's Long-Term Local-Currency IDR of 'A-' and hence correlated to 'AAA(tha)', the highest rating on Thailand's National rating scale.

MHBK's Long-Term Foreign-Currency IDR is based on sovereign support, and is at the bank's Support Rating Floor (SRF) of 'A-' as the bank is considered a systemically important financial institution in Japan.

MHBK is one of the subsidiaries of Mizuho Financial Group, Inc. (A-/Stable). The group is the second-largest bank in Japan by total assets.

RATING SENSITIVITIES
The 'AAA(tha)' rating on MHBK's senior notes is the highest on the National scale and, hence, no rating upside is possible.

A downgrade could be triggered if MHBK's Long-Term Foreign-Currency IDR is lower than Thailand's Long-Term Local-Currency IDR, either through a downgrade of MHBK's rating or an upgrade of Thailand's rating. However, this is unlikely to occur in the near-term as reflected by their Stable Outlooks.

MHBK's other ratings are not affected and are as follows:
- Long-Term Foreign and Local Currency IDRs at 'A-'; Outlook Stable
- Short-Term Foreign and Local Currency IDRs at 'F1'
- Viability Rating at 'bbb+'
- Support Rating at '1'
- Support Rating Floor at 'A-'
- Senior unsecured debt at 'A-'