The rating outlook is stable.
In a statement, Moody's said the downgrade reflects the view of a more aggressive risk appetite evidenced by the company's debt-funded acquisition of a 28.61 per cent stake in F&N and execution risks associated with international expansion through its collaboration with F&N.
Moody's put the rating under review in July 2012, after ThaiBev announced the plan to acquire a minority stake in F&N, a pan-Asian consumer group engaged in food and beverages, properties, and publishing and printing.