MOSCOW: The Russian rouble firmed on Monday, helped by ratings agency Moody's upgrading the country's sovereign rating to investment grade. Late on Friday, Moody's Investor Service raised Russia's rating to Baa3 from Ba1, saying the policies enacted in recent years will strengthen the country's already robust public finances and will help it withstand possible US sanctions against Moscow. "The upgrade is likely to support the rouble and OFZs, which could be easily limited by fear of upcoming US sanctions," said Vladimir Miklashevsky, senior economist and trading desk strategist at Danske Bank in Helsinki.