BUCHAREST (Romania), February 23 (SeeNews) – Global rating agency Fitch said on Tuesday it has downgraded the Long-term and Short-term Issuer Default Ratings (IDR) of Greece's four largest banks, National Bank of Greece (NBG), Alpha Bank (Alpha), Efg Eurobank Ergasias (Eurobank) and Piraeus Bank (Piraeus), to 'BBB' from 'BBB+' and 'F3' from 'F2' respectively, with a negative outlook.