ArcelorMittal downgraded to Ba1 by Moody's, outlook negative Moody's Investors Service downgraded ArcelorMittal's senior unsecured note ratings to Ba1 from Baa3. The rating action includes the senior unsecured notes and Euro MTNs of ArcelorMittal and the senior unsecured notes of ArcelorMittal Finance and ArcelorMittal USA. The rating for the parent's subordinated perpetual capital security was lowered to Ba3 from Ba2 and its commercial paper rating was lowered to NP from P-3. A corporate familly and probability of default rating of Ba1 was assigned to ArcelorMittal. The rating outlook remains negative for all three debt issuers.The downgrade reflects the deterioration in global steel markets over the last six months, as evidenced by ArcelorMittal's third quarter 2012 performance, its worst quarter since 2Q09.