Moody's Investors Service, a rating arm of Moody's Corp. ( MCO ), downgraded the rating outlook of First Horizon National Corporation ( FHN ) and its subsidiaries. Moody's downgraded the senior unsecured debt rating of First Horizon to Baa3 from Baa2. Additionally, the baseline credit assessment ( BCA ) of First Tennessee Bank – the primary banking subsidiary – was lowered to baa2 from baa1. However, the standalone bank financial strength rating (:BFSR) of First Tennessee Bank was affirmed at C-. Therefore, the long-term deposit rating of First Tennessee Bank was downgraded to Baa2 from Baa1, whereas the short-term deposit rating was affirmed at Prime-2. Why the Downgrade? The rating agency is concerned with First Horizon's obstacles to reach heightened profitability, primarily from the company's legacy mortgage banking business.