Analyst upgrades are significant indicators for investors as they reflect a change in the outlook of a company's performance. UBS's upgrade from Neutral to Buy suggests that they see improved fundamentals or potential in First Horizon, which can lead to increased investor interest and a short-term positive impact on the stock price. The relevance is high as the news is directly about FHN, and the importance is also high given that analyst ratings can influence market perception and investment decisions. The confidence level is set at 90, acknowledging the general impact of such upgrades while allowing for market unpredictability.