The trading lower of UBS shares is directly linked to the mixed Q4 financial results reported by the company. This indicates that the financial performance was not entirely up to market expectations, leading to a negative short-term impact on the stock price. The high relevance score is due to the direct mention of UBS's financial results being the cause of the stock's movement. The importance is high as earnings reports are critical for investors' decision-making. The confidence level is high due to the clear cause-and-effect relationship between earnings reports and stock price movements.