The maintenance of a Sell rating by UBS suggests a negative outlook on Rivian Automotive's stock, indicating that the analyst believes the stock may underperform. However, the increase in the price target from $8 to $9 suggests a slightly less bearish view than before, possibly due to some positive developments or adjustments in valuation models. Despite this, the overall recommendation remains negative, which could lead to a short-term negative impact on the stock price.