Analyst ratings, especially from prominent financial institutions like Morgan Stanley, can significantly influence investor perception and stock prices. An Overweight rating suggests that the analyst believes the company's stock price will outperform the average return of the stocks in the analyst's coverage universe. The announcement of an $85 price target, which is presumably higher than the current trading price, indicates a bullish outlook on AstraZeneca's performance, potentially leading to increased investor interest and a rise in stock price in the short term.