The reduction in price target from $15 to $5 by a reputable analyst firm like HC Wainwright & Co. could negatively impact investor sentiment in the short term, potentially leading to a decrease in the stock price of Oncolytics Biotech. The maintenance of a Buy rating suggests underlying confidence in the company's fundamentals, but the drastic cut in the price target is likely to be the dominant factor affecting the stock's performance in the immediate future.