The reiteration of an Outperform rating by a reputable analyst like David Nierengarten from Wedbush is a positive signal for Chimerix. It indicates that the analyst believes the company's stock will outperform the market or its sector in the short term. The maintained price target of $6 also shows the analyst's confidence in the company's potential to reach this price. This could lead to increased investor confidence and potentially a rise in the stock's price in the short term.