When a stock is up more than 160% in a year, it can be easy to think you missed the boat. However, that's not always the case, and when a high-flying stock like pharma darling Regeneron (REGN 2.06%) pulls back, it can serve as a buying opportunity. In the following video, Brenton Flynn explains why investors shouldn't be shocked by the news that has this stock down about 5% today.