Every once in a while, a major brand name and its stock’s existence are challenged. Often, the price action and the threatening state of the company are justified, and the business does end up going under. Other times, this is not the case, and investors can catch a life-changing rally in their portfolios. Today, one stock offers investors such an opportunity. It can be found in shares of healthcare sector retailer Walgreens Boots Alliance Inc. (NASDAQ: WBA) now that they trade at only 33% of its 52-week high, which is where investors can begin to build a potential bull case carrying double-di…