Shares of Walgreens Boots Alliance (NASDAQ: WBA) climbed 12.7% in July, according to data from S&P Global Market Intelligence, rebounding on the heels of its plunge in late June after Amazon.com's threatening purchase of online pharmacy PillPack.Shares of Walgreens fell 10% on June 28 alone as the market reacted to Amazon's purchase, which many industry watchers viewed as putting the online retail behemoth in direct competition with the broader pharmacy sector.