ToplineShares of MicroStrategy rallied Monday after the corporate bitcoin holder earned a spot in a key stock index, an apparent institutional vote of confidence in the company whose stock has been red hot amid the cryptocurrency boom.MicroStrategy chairman Michael Saylor speaks at a 2021 conference.Getty Images Key FactsMicroStrategy stock gained 4% at market open, enjoying a bump from the Nasdaq announcing after Friday’s close that the Virginia-based company would join its Nasdaq 100 stock index next Mond ...