Few stocks have had as good a run as Palo Alto Networks ( PANW -1.53% ) has had over the past five years. The cybersecurity company's stock has risen by nearly 360%, which prompted management to conduct a 2-for-1 stock split on Dec. 16. While a stock split is mostly cosmetic, and doesn't change anything about the underlying business or its investment thesis, it does make it easier for investors who don't have the ability to buy fractional shares to add a stock to their portfolios.