The S&P 500 is rallying toward a 25% increase this year, and many growth stocks have greatly contributed to the gain. The one that stands out, though, is Nvidia (NVDA -3.26%). It's become a stock market star thanks to its leadership in the artificial intelligence (AI) chip market, holding about 80% share. AI customers have been flocking to Nvidia for its AI chips and related products and services, and this has helped earnings soar in the triple digits quarter after quarter.And speaking of quarterly performa ...