The past few years have been undeniably profitable for Nvidia ( NVDA 4.43%) investors. The stock price has surged more than sevenfold over the past two years, and today, it topped the charts as the world's most valuable company in terms of market cap. The stock was up as much as 4.7% Wednesday morning. At 12:32 p.m. ET, the stock was still up 4.1%.

Nvidia is once again the most valuable U.S. company, outranking Apple for the first time since late November. A rise in the chip maker's stock meant it ended Tuesday with a market capitalization of $3.