Intel. Only Microsoft, which was the largest publicly traded company in 1999, remains in the top 10 today. It's currently second, with a $1.9 trillion market cap. Innovation, earnings, acquisitions, and a host of other decisions are what lead to this constant flux among the world's biggest businesses. Image source: Getty Images. Today, Apple (NASDAQ:AAPL) sits at the head of the table with a market cap north of $2.2 trillion. This hearty valuation comes after Apple introduced 5G-capable iPhones late last year. The tech kingpin has sold an astounding $113.5 billion of the devices in just the first six months of its current fiscal year. That's up from $84.9 billion over the same time frame one year ago.