Apple, Microsoft, Nvidia, Amazon, Alphabet, Meta, and Tesla, collectively known as the "Magnificent Seven," have a combined market value of more than $20 trillion. That's in the same range as China's annual economic output, the second-largest economy in the world.

The dollar amounts may be comparable, but they tell two very different stories.

A country's gross domestic product (GDP) is the value of all the goods and services it produces in a year. A company's market capitalization is the total value of all its outstanding shares, based on the current stock price.

One measures a year's worth of economic activity. The other reflects what investors collectively believe a company is worth at that moment.

The comparison isn't perfect, but it highlights the extraordinary scale of today's largest companies. 

Together, just seven publicly traded businesses now command valuations comparable to the annual economic output of one of the world's largest economies.