* Amazon.com: Amazon is currently valued at around $850 billion, and has been growing at a rapid pace. It is expected to reach $1 trillion in market capitalization within the next few years.

* Alphabet (Google): Alphabet, the parent company of Google, has a market capitalization of around $700 billion. The company is expected to reach $1 trillion in market capitalization within the next few years.

* Microsoft: Microsoft is currently valued at around $1.4 trillion making it the second bigest company in the world.

* Saudi Aramco: Saudi Aramco is the world largest oil company and it has a market capitalization of around $2 trillion, making it the biggest company in the world.