Like I said - everything sounds impossible until it is achieved.
Apple on the 17th December 2017 hit a record of $909.8B market cap.
PetroChina on 5th November 2007 hit a record of $1 trillion market cap.
According to Bank for International Settlements there is $5 trillion around the world.
According to the CIA, the total amount is $80 trillion if you include "broad money."