https://arstechnica.com/tech-policy/2021/02/bitcoins-value-just-passed-1-trillion/

Bitcoin's price soared past $56,000 on Friday, pushing the combined value of all bitcoins past the $1 trillion mark—at least in theory. That's more than the market capitalization of Facebook, though Apple, Alphabet, Amazon, and Microsoft are worth more. Bitcoin's value has almost doubled from $29,000 since the start of the year.

I say "in theory" because not all bitcoins are actually available for use. Each bitcoin (or fraction of a bitcoin) is secured by one or more cryptographic signatures. To transfer a bitcoin, you need to know its corresponding private key. And some of those keys have been lost—and it's impossible to know how many.