Derivatives is a difficult to asses market, in terms of size. For example, the largest derivatives markets out there - interest rate swaps - trade contracts that usually have ~zero net value at the beginning of their lives, when the sides open the contract. Derivatives typically start small and sometimes end up huge.
The investable universe looks something like that:
The investable universe looks something like that:
https://imgur.com/a/68U3LsZ