A large alternative asset class you probably haven’t heard of is litigation financing – “transactions in which a third party provides capital (debt, equity, or a hybrid) to one of the parties to a legal claim (a plaintiff or law firm) in exchange for a financial interest derived in part from the outcome of the claim.“
This is an excellent comprehensive up to date paper on this sector. The full paper is here and a great summary is here.
The asset class is estimated to boast 20%+ returns and has grown to a dedicated AuM of $12bn.