Based on comments here, because they called it “staking as a service”.

But apparently that nomenclature bypasses this very clear and explicit definition

“The term ‘‘exchange’’ means any organization, associa- tion, or group of persons, whether incorporated or unincor- porated, which constitutes, maintains, or provides a market place or facilities for bringing together purchasers and sellers of securities or for otherwise performing with respect to securi- ties the functions commonly performed by a stock exchange as that term is generally understood, and includes the market place and the market facilities maintained by such exchange.”