DeFi Protocols for Loanable Funds: Interest Rates, Liquidity and Market\n Efficiency

Abstract

We coin the term *Protocols for Loanable Funds (PLFs)* to refer to protocols\nwhich establish distributed ledger-based markets for loanable funds. PLFs are\nemerging as one of the main applications within Decentralized Finance (DeFi),\nand use smart contract code to facilitate the intermediation of loanable funds.\nIn doing so, these protocols allow agents to borrow and save programmatically.\nWithin these protocols, interest rate mechanisms seek to equilibrate the supply\nand demand for funds. In this paper, we review the methodologies used to set\ninterest rates on three prominent DeFi PLFs, namely Compound, Aave and dYdX. We\nprovide an empirical examination of how these interest rate rules have behaved\nsince their inception in response to differing degrees of liquidity. We then\ninvestigate the market efficiency and inter-connectedness between multiple\nprotocols, examining first whether Uncovered Interest Parity holds within a\nparticular protocol and second whether the interest rates for a particular\ntoken market show dependence across protocols, developing a Vector Error\nCorrection Model for the dynamics.\n