A key category of DeFi applications offer overcollateralized loans, including MakerDAO, Compound, and dYdX. Such applications function by incentivizing a variety of third-party actors to liquidate collateral on loans that have fallen below a collateralization ratio, repay the original lender, and collect a fee. While these applications have a wide variety of specific features to support such systems, this study highlights the emergence and scale of opportunity for these third-party liquidators. Using on-chain data, the author estimates that $5m in profit has been made by these bots since 2018; roughly 150 bots are active today. These profit margins may shrink as more bots enter the market, new tools are developed to minimize the risk of liquidation, and protocols experiment with various dynamic liquidation systems.