Similar to the more traditional money market funds (MMFs), stablecoins aim to provide investors with safe, money-like assets. We investigate similarities and differences between these two investment products. Like MMFs, stablecoins suffer from “flight-to-safety” dynamics: we document net flows from riskier to safer stablecoins on days of crypto-market stress and estimate a discrete “break-the-buck” threshold of $1, below which stablecoin redemptions accelerate. We then focus on two specific stablecoin runs, in 2022 and 2023, showing that the same flight-to-safety dynamics also characterized these episodes. Finally, as flight-to-safety flows occur within MMF families, stablecoin flows tend to happen within blockchain.