Payment stablecoins and MMFs share a crucial structural similarity in their susceptibility to run risk during financial stress. Both are designed to provide investors with a stable, cash equivalent asset, backed by underlying reserves — but neither is explicitly guaranteed by the government. As policymakers consider stablecoin regulations, it is essential to recognize the parallels between stablecoins and MMFs, particularly regarding run risks and potential threats to financial stability. Drawing on lessons from past MMF reforms, regulators have the opportunity to craft a regulatory framework for stablecoins that mirrors the credit and liquidity safeguards applied to MMFs. To mitigate systemic vulnerabilities, stablecoin regulation could include the following provisions: Credit quality requirements for reserve assets backing payment stablecoins; Prescriptive reserve composition standards, limiting assets to cash and high-quality liquid securities; Liquidity requirements, such as a minimum percentage of reserves in daily and weekly liquid assets; Maturity limits on reserve assets to reduce duration risk; Liquidity fees triggered when liquid assets fall below predefined thresholds; Custodian requirements mandating securities and other noncash assets reserves be held at regulated custodians; Cash reserves mandated to be deposited at FDIC-insured banks; Daily disclosure of the reserve assets with monthly audits, published on the issuer’s website to enhance transparency; Prohibition on the payment stablecoin issuer lending reserve assets or using reserve assets as collateral; Requiring issuers to assess through stress tests their ability to maintain a $1 net asset value under adverse scenarios;. By drawing on the regulatory lessons learned from MMFs, policymakers have an opportunity to get ahead of the curve. Implementing sensible, risk-based safeguards for stablecoins will not only protect investors and preserve financial stability but also foster growth in the digital asset space. With proactive regulation, the promise of stablecoins can be realized without repeating past mistakes.