This study examines the effects of the 2016 Securities and Exchange Commission (SEC) reforms of Money Market Funds (MMFs) on the commercial paper market. By exploiting the differential time effect, we document a rise in the commercial paper (CP) rates. The rise in CP rates is more pronounced when the shadow floating NAV period starts and is similar across different types of commercial paper. Our cross-sectional analysis finds support for relationship-based lending in both commercial paper holdings and rates. We find that big issuers experienced a decrease and small issuers observed an increase in commercial paper outstanding from MMFs in the post-period. We find no evidence that rates vary across the size of the issuer in the post-period. Finally, financial institutions pay higher rates in the post-period than non-financial institutions.