Provision that automatically raises the existing loan's spread if a subsequent incremental facility (accordion) is priced at a wider spread — typically to within 50 bps of the incremental spread. Protects existing lenders from being disadvantaged when the borrower issues new debt under the same credit agreement at less attractive terms. MFN clauses commonly sunset after 12–18 months and may carve out small (25–50 bps) cushions.