Core contract language · Working
Material adverse change
Also called: MAC, material adverse effect, MAE
ELI5
A materially harmful change defined by transaction documents, often allowing specified rights.
Used in conversation
“Can we circulate material adverse change with the assumptions and open questions marked?”
Pitch context
You will see “Material adverse change” in board papers, contracts, policies, risk registers and compliance reports when the discussion reaches core contract language.
Why it matters: In core contract language, a loose definition can change rights, obligations, approval, disclosure or enforceability.
Caution
Meaning, enforceability and required process vary by jurisdiction and agreement; this definition is not legal advice.
Connected terms
- Marginal abatement costThe search label “MAC” can route to both entries.
- Minimum annual commitmentThe search label “MAC” can route to both entries.
Sources & evidence · 4
Direct term-level sources and supporting source families.
- OECD — G20/OECD Principles of Corporate Governance 2023Direct source · institutional · checked 2026-08-16
- U.S. Acquisition.gov — Federal Acquisition Regulation Part 15 — Contracting by NegotiationDirect source · primary · checked 2026-08-16
- U.S. Securities and Exchange Commission — EDGAR and filing resourcesSupporting source family · primary · checked 2026-08-16
- National Institute of Standards and Technology — Computer Security Resource Center GlossarySupporting source family · primary · checked 2026-08-16