TLDR:
A Material Adverse Change (MAC) clause—also called Material Adverse Effect (MAE)—is a contractual provision in M&A transactions that allows the buyer to terminate the deal, renegotiate terms, or refuse to close if specified adverse events occur between signing and closing. MAC clauses allocate the risk of negative business changes during the signing-to-closing period.
Defining Materiality
MAC clauses must define “material” carefully—courts have been notoriously reluctant to find that events constitute MACs absent specific definition. The seminal Delaware case (Akorn v. Fresenius, 2018) found a MAC for the first time in Delaware history when EBITDA dropped 86% post-signing. More recent COVID-era cases (Snow Phipps v. KCAKE Acquisition, AB Stable v. MAPS Hotels) provided additional guidance: short-term financial impact is insufficient, materiality must reflect “durationally significant” effects, and ordinary cyclical or temporary disruptions don’t qualify. Practitioners typically combine objective (quantitative thresholds) and subjective (commercially reasonable judgment) materiality standards.
Standard MAC Exclusions
Modern MAC clauses typically include extensive exclusions defining what does NOT constitute a MAC: macroeconomic conditions (general economic, industry, market changes), regulatory changes affecting all participants, political or geopolitical events, natural disasters and pandemics (now explicitly addressed post-COVID), changes in accounting principles or law, the announcement of the transaction itself, and seller compliance with the agreement. These exclusions allocate “general” risks to the buyer while preserving MAC protection for target-specific adverse events.
Negotiation and Practice
MAC negotiations balance buyer protection (broader, easier-to-trigger MAC) against seller deal certainty (narrower, harder-to-trigger MAC). In tight seller markets, MAC clauses skew narrow with extensive exclusions; in buyer’s markets, the reverse. Modern MAC drafting typically includes: prospective effects test (impact must reasonably be expected to be material going forward, not just historic), durationally significant qualifier, materiality threshold either quantitative or qualitative, and specific exclusions. Founders entering M&A negotiations should understand that MAC clauses primarily protect buyers and that broad MAC definitions can be used opportunistically by buyers experiencing buyer’s remorse—not just for legitimate target-specific adverse events.