Material Adverse Change Clause: What Qualifies, Carve-Outs, and Deal Certainty

A material adverse change (MAC) clause, also called a material adverse effect (MAE) clause, lets a buyer walk away from a signed deal if the target suffers a serious, durable hit to its business between signing and closing. In practice buyers have rarely succeeded in invoking it, because the carve-outs are broad and courts set the bar high. The clause is less a true exit and more a risk-allocation and renegotiation lever.

Reviewed and corrected on 12 October 2026. This is general information, not legal advice; check the cited statute or opinion before relying on it.

TL;DR

• A MAC clause gives the buyer the right to refuse to close (and sometimes terminate) if a material adverse change hits the target between signing and closing. It is a closing condition, not a price term.
• The bar is high. Delaware courts (and a Delaware Chancery court applying New York law in IBP) ask whether the change is consequential to the target's long-term earnings power over a period "measured in years rather than months," not a short-term dip. A buyer won on an MAE in Akorn (Del. Ch. 2018, affirmed), but lost in Hexion (2008) and Snow Phipps (2021).
• The carve-outs decide everything. General economic, industry, war, and pandemic effects are usually carved out, so the buyer can only invoke a MAC for harm that hits the target disproportionately compared to its peers.
• A MAC is mostly a renegotiation lever. A buyer with cold feet has rarely won a MAC fight outright, but the threat can reopen price or terms.
• The most consequential drafting point is the disproportionate-effect qualifier on the carve-outs: it is the narrow path back to the buyer when a carved-out event hits the target far harder than the rest of its industry.

What a material adverse change clause actually does

A MAC clause appears in two places in an acquisition agreement, and they do different work.

1. As a closing condition. The buyer's obligation to close is conditioned on no MAC having occurred since signing. If a MAC happens, the buyer can refuse to close without breaching. This is the buyer's main escape hatch between signing and closing.

2. As a qualifier on the seller's representations. Many reps are qualified by materiality or MAE, so a small inaccuracy does not give the buyer an out, only an inaccuracy that rises to a material adverse effect does. This is the "bring-down" at closing.

The defined term itself has three parts: the general standard (a change materially adverse to the business, results, or condition of the target), the carve-outs (categories of events that do not count), and the exceptions to the carve-outs (the disproportionate-effect qualifier that pulls some carved-out harm back in). The negotiation lives in the second and third parts.

Why it matters: the dollars at stake

Picture (a hypothetical) buyer signing to acquire a target for $500,000,000. Between signing and closing, the target loses its largest customer, which had been roughly 35% of revenue, and the loss looks permanent.

• If the lost customer is judged a durationally significant hit to the target's long-run earnings power and is specific to the target (not an industry-wide trend), the buyer may have a credible MAC and can refuse to close or push to renegotiate the $500,000,000 price.
• If the same revenue drop comes from an industry-wide downturn that hit every peer, it likely falls inside the general-economic or industry carve-out, and the buyer has no MAC, even though the dollar impact is identical. The buyer must close at $500,000,000.

Same revenue hit, opposite outcomes. The cause and its durability, not the size of the number, decide whether the buyer is bound. That is why the carve-outs and the disproportionate-effect qualifier are the most fought-over words in the clause.

Who wants what

The pattern: buyers want a flexible, forward-looking standard with few carve-outs so they retain optionality; sellers want deal certainty, a narrow standard, broad carve-outs, and ideally a hard number so everyone knows where the line is.

Market-standard language

A defined MAE term in a US acquisition agreement reads close to this:

"Material Adverse Effect" means any change, event, or effect that is
materially adverse to the business, financial condition, or results of
operations of the Company and its subsidiaries, taken as a whole;
provided, however, that none of the following will be deemed to constitute
a Material Adverse Effect: (a) changes in general economic or political
conditions; (b) changes affecting the industries in which the Company
operates generally; (c) changes in applicable law or accounting rules;
(d) acts of war, terrorism, or natural disaster, including epidemics or
pandemics; (e) the announcement or pendency of the transactions
contemplated by this Agreement; or (f) any failure to meet internal or
published financial projections (though the underlying cause may be
considered);

provided further that clauses (a) through (d) will be taken into account
in determining whether a Material Adverse Effect has occurred to the extent
they have a disproportionate effect on the Company relative to other
participants in the same industry.

The "provided further" sentence is the buyer's lifeline. It says the carved-out events (economy, industry, war, disaster) still count if they hit the target much harder than its peers. Without it, a buyer can never invoke a MAC for any broad event, no matter how badly the target was singled out.

The negotiation: standard, fallback, walk-away

Treat the general standard, the carve-outs, and the disproportionate qualifier as three separate trades.

The workhorse compromise: a standard tied to the company's own business and results (not "prospects"), the usual carve-outs, and a disproportionate-effect qualifier that lets the buyer reach harm that singled the target out.

Common carve-outs / variations

The carve-out list is where most MAC negotiation happens. The standard categories:

• General economic and political conditions. Recessions, interest-rate moves, market swings.
• Industry-wide changes. Anything affecting the target's whole sector, not just the target.
• Changes in law or accounting rules. New regulation or GAAP changes the seller cannot control.
• War, terrorism, natural disaster, pandemic. Often updated after recent events to name pandemics and epidemics explicitly.
• The deal itself. The announcement or pendency of the transaction, since customers or employees may react to the deal.
• Failure to meet projections. Carved out, but with the important caveat that the underlying cause of the miss may still be examined.

The disproportionate-effect qualifier, the variation that most affects the buyer's leverage, reads like this:

except, in the case of clauses (a) through (d), to the extent such change,
event, or effect has a disproportionate adverse effect on the Company and
its subsidiaries, taken as a whole, relative to other participants in the
industries in which the Company operates, in which case only the
incremental disproportionate impact may be taken into account.

Jurisdiction and enforceability notes

MAC clauses are enforceable, but the standard for proving one is demanding, and the governing law and the exact wording matter. We read the opinions below in October 2026.

• The standard. In In re IBP, Inc. Shareholders Litigation, 789 A.2d 14 (Del. Ch. 2001), which applied New York law, the court read a broad MAE condition as "a backstop protecting the acquiror from the occurrence of unknown events that substantially threaten the overall earnings potential of the target in a durationally-significant manner," and said "[a] short-term hiccup in earnings should not suffice." It found no MAE. Hexion Specialty Chemicals, Inc. v. Huntsman Corp., 965 A.2d 715 (Del. Ch. 2008), applied Delaware law, adopted the same "years rather than months" framing, found no MAE, and placed the burden of proving an MAE on the party seeking to excuse its performance "absent clear language to the contrary."
• A buyer can win. In Akorn, Inc. v. Fresenius Kabi AG (Del. Ch. Oct. 1, 2018, C.A. No. 2018-0300-JTL), the court found a general MAE based on a sustained, durationally significant decline in Akorn's performance after signing, and also held that Akorn's breach of its regulatory-compliance representations would reasonably be expected to produce an MAE. The Delaware Supreme Court affirmed by order on December 7, 2018 (198 A.3d 724), saying the record supported both the MAE finding and the termination for breach of the regulatory representations.
• Pandemic cases. In AB Stable VIII LLC v. MAPS Hotels and Resorts One LLC (Del. Ch. Nov. 30, 2020, 2020 WL 7024929), the court found that COVID-19 fit the sale agreement's MAE exception for "natural disasters and calamities," so there was no MAE as defined, but the buyer could still terminate because the seller's pandemic response breached the ordinary-course covenant. The Delaware Supreme Court affirmed on December 8, 2021 (No. 71, 2021), holding that the MAE provision and the ordinary-course covenant serve different purposes and that the parties could have limited the covenant to MAE-level events but did not. In Snow Phipps Group, LLC v. KCAKE Acquisition, Inc. (Del. Ch. Apr. 30, 2021, C.A. No. 2020-0282-KSJM), the court held the sellers proved there was no MAE given "the durational insignificance and corresponding immateriality of the decline in sales," that a government-orders exception applied, and that the target had not suffered disproportionately to comparable companies.
• Carve-outs are read as written. If an event falls within a carve-out, it does not count toward an MAE unless a disproportionate-effect qualifier applies. Many agreements, like the sample above, then count only the incremental disproportionate impact. Read the clause, because that last point is a drafting choice, not a rule of law.
• Remedies depend on the agreement. Whether a seller can force a reluctant buyer to close depends on the specific-performance and termination-fee provisions. In Snow Phipps the court entered judgment for specific performance of the purchase agreement. In Hexion the agreement allowed specific performance of the buyer's covenants but not of the obligation to close, and the court's order enforced the covenants. A buyer should not assume it can pay a break fee and leave.
• Forward-looking language. Words like "prospects" expand the clause toward the future and are heavily negotiated; sellers resist them because they make a missed forecast easier to frame as a MAC. This is a drafting point; we did not find a case that turns on it.

This is general information, not legal advice for a specific deal. Whether a MAC has occurred turns on the governing law and the specific facts; confirm against the controlling law before you rely on it. MAC analysis is core to deal diligence; see our M&A due diligence legal workstream checklist and our guide on drafting the schedule of exceptions.

Review checklist: red flags to catch

• The carve-outs are absolute with no disproportionate-effect qualifier, so the buyer can never invoke a MAC for any broad event.
• The general standard includes "prospects" (buyer-friendly) or omits it (seller-friendly); know which side you are on.
• Failure to meet projections is treated as a MAC on its own, rather than carved out with the cause still examinable.
• The clause has a low numeric threshold that turns ordinary volatility into an exit right.
• The MAC qualifier on the reps is inconsistent with the standalone closing-condition MAC, creating two different standards.
• No pandemic or epidemic carve-out in a deal where that risk is live, leaving an old gap.
• The buyer relies on the MAC as a real exit when the facts and the case law make a walk unlikely.
• The interim-operating covenants do not line up with the MAC, so conduct that hurts the business is neither a covenant breach nor a clear MAC. In AB Stable the buyer's way out was the ordinary-course covenant, not the MAE.

How it interacts with other clauses

A MAC clause connects to several others. Read it together with:

• Representations and warranties: many reps are qualified by MAE, so the standard defines how much inaccuracy the buyer must tolerate at the bring-down.
• Termination: the MAC closing condition is usually paired with a termination right if closing does not occur by the outside date.
• Change of control: the deal itself is typically carved out of the MAC, while change-of-control terms in the target's own contracts may be part of the diligence.
• Force majeure: both deal with intervening events, but force majeure excuses performance while a MAC excuses closing; keep their event lists coherent.
• Indemnification: post-closing, materiality and MAE qualifiers interact with how indemnity claims are measured.

For deal-context review, see our M&A due diligence legal workstream checklist.

FAQ

What is a material adverse change clause? It is a provision in an acquisition agreement that lets the buyer refuse to close, and sometimes terminate, if the target suffers a serious, durable hit to its business between signing and closing. It works as a closing condition and as a qualifier on the seller's representations.

What is the difference between a MAC and a MAE? The two terms are usually used interchangeably, and the agreement typically defines one and uses it throughout, so read the defined term. Both are generally applied under the same demanding standard for serious harm to the target.

How hard is it to prove a material adverse change? Hard. In the Delaware cases above, the question is whether the change is durationally significant and consequential to long-term earnings power, with the expected period "measured in years rather than months." Buyers lost on the MAE question in Hexion, AB Stable (where the buyer still won on the ordinary-course covenant) and Snow Phipps, and won in Akorn. Absent clear contract language, the party seeking to excuse its performance carries the burden (Hexion).

What are typical MAC carve-outs? General economic and political conditions, industry-wide changes, changes in law or accounting rules, war, terrorism, natural disasters and pandemics, the announcement of the deal itself, and failure to meet financial projections. These usually come back with a disproportionate-effect qualifier.

What is the disproportionate-effect qualifier? It is an exception to the carve-outs: even a carved-out event (a recession, an industry slump, a pandemic) can count toward a MAC if it hits the target much harder than its industry peers. It is the buyer's main path back to a MAC after broad events are carved out.

Can a buyer use a MAC to walk away from a deal? Rarely outright. Buyers have seldom won a MAC fight, and in Snow Phipps the court ordered the buyers to close. Akorn shows it can work on strong facts. In practice a MAC often works as a renegotiation lever: the threat of a fight can reopen price or terms even when an actual walk would fail.

Does failure to meet financial projections count as a MAC? On its own, usually no. Most clauses carve out failure to meet internal or published projections, since forecasts are inherently uncertain. The important caveat is that the underlying cause of the miss may still be examined to see whether it independently amounts to a MAC.

Arshita Anand

Co-Founder & CEO · Attorney

Arshita leads product and strategy at Vaquill AI, the US primary law data API. As an attorney, she decides which law we carry, how each section is sourced and cited, and what legal AI and compliance teams need from the data.