What a MAC Clause Actually Protects Against
Every M&A agreement includes a gap between signing and closing — often several months during which regulatory approvals, financing, and other conditions need to fall into place. A Material Adverse Change (MAC) clause, sometimes called a Material Adverse Effect (MAE) clause, is the buyer's contractual escape hatch if the target's business deteriorates severely enough during that gap. In principle, it lets the buyer walk away — or renegotiate — if something happens between signing and closing that meaningfully impairs the value of what they agreed to buy.
In practice, MAC clauses are written narrowly and interpreted even more narrowly by courts. Delaware, where most large public M&A agreements are litigated, sets an intentionally high bar: the decline has to be substantial relative to the target's overall long-term earnings power, and it has to be durationally significant — not a short-term dip the business is likely to recover from. On top of that, nearly every modern MAC clause carves out entire categories of events that don't count, no matter how severe: industry-wide downturns, general macroeconomic or political conditions, changes in law, and even the effects of the merger announcement itself.
Why MAC Clauses Are So Rarely Successful
The carve-outs exist because buyers and sellers both know that almost nothing forces a deal apart faster than uncertainty about whether it will close. Sellers negotiate broad carve-outs precisely so that ordinary business risk — a bad quarter, a shifting market, a recession — can't be used as a pretext to walk away after signing. As a result, only one buyer has ever won a fully litigated MAE case in Delaware: Akorn v. Fresenius (2018), where the target's earnings had collapsed by more than half over multiple quarters and, separately, was found to have committed serious regulatory and data-integrity violations. Every other buyer who has tried to invoke a MAC clause in Delaware — including in disputes far more severe than a routine bad quarter — has failed or settled before a ruling. For a full walkthrough of how the numeric threshold test works, see MAC Clause and Deal Closing Risk.
The Tiffany-LVMH Case: A MAC Clause in Action
The clearest recent example is LVMH's attempt to exit its $16.2 billion agreement to acquire Tiffany & Co. in 2020. Tiffany's sales fell roughly 29% year-over-year in the pandemic's worst quarter, and LVMH argued — among other things — that this qualified as a Material Adverse Effect. Tiffany sued in Delaware Chancery Court for specific performance, and LVMH countersued. But the case never reached a ruling: in October 2020, the two sides settled, with Tiffany accepting a price cut from $135.00 to $131.50 per share — a $425 million reduction — in exchange for LVMH dropping its objections and closing the deal.
That outcome is exactly the pattern the Delaware precedent would predict. A global pandemic hitting an entire industry is precisely the kind of macroeconomic, industry-wide event that standard MAC carve-outs are written to exclude, and by the time Tiffany sued, its sales were already recovering — undermining the "durationally significant" requirement. LVMH's pandemic-based MAE claim, on its own, was widely viewed by legal commentators as weak. What actually happened next is a case study in how MAC disputes get resolved in the real world: not by a judge, but by negotiation, with the mere threat of a costly, uncertain trial functioning as leverage even when the underlying legal claim is shaky. We break down the full numeric and legal analysis — including LVMH's separate, comparatively stronger argument that Tiffany breached its ordinary-course-of-business covenant by continuing to pay dividends during the pandemic — in MAC in Volatile Markets.
The Key Distinction Interviewers Test For
A MAC/MAE clause is not the only lever a buyer can pull if a target's behavior changes between signing and closing. Separately, most agreements include an ordinary-course-of-business covenant, which requires the target to keep operating consistent with its historical practice — regardless of whether its performance has actually suffered. This is a different, often easier claim to prove: it doesn't require showing the business was materially impaired, only that the target's conduct (capital allocation, dividends, hiring, capex) deviated from the past. Interviewers frequently test whether candidates can tell these two theories apart, since conflating them is one of the most common mistakes candidates make when discussing deal-break scenarios.