“Reasonable best efforts” is an M&A covenant that sits between a pure “efforts” promise and an absolute obligation. It requires a party to take the actions a reasonable, similarly situated buyer or seller would take to achieve a specified outcome, typically regulatory approvals, financing, or other closing conditions, without sacrificing the core economics of the deal unless the contract says otherwise. For finance professionals, this clause becomes the standard applied when a deal fails to close and one side claims the other did not try hard enough. It shapes day-to-day decisions in the interim period, influences whether you collect a reverse break fee or face specific performance, and determines whether your IC’s greenlight turns into litigation exposure.
The practical question is not whether a party worked hard. The question is whether the party took the steps the agreement implied, within the constraints it also implied, and whether it avoided steps that would foreseeably frustrate the objective.
Reasonable best efforts is operational and economic, not just legal. It affects how you price closing risk, how you set your base case timeline, and how you write the downside section of an IC memo. It also affects how lenders, co-investors, and management teams perceive execution credibility during the signed-but-not-closed period.
In practice, the clause often becomes a proxy for intent. If a buyer’s incentives shift after signing (macro moves, EBITDA slips, financing tightens), the seller will read the efforts covenant as a promise to push through friction rather than wait it out. That is why finance professionals should treat “reasonable best efforts” like a deliverable with owners, milestones, and documentation, not a generic statement of good behavior.
Reasonable best efforts appears most often in covenants to obtain antitrust or foreign investment approvals, prepare and file regulatory submissions, secure debt financing and keep commitments in place, and cause affiliates or portfolio companies to do things the signing party does not fully control. It also governs efforts to satisfy commercially reasonable conditions such as third-party consents, maintain the business in ordinary course until closing, and coordinate with agencies.
The clause is usually paired with cooperation covenants. Cooperation language allocates who drafts filings, who controls messaging, who pays fees, and who bears the burden of remediation. Without those allocations, reasonable best efforts becomes a litigation proxy for “who should have done what,” and your deal team ends up debating process instead of outcomes.
Reasonable best efforts is a diligence standard, not a guarantee. Performance is evaluated based on what a reasonable party would do at the time, not with hindsight. The most common evidence is mundane: calendars, filing drafts, escalation emails, lender update calls, and whether senior decision-makers were actually engaged.
It is not a “hell or high water” commitment to do whatever it takes, including divestitures or behavioral remedies, unless explicitly stated. It is not a promise to accept any regulatory remedy or pay any price for consents. It is not a duty to litigate to the end absent an express litigation covenant. And it is not a substitute for conditions precedent: if closing is conditional on approval, the covenant is usually the promise to pursue it, not to obtain it at all costs.
It also is not a safe harbor. A party can show high activity and still breach if key steps were omitted, delayed, or structured in a way designed to fail.
Reasonable best efforts disputes usually reflect misaligned incentives after signing. A buyer with optionality may prefer delay, especially if financing is stressed or the business underperforms. A seller may want a fast closing and may push for more aggressive regulatory concessions. Lenders may have outs that are not mirrored in the merger agreement, creating a coordination problem for a buyer’s financing efforts. Sponsors may face fund-level constraints, portfolio concentration limits, or IC conditions that influence behavior.
Because the standard is flexible, it can be argued from the paper trail. A party rarely admits it wanted to walk. The record becomes a proxy for intent, and that is why execution discipline is a finance workstream, not just a legal one.
Finance teams often treat closing risk as a single probability and move on. Reasonable best efforts is where that probability becomes a governance and cost question: what do you have to do (and pay) to keep the deal “live,” and what is the expected value of doing so?
In an IC memo, the practical output is a cleaner “execution plan” section: identify the gating approvals, who owns them, what concessions you are willing to make, and what you are not willing to make. If you cannot state that clearly, you are not underwriting the efforts covenant you are signing.
Antitrust is where reasonable best efforts is most litigated because outcomes are uncertain and remedies can be expensive. The covenant is usually paired with one of three burden allocations: hell or high water (buyer accepts any remedy), reasonable efforts with remedy limits (buyer accepts remedies up to a threshold), or cooperation only (no forced divestitures without consent).
If the deal has significant overlap, a seller should treat an uncapped reasonable best efforts covenant as economically similar to hell or high water in practice. A buyer will be pressured to concede remedies because otherwise it risks an efforts breach, reverse termination fee exposure, and reputational damage. A related operational point is control: if the agreement does not specify who controls remedy negotiations, you can end up with parallel strategies and inconsistent messaging, which raises both delay and enforcement risk.
For a deeper view of why process matters in U.S. antitrust, see Second Request dynamics.
Foreign investment regimes and sector regulators create a different problem: mitigation can include governance controls, information barriers, supply commitments, or restrictions that effectively change the asset you thought you were buying. Reasonable best efforts covenants should clarify whether the buyer must offer mitigation measures, whether the seller must agree to operational restrictions post-closing, and whether the buyer can restructure ownership or governance to secure approval.
For cross-border execution, the commercial takeaway is simple: if mitigation terms can reduce cash generation or constrain the exit universe, they belong in the underwriting memo and the model, not buried as “legal process.” Cross-border teams often benefit from a dedicated diligence view of approvals alongside other cross-border M&A considerations.
Buyers often promise reasonable best efforts to obtain debt financing when the seller relies on leverage to get paid at closing. This is most acute when there is a separate debt commitment letter and the merger agreement limits the buyer’s ability to walk.
Key components of a financing efforts package include commitment letters executed at signing with conditions aligned to the acquisition agreement, cooperation covenants requiring the seller to provide financial statements and other deliverables, a definition of “Financing” that limits the buyer’s obligation to the committed debt, and sometimes an alternative financing covenant that may require the buyer to seek replacement financing if the original commitments fail.
Reasonable best efforts does not mean the buyer must accept any replacement debt at any price. But if the agreement includes an alternative financing covenant, the buyer may need to pursue market solutions that are reasonably available, including paying incremental fees or accepting tighter covenants, unless the agreement caps those concessions. For sponsors and leveraged finance teams, this is where the merger agreement meets the reality of lender flex and closing mechanics, including debt scheduling and funding steps that should be reflected in the model (see debt scheduling).
Reasonable best efforts is operational. It requires a workplan, owners, and controls. A buyer seeking to demonstrate compliance typically maintains a regulatory matrix with triggers, deadlines, and responsible parties; a decision log for remedy discussions with escalation points; a communications protocol with the seller including draft-sharing and notice triggers; and internal resourcing and outside counsel engagement that matches the deal timeline.
The seller’s performance typically focuses on cooperation and information production. The seller should track data room completeness against filing needs, management availability for regulator interviews and third-party outreach, and consents and waivers processes with escalation paths. When disputes arise, contemporaneous evidence of a credible process matters more than a post hoc narrative.
Reasonable best efforts is workable when paired with clear objectives, decision rights, remedy boundaries, and a process that can be proven. For finance professionals, the career-relevant move is to treat the clause like underwriting: map it into timelines, scenarios, and cash flows, assign owners, and document decisions. That approach produces cleaner IC memos, more accurate models, and fewer expensive surprises when incentives shift after signing.
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