Mergers & Acquisitions (M&A): Locked-box vs Completion Accounts

Structuring Closing Mechanisms in M&A

Introduction: Purpose and Scope of Closing Mechanisms in M&A

In a mergers and acquisitions (M&A) transaction, determining the valuation is only one step in the overall process. Once the Enterprise Value has been negotiated, the critical issue becomes its effective implementation at the time ownership is transferred. In other words, how can the parties ensure that the price accurately reflects the economic position of the company at the moment the buyer takes control?

This is precisely the role of closing mechanisms. These mechanisms are not intended to recalculate the company’s value, but rather to contractually organize how the negotiated price is executed and, where appropriate, adjusted. They determine the point in time at which the financial situation is fixed, how economic risk is allocated between signing and closing, and how potential variations in net debt or working capital are treated.

European transactional practice has progressively established two dominant structures: the Completion Accounts mechanism, based on a post-closing price adjustment using accounts prepared as of the completion date, and the Locked-box mechanism, which fixes the price based on historical financial statements dated prior to closing. As noted in various professional analyses, including those published by PwC, these approaches primarily reflect different allocations of economic risk between seller and purchaser.

The core issue is therefore not valuation itself, but the protection and execution of the negotiated price. Should the parties opt for an ex post adjustment to achieve maximum accounting precision, at the cost of temporary uncertainty for the seller? Or should the price be crystallized at an earlier date, in exchange for a transfer of economic risk between signing and closing?

This publication first examines the concept of a closing mechanism, the rationale for its implementation in a corporate transaction, and the legal and financial bases required for its structuring. It then analyzes in detail the Locked-box mechanism — its origins, conditions of application, complementary features and limitations — before addressing the Completion Accounts mechanism from a symmetrical perspective. Finally, a practical case illustrates Hectelion’s approach to structuring transactions, followed by a personal perspective from the managing director on the balance to be achieved between legal certainty and operational fluidity.

What Is a Closing Mechanism?

In an M&A transaction, closing refers to the legal act through which the effective transfer of shares or assets occurs, together with payment of the corresponding purchase price. It materializes the completion of the transaction following the signing of the acquisition agreement (Share Purchase Agreement or Asset Purchase Agreement) and, where applicable, the satisfaction of conditions precedent.

However, while closing marks the legal transfer of ownership, it does not by itself resolve a key issue: the exact economic situation of the company at the time of transfer. Between signing and completion, the company continues to operate. Its cash position evolves, indebtedness changes, and working capital fluctuates. In most transactions, the price is based on financial metrics such as net debt or a normalized level of working capital.

The closing mechanism is therefore the contractual architecture that articulates these elements. It organizes how the negotiated price will be executed and, where appropriate, adjusted to reflect economic reality at a defined reference date. It does not alter the company’s valuation as such; rather, it defines how that valuation is implemented.

International practice shows that two principal approaches dominate. The first consists of adjusting the price after closing based on accounts prepared as of the effective transfer date (Completion Accounts). The second consists of fixing the price based on earlier financial statements, transferring economic risk between that date and closing (Locked-box).

A closing mechanism may therefore be defined as the set of contractual provisions determining the economic reference date, allocating financial risk between the parties, and legally securing execution of the price. It lies at the core of the acquisition agreement and often determines the final economic balance of the transaction.

This definition illustrates that the closing mechanism is not a minor technical aspect of the SPA. It is a structural component of the transaction, with effects that may represent several percentage points of equity value. The question is not whether to include a closing mechanism, but how to design it consistently with the company’s profile, the competitive context of the process, and the parties’ risk appetite.

Why Implement a Closing Mechanism?

In an M&A transaction, the negotiated price is generally based on financial data prepared at a specific date — annual accounts, interim accounts, or a dedicated financial statement. Between that reference date and closing, however, the company continues operating. It collects receivables, pays suppliers, incurs or repays debt, and may distribute dividends. This operational dynamic creates a time gap between valuation and effective transfer of control.

Without a closing mechanism, this gap would generate significant uncertainty: the buyer might pay for a financial position that no longer exists, while the seller could face a price challenge despite no longer controlling the company. The closing mechanism is designed precisely to neutralize this uncertainty by contractually organizing the economic transition between signing and closing.

The central issue is risk allocation. Who bears changes in cash, indebtedness, or working capital during the interim period? The chosen mechanism answers this question either by crystallizing the price in advance or by adjusting it based on the actual situation at the time of transfer.

Beyond financial metrics, the implementation of a closing mechanism also serves legal certainty. The acquisition agreement must clearly define calculation methods, applicable accounting standards, deadlines for preparing accounts, and dispute resolution procedures. Absent such clarity, litigation risk increases significantly. Professional studies consistently show that price adjustment disputes rank among the most common sources of post-closing conflicts in mid-market transactions.

A closing mechanism also facilitates transactional fluidity. In a competitive process, price certainty can be a strategic advantage for the seller; conversely, in a bilateral transaction with accounting uncertainties, a precise adjustment mechanism can reassure the buyer and support deal execution. The choice of mechanism is therefore not neutral: it affects negotiation dynamics, timing, and even risk perception.

Ultimately, a closing mechanism does not modify intrinsic valuation. Its function is to ensure consistency between negotiated value and economic reality at transfer, while contractually allocating interim risks. This balance between financial precision and legal certainty is one of the most sensitive equilibrium points in any M&A transaction.

How and on What Basis Should a Closing Mechanism Be Implemented?

The implementation of a closing mechanism is neither automatic nor merely a matter of market practice. It requires prior analysis of the nature of the target company, the quality of available financial information, the competitive context of the transaction, and the profile of the parties involved.

In practice, the first basis of analysis is accounting and financial. The selected mechanism must rely on clearly defined financial metrics: net debt, available cash, a normalized level of working capital, and, where relevant, equivalent items (quasi-equity, deferred tax liabilities, specific provisions). The absence of precise definitions for these items constitutes one of the primary sources of post-closing disputes. Professional guidance consistently emphasizes the importance of contractually formalizing calculation methodologies, applicable accounting standards, and the accounting principles to be applied.

The second basis is temporal. It is essential to determine the date at which the economic reference position will be fixed. This decision directly affects the allocation of risk between the parties. If the chosen date corresponds to a historical financial position prior to closing, the seller achieves greater price certainty; if it corresponds to the effective transfer date, the buyer benefits from a more accurate snapshot of the company’s financial position at the time control is acquired.

The third basis is legal. The acquisition agreement must organize in detail the practical execution mechanics: deadlines for preparing the closing accounts, notification and dispute procedures, potential appointment of an independent expert, escrow or blocked account arrangements, and financial settlement mechanics. Under Swiss law, these provisions fall within the general principle of contractual freedom enshrined in the Swiss Code of Obligations, subject to compliance with the overarching principles of good faith and proper performance.

Beyond technical considerations, the choice of mechanism also depends on the transactional context. In a competitive process involving investment funds, the search for certainty and speed may favor a locked-box structure. Conversely, in a bilateral transaction involving a company with significant working capital volatility or sector-specific complexities, a post-closing adjustment mechanism may be more appropriate.

Finally, the quality of financial information is a determining factor. Audited accounts, a stable financial track record, and operational visibility strengthen the case for a mechanism fixed at an earlier date. Conversely, incomplete documentation or a transitional financial situation increases the need for an adjustment mechanism that reflects economic reality at the time of transfer.

Implementing a closing mechanism therefore involves balancing certainty and precision, speed and control, contractual simplicity and economic protection. This balancing exercise cannot be standardized; it must be tailored to the specific transaction at hand. It is within this framework that the two principal models examined below — the Locked-box and the Completion Accounts — each embody a distinct philosophy of transactional risk management.

The Locked-box Mechanism

Origin and Development

The Locked-box mechanism originates from Anglo-Saxon transactional practice, particularly from UK private equity transactions in the 1990s. Faced with competitive processes requiring both speed and price certainty, investment funds progressively favored a structure that eliminated post-closing adjustments and subsequent discussions over completion accounts.

The model subsequently spread across continental Europe, notably in mid-market transactions and structured sales processes involving multiple bidders. Professional analyses indicate that the locked-box mechanism has become widely dominant in sponsor-to-sponsor transactions and in competitive auction environments.

Its success is based on a simple promise: to provide price certainty at signing and eliminate uncertainty linked to post-closing adjustments.

Definition and General Principle

The Locked-box mechanism consists of definitively fixing the price based on historical financial statements prepared at a date prior to closing — the “Locked-box date.” From that date onward, the price is considered economically earned by the seller, even though legal ownership transfers at a later point.

In practice, Enterprise Value is determined based on the reference accounts. Net debt and, where applicable, working capital are assessed at that date. No further revision is made at closing.

Economic risk between the Locked-box date and closing is therefore transferred to the buyer, subject to a fundamental commitment from the seller: the absence of value leakage.

Conditions for Application

The use of a Locked-box structure requires certain preconditions.

First, the reference financial statements must be reliable — ideally audited — and accurately reflect the company’s economic position. Insufficient accounting quality mechanically weakens the mechanism.

Second, the business must demonstrate relative operational stability. Significant volatility in working capital or exceptional events occurring after the reference date may increase the risk borne by the buyer.

Finally, the data room must allow for detailed analysis of cash flows between the Locked-box date and closing. The mechanism relies on enhanced financial transparency, as the buyer accepts interim economic risk.

Complementary Mechanisms and Associated Clauses

The Locked-box mechanism does not operate in isolation. It is structured through a series of contractual provisions governing the interim period.

The central concept is “leakage.” Leakage refers to any transfer of value to the seller or its affiliates after the Locked-box date. This may include dividends, shareholder loan repayments, exceptional payments, or transactions outside the ordinary course of business.

The agreement typically distinguishes between “permitted leakage” — explicitly identified and factored into price negotiations — and prohibited leakage, which must be fully reimbursed to the buyer.

Another frequently observed mechanism is the “ticking fee,” a compensatory payment granted to the seller for the period between the Locked-box date and closing, often calculated as an interest rate applied to the purchase price. This reflects the principle that the seller is economically deprived of its asset from the reference date onward.

The agreement also generally includes an “ordinary course of business covenant” to prevent material modifications to the financial or operational structure prior to closing.

Advantages

The primary advantage of the Locked-box mechanism lies in price certainty. From signing, the seller knows the exact amount it will receive, without exposure to post-closing accounting adjustments.

The mechanism simplifies the post-closing phase. The absence of completion accounts reduces litigation risk and facilitates a smoother transition.

In competitive processes, this certainty is often decisive, allowing sellers to compare offers on a clear and executable basis.

Limitations and Points of Attention

The Locked-box structure transfers part of the economic risk to the buyer. If the company’s financial position deteriorates between the reference date and closing, no automatic adjustment benefits the buyer.

The mechanism also requires precise drafting regarding leakage definitions and interim covenants. Ambiguities may paradoxically generate disputes.

Finally, it is not suitable for all situations. In complex carve-outs, high-growth companies, or contexts of financial uncertainty, the absence of post-closing adjustment may hinder negotiations.

The Completion Accounts Mechanism

Origin and Development

The Completion Accounts mechanism predates the Locked-box and also originates from Anglo-Saxon practice. It established itself as the traditional model in bilateral transactions, particularly where the company’s financial position may materially evolve between signing and completion.

Unlike the Locked-box, which prioritizes ex ante certainty, Completion Accounts pursue ex post precision. The objective is to ensure that the price paid accurately reflects the company’s financial position at the moment control is transferred.

Professional analyses show that this mechanism remains widely used in non-sponsor transactions, complex carve-outs, and situations involving significant working capital volatility.

Definition and General Principle

Completion Accounts involve adjusting the price after closing based on accounts specifically prepared as of the effective transfer date.

The acquisition agreement generally sets:

A negotiated Enterprise Value
A target level of net debt
A target level of working capital

At closing, a provisional price is paid based on estimates. Within a defined period (typically 30 to 90 days), closing accounts are prepared to determine actual net debt and working capital at completion. The difference between actual and target levels results in a price adjustment.

The mechanism therefore aims to align the price paid with the company’s effective financial position at transfer.

Conditions for Application

Completion Accounts are particularly appropriate where financial conditions may significantly evolve between signing and closing.

This is notably the case:

Where working capital is highly seasonal
Where the company is undertaking significant investments
Where a carve-out involves complex internal adjustments
Where historical accounts do not provide sufficient reliability to fix the price confidently

The mechanism is also favored where the buyer seeks maximum protection against variations in cash or indebtedness prior to control transfer.

Contractual Architecture and Associated Mechanisms

Completion Accounts require precise contractual structuring.

The acquisition agreement must define in detail:

Calculation methodologies for net debt and working capital
Applicable accounting standards
Accounting principles to be applied
Deadlines for preparation and review
Dispute resolution procedures

In case of disagreement regarding the completion accounts, an independent expert is frequently appointed to resolve disputed items.

Financially, the mechanism is often complemented by a securing arrangement such as an escrow account held with a third party. A portion of the price is retained until the final determination of the purchase price.

This structure avoids requiring the seller to reimburse significant amounts post-closing, thereby limiting operational and relational tensions.

Advantages

The primary advantage of Completion Accounts lies in economic precision. The buyer pays for the actual financial position at transfer.

The mechanism also protects against opportunistic cash extraction or artificial working capital manipulation during the interim period.

In certain contexts, this precision builds sufficient trust to enable transactions that might otherwise fail.

Limitations and Points of Attention

Completion Accounts create temporary uncertainty regarding the final price. The seller lacks immediate visibility on the ultimate proceeds.

The mechanism may also generate complex technical discussions — or even disputes — regarding accounting classification. Disagreements concerning working capital definitions or debt classification are among the most common sources of post-closing litigation.

Finally, post-closing adjustment extends the transactional relationship beyond closing, potentially slowing integration.

Comparative Table: Locked-box vs Completion Accounts

The two mechanisms reflect distinct transactional philosophies. The table below summarizes their key structural differences.

Summary of the structural differences between the Locked-box and Completion Accounts mechanisms in M&A.

Practical Case and Hectelion’s Observations

In transactional practice, the choice between Locked-box and Completion Accounts is not ideological but strategic. Experience shows that process structure and financial transparency largely determine the appropriate mechanism.

Consider a Swiss SME valued at an EBITDA multiple, with an Enterprise Value of CHF 18 million. Annual accounts are audited, financial structure is stable, and working capital is not highly seasonal. In a competitive process involving several financial buyers, the seller’s priority is price certainty and closing fluidity.

In such circumstances, Hectelion favors a Locked-box structure where possible. Fixing the price at an earlier date avoids post-closing discussions, enhances comparability between bidders, and reduces subsequent tension. Leakage is strictly defined, and a ticking fee may be included where appropriate.

Conversely, where working capital is highly seasonal or financial conditions evolve significantly between signing and closing, freezing the price on historical accounts may expose the buyer to disproportionate risk. Completion Accounts may then be more appropriate.

However, post-closing adjustments frequently constitute a primary source of tension. Divergences in accounting interpretation may lead to prolonged discussions or even expert determination. Even when contractually anticipated, significant post-closing reimbursement obligations may strain relationships.

For this reason, when Completion Accounts are implemented, Hectelion systematically recommends the use of an escrow or third-party blocked account to secure potential adjustments. Retaining part of the price protects the buyer while avoiding destabilizing repayment obligations for the seller.

The approach is pragmatic: Locked-box is preferred where financial transparency and operational stability allow. Where these conditions are absent, Completion Accounts remain appropriate — provided adequate escrow safeguards are in place.

The objective is simple: secure the economic balance of the transaction while preserving closing fluidity and post-closing relationships.

Numerical Illustration: Locked-box Application

Enterprise Value: CHF 20 million
Net debt at 31.12.N (Locked-box date): CHF 4 million

Equity Value: CHF 16 million

Signing occurs in March N+1; closing in June N+1.

Between 1 January and closing:

CHF 1.2 million of cash flow is generated
No dividends are distributed
No shareholder loans are repaid
No unauthorized leakage occurs

Under a Locked-box structure, the price remains CHF 16 million. The buyer economically benefits from post-reference date cash flows, unless a ticking fee applies. No post-closing adjustment occurs.

The seller receives the full price at closing (subject to standard warranty mechanisms), and the transaction is fully crystallized.

Numerical Illustration: Completion Accounts Application

Enterprise Value: CHF 20 million
Target net debt: CHF 4 million
Estimated Equity Value: CHF 16 million

At closing:

CHF 15.5 million is paid to the seller
CHF 0.5 million is placed in escrow

Within 60 days, closing accounts are prepared:

Actual net debt: CHF 5 million
Working capital exceeds target by CHF 0.3 million

Total price adjustment: –CHF 1.3 million

Mechanism execution:

CHF 0.5 million is drawn from escrow
CHF 0.8 million must be reimbursed by the seller

Although contractually foreseen, such reimbursement may generate technical discussions and relational tension.

CEO Statement

“In our daily M&A practice, we observe that closing mechanisms are too often perceived as a minor contractual detail. In reality, they represent one of the most sensitive equilibrium points of a transaction.

A price may be perfectly negotiated on paper, supported by rigorous financial analysis. Yet if the closing mechanism is poorly calibrated, it may destabilize the deal, create post-closing tension, and even impair buyer-seller relationships from the outset.

At Hectelion, we favor Locked-box structures where appropriate. Price certainty enhances process fluidity and significantly reduces litigation risk. However, Locked-box is not universal. In situations of working capital volatility, carve-outs, or accounting uncertainty, Completion Accounts are justified. In such cases, rigorous structuring and escrow safeguards are essential.

Closing should mark the beginning of a new phase for the company, not the opening of a financial dispute. The mechanism must strike a balance between legal certainty, economic fairness, and operational pragmatism.

The choice between Locked-box and Completion Accounts is not ideological. It is contextual. Our role is to identify the appropriate equilibrium.”

Conclusion: Closing as a Tool of Transactional Balance

Choosing a closing mechanism is neither a technical formality nor a mere contractual custom. It is a structural decision regarding how the negotiated price will be executed and how economic risk will be allocated.

Locked-box prioritizes certainty and simplicity, crystallizing the price and facilitating integration. Completion Accounts prioritize precision and buyer protection, though at the cost of temporary uncertainty.

Neither mechanism is inherently superior. Their relevance depends on transaction context, financial quality, party profiles, and negotiation dynamics.

Ultimately, the closing mechanism is not a secondary consideration. It is one of the essential levers ensuring that negotiated value translates into balanced and secure economic reality at transfer.