杠杆收购 · 2026-02-11

Antitrust Due Diligence in LBOs: Market Share Calculation, Competitive Impact Assessment, and Remedies

The Competition Ordinance (Cap. 619) came into full effect in Hong Kong on 14 December 2015, but it is the Competition Commission’s escalating enforcement activity in 2024-2025 that has fundamentally shifted the risk calculus for leveraged buyouts (LBOs) targeting Hong Kong-listed or Hong Kong-incorporated entities. The Commission’s first successful merger control prosecution under the Ordinance, Competition Commission v. W. Hing Construction Co Ltd & Others [2024] HKCT 1, resulted in a record HKD 2.15 million fine for anti-competitive agreements in the construction sector, serving as a stark warning that the era of regulatory forbearance has ended. For PE sponsors structuring LBOs, the traditional focus on financial due diligence—EBITDA multiples, debt service coverage ratios, and exit valuations—is no longer sufficient. A failure to conduct rigorous antitrust due diligence, specifically regarding market share calculation and the competitive impact of portfolio company consolidation, can result in blocked transactions, forced divestitures, or exposure to treble damages under the Ordinance. This article provides a technical framework for calculating market share within the context of an LBO, assessing the competitive impact of the acquisition, and structuring remedies to secure clearance from the Competition Commission.

Market share calculation in an LBO is distinct from a standard public M&A transaction because the deal structure—specifically the use of a newly formed special purpose vehicle (SPV) as the acquisition entity—creates a unique analytical challenge for the Competition Commission. The Commission’s Merger Guidelines (2024 edition) stipulate that the relevant undertaking for market share assessment is the “acquiring undertaking,” which in an LBO is typically the SPV, but the economic substance is the combined entity post-acquisition. This requires a forward-looking analysis that consolidates the market positions of the target company and any existing portfolio companies of the PE sponsor operating in the same or adjacent product markets.

Defining the Relevant Product and Geographic Market

The first step in market share calculation is the precise delineation of the relevant market under the Competition Ordinance (Cap. 619), Section 2, which adopts the “small but significant and non-transitory increase in price” (SSNIP) test. For an LBO targeting a Hong Kong-listed company, the product market is defined by demand-side substitutability—whether customers would switch to alternative products in response to a 5-10% price increase. The geographic market, for most Hong Kong-focused transactions, is the Hong Kong Special Administrative Region, unless the target’s operations extend into the Greater Bay Area, in which case the Commission may consider a broader geographic scope under the Guidelines on the First Conduct Rule and Second Conduct Rule (2024). For example, in an LBO of a Hong Kong-based logistics provider, the relevant product market might be “time-definite domestic delivery services,” and the geographic market would be Hong Kong, excluding cross-border services unless the target has a material presence in Shenzhen.

Market share is calculated using two primary metrics: revenue-based share (turnover) and volume-based share (units sold or capacity). The Commission’s Merger Guidelines (2024) state that revenue-based share is the default metric for assessing dominance under Section 21 of the Ordinance, but volume-based share is used when revenue data is distorted by pricing anomalies or bundling practices. For an LBO target, the calculation must include the target’s standalone revenue and the revenue of any portfolio companies controlled by the PE sponsor that operate in the same relevant market. The Competition Commission v. W. Hing Construction Co Ltd & Others case established that the Commission will look through corporate structures to identify “economic units”—meaning that a PE sponsor cannot avoid market share aggregation by holding portfolio companies through separate fund vehicles. The practical implication is that a PE sponsor with three portfolio companies in the Hong Kong construction sector, each with a 5% market share, would be treated as a single undertaking with a 15% market share, triggering the 25% market share threshold for the application of the Second Conduct Rule (abuse of substantial market power) under Section 21.

The Aggregation Problem in Multi-Fund Structures

The aggregation of market share across multiple PE funds is the most technically complex aspect of antitrust due diligence in LBOs. Under the Competition Ordinance (Cap. 619), Section 8, an “undertaking” includes any entity “engaged in economic activity,” and the Commission’s Guidelines on the Definitions of “Undertaking” and “Economic Activity” (2024) clarify that control—defined as the ability to exercise decisive influence—triggers aggregation. For a PE sponsor managing multiple funds (e.g., Fund I, Fund II, and Fund III), each fund is a separate legal entity, but the sponsor’s management company exerts decisive influence over all portfolio companies. The Merger Guidelines (2024) state that the Commission will assess whether the sponsor has “de facto control” over the portfolio companies, considering factors such as board representation, veto rights over strategic decisions, and the appointment of key management. In practice, this means that a sponsor with a 30% equity stake and board control in a portfolio company must aggregate that company’s market share with the target’s market share, even if the sponsor holds the stake through a separate fund. The Competition Commission v. W. Hing Construction Co Ltd & Others judgment confirmed that the Commission will disregard legal formalities and focus on economic reality, making it imperative for sponsors to map all portfolio companies in the target’s product and geographic markets before filing a merger notification.

Once market share is calculated, the next step is the competitive impact assessment, which determines whether the transaction raises concerns under the First Conduct Rule (anti-competitive agreements) or the Second Conduct Rule (abuse of substantial market power). The Competition Ordinance (Cap. 619) does not have a mandatory merger control regime for non-telecommunications mergers, meaning that most LBOs are not subject to pre-merger notification. However, the Commission can investigate a completed transaction under Section 24 if it raises competition concerns, and the Merger Guidelines (2024) identify three categories of transactions that are “likely to be investigated”: those resulting in a market share exceeding 40%, those involving a market leader with a share exceeding 25% and a target with a share exceeding 10%, and those that eliminate a “material competitive constraint.”

The Unilateral Effects Analysis

Unilateral effects arise when the merged entity has the ability to unilaterally raise prices or reduce output without coordination with competitors. The Commission’s Guidelines on the First Conduct Rule and Second Conduct Rule (2024) specify that unilateral effects are assessed using the Herfindahl-Hirschman Index (HHI) and the post-merger market share of the combined entity. For an LBO, the analysis must consider the target’s pre-merger pricing behavior, capacity constraints, and the likelihood of entry by new competitors. The Competition Commission v. W. Hing Construction Co Ltd & Others case provides a practical example: the Commission found that the coordinated behaviour among construction companies in the public works tender market constituted an anti-competitive agreement under the First Conduct Rule, and the market shares of the participants (ranging from 8% to 15%) were sufficient to demonstrate a “significant adverse effect on competition” under Section 24. For an LBO, the sponsor must assess whether the target’s market share, combined with the sponsor’s existing portfolio companies, creates a post-merger entity with a market share exceeding 40%, which triggers a rebuttable presumption of substantial market power under Section 21.

The Coordinated Effects Analysis

Coordinated effects are more subtle but equally dangerous in concentrated markets. The Commission’s Merger Guidelines (2024) state that a transaction may substantially lessen competition if it increases the likelihood of coordinated behaviour among remaining market participants. For an LBO, this is particularly relevant in markets with high entry barriers (e.g., regulated industries, infrastructure-intensive sectors) and a small number of competitors (oligopolistic markets). The Competition Commission v. W. Hing Construction Co Ltd & Others case demonstrated that even in a market with 15-20 competitors, the Commission will investigate if the transaction eliminates a “maverick” competitor—a firm that historically undercuts pricing or refuses to participate in coordination. The sponsor must identify whether the target is a maverick; if so, the transaction may be blocked even if the combined market share is below 40%. The practical implication is that the competitive impact assessment must include a qualitative analysis of the target’s pricing history, participation in trade associations, and any past investigations by the Commission.

The Vertical Effects and Conglomerate Effects

Vertical effects arise when the LBO combines a supplier and a customer, giving the merged entity the ability to foreclose rivals from upstream or downstream markets. The Commission’s Guidelines on the First Conduct Rule and Second Conduct Rule (2024) specify that vertical mergers are assessed under the “input foreclosure” and “customer foreclosure” theories of harm. For an LBO, this is relevant when the target supplies a key input to the sponsor’s existing portfolio companies, or when the target is a major customer of the sponsor’s portfolio companies. The Competition Commission v. W. Hing Construction Co Ltd & Others judgment did not involve vertical effects, but the Commission’s Merger Guidelines (2024) cite the European Commission’s GE/Instrumentarium case as a precedent for assessing conglomerate effects—where the merged entity has the ability to leverage market power from one market into another through bundling or tying. For a PE sponsor, this means that an LBO of a Hong Kong-listed software company that provides complementary products to the sponsor’s existing hardware portfolio company may trigger a conglomerate effects investigation, even if the combined market share in each individual market is below 40%.

Structuring Remedies to Secure Clearance

If the competitive impact assessment identifies potential concerns, the sponsor must structure remedies to secure clearance from the Competition Commission. The Competition Ordinance (Cap. 619), Section 60, empowers the Commission to accept commitments from parties to address competition concerns, and the Merger Guidelines (2024) outline two categories of remedies: structural remedies (divestitures) and behavioural remedies (conduct commitments). For LBOs, structural remedies are preferred by the Commission because they permanently remove the competitive concern, while behavioural remedies require ongoing monitoring and are viewed as less effective.

Structural Remedies: Divestiture of Overlapping Assets

The most common structural remedy is the divestiture of overlapping assets to eliminate the market share aggregation issue. The Commission’s Guidelines on the Use of Remedies in Competition Cases (2024) specify that the divested assets must be “viable and capable of being operated independently by a suitable purchaser.” For an LBO, this means that the sponsor must identify a carve-out of the target’s business lines that overlap with the sponsor’s existing portfolio companies, and then find a buyer for those assets. The Competition Commission v. W. Hing Construction Co Ltd & Others case did not involve a divestiture remedy, but the Commission’s Merger Guidelines (2024) cite the UK Competition and Markets Authority’s Tesco/Booker case as a precedent for requiring divestiture of stores in local markets where the combined market share exceeded 40%. For a Hong Kong LBO, the sponsor must identify the specific product and geographic markets where the combined market share exceeds 25% (the threshold for substantial market power under Section 21) and prepare a divestiture plan that can be implemented within 6-12 months of the transaction closing.

Behavioural Remedies: Firewalls, Non-Discrimination, and Access Commitments

Behavioural remedies are less common but may be accepted by the Commission in cases where structural remedies are impractical or disproportionate. The Competition Commission’s Enforcement Policy (2024) states that behavioural remedies will only be accepted if they are “clear, specific, and capable of being effectively monitored.” For an LBO, typical behavioural remedies include: (i) a firewall commitment preventing the exchange of competitively sensitive information between the target and the sponsor’s existing portfolio companies; (ii) a non-discrimination commitment requiring the merged entity to supply inputs to competitors on the same terms as to its own downstream operations; and (iii) an access commitment requiring the merged entity to grant competitors access to essential facilities or intellectual property. The Competition Commission v. W. Hing Construction Co Ltd & Others case did not involve behavioural remedies, but the Commission’s Merger Guidelines (2024) cite the Hong Kong Competition Commission’s own MTR Corporation/Octopus Holdings case (2016) as a precedent for accepting a behavioural remedy—specifically, a commitment by MTR to ensure that Octopus’s payment system would remain open to competitors. For a PE sponsor, behavioural remedies are most appropriate in LBOs of regulated industries (e.g., utilities, transportation) where the target’s market share is between 25% and 40% and the competitive concern is limited to a specific input or customer group.

The Role of the Competition Commission’s Informal Guidance Process

Before committing to a remedy, sponsors should consider the Competition Commission’s informal guidance process under the Guidelines on the Commission’s Approach to Mergers and Acquisitions (2024). The Commission offers a confidential, non-binding opinion on whether a proposed transaction raises competition concerns, and this opinion can be obtained before the transaction is announced. The Competition Commission v. W. Hing Construction Co Ltd & Others case highlights the cost of failing to seek guidance: the parties were fined HKD 2.15 million and subjected to a public investigation that damaged their reputations. For an LBO, the informal guidance process is particularly valuable because it allows the sponsor to test the Commission’s view on market share aggregation and competitive impact without triggering a formal investigation. The Commission’s Merger Guidelines (2024) state that the informal guidance process takes 6-8 weeks, meaning that the sponsor must factor this timeline into the LBO’s financing and regulatory approval milestones. The sponsor should prepare a detailed market share calculation, a competitive impact assessment, and a proposed remedy framework before approaching the Commission.

Key Takeaways for PE Sponsors and Their Advisors

The integration of antitrust due diligence into the LBO process is no longer optional; it is a regulatory necessity driven by the Competition Commission’s escalating enforcement activity and the Competition Commission v. W. Hing Construction Co Ltd & Others precedent. The following actionable takeaways are designed for PE sponsors, in-house legal teams, and external counsel structuring LBOs in Hong Kong.

Map all portfolio companies in the target’s relevant product and geographic markets before signing any exclusivity agreement, using the Competition Commission’s Merger Guidelines (2024) definition of “economic unit” to determine whether market share aggregation is required across multi-fund structures.
Calculate market share using both revenue-based and volume-based metrics, and prepare a sensitivity analysis that tests the impact of a 5% and 10% price increase under the SSNIP test, as required by the Competition Ordinance (Cap. 619), Section 2, and the Commission’s Guidelines on the Definitions of “Undertaking” and “Economic Activity” (2024).
Seek informal guidance from the Competition Commission at least 8 weeks before the expected transaction announcement, using the confidential process under the Guidelines on the Commission’s Approach to Mergers and Acquisitions (2024), to test the Commission’s view on market share aggregation and competitive impact.
Prepare a structural remedy plan (divestiture of overlapping assets) as the default option, and only consider behavioural remedies (firewalls, non-discrimination commitments) if the Commission explicitly indicates that structural remedies are disproportionate, as per the Guidelines on the Use of Remedies in Competition Cases (2024).
Incorporate antitrust due diligence findings into the LBO financing structure, specifically the debt service coverage ratio and the exit valuation assumptions, because a blocked transaction or forced divestiture will materially impair the sponsor’s ability to service the acquisition debt and achieve the target IRR.