What Is an Antitrust Review?
An antitrust review — also called competition review or merger control — is the regulatory process through which government authorities evaluate whether a proposed M&A transaction would harm competition in the relevant market (Investopedia). Competition authorities can approve a deal unconditionally, approve it subject to conditions (remedies), or block it entirely.
Antitrust review is a critical gating item in M&A transactions. Failure to obtain regulatory clearance can kill a deal, and the conditions imposed by regulators can materially alter its economics and strategic rationale.
How Antitrust Review Works
Filing Thresholds
Most jurisdictions require merger notifications when the transaction meets defined thresholds, typically based on:
- Combined revenue — the merging parties’ aggregate revenue in the jurisdiction
- Transaction value — the deal size exceeds a defined amount
- Market share — the combined entity would exceed a market share threshold
- Asset value — the target’s assets in the jurisdiction exceed a threshold
Review Process
While specifics vary by jurisdiction, the general process follows a common pattern described by the International Competition Network:
- Pre-notification consultation — informal discussions with the authority about whether filing is required and what information will be needed
- Phase I review — an initial assessment (typically 25–45 days) to determine if the transaction raises competition concerns
- Phase II investigation — if Phase I identifies potential concerns, a deeper investigation (typically 90–120 additional days) involving detailed market analysis, third-party consultations, and economic modelling
- Decision — the authority clears the deal, clears it with conditions, or prohibits it
Possible Outcomes
- Unconditional clearance — the deal is approved as proposed
- Conditional clearance — the deal is approved subject to remedies, which may include divesting overlapping business units, licensing intellectual property, or behavioural commitments
- Prohibition — the deal is blocked; the parties may appeal, revise the deal, or abandon it
Key Jurisdictions
United States
The Federal Trade Commission (FTC) and Department of Justice (DOJ) administer the Hart-Scott-Rodino (HSR) Act, which requires pre-merger notification for transactions above defined thresholds. Review periods are 30 days (Phase I) with the possibility of a “second request” for additional information.
European Union
The European Commission reviews transactions meeting EU-wide revenue thresholds. Phase I takes 25 working days; Phase II takes up to 90 working days, extendable to 125.
Australia
The Australian Competition and Consumer Commission (ACCC) conducts merger reviews. Australia’s regime is currently transitioning to a mandatory notification system, strengthening enforcement.
Other Key Markets
China (SAMR), Japan (JFTC), South Korea (KFTC), India (CCI), and Singapore (CCCS) each have their own merger control regimes with varying thresholds, timelines, and enforcement approaches.
Impact on Deal Structuring
Antitrust risk fundamentally shapes how transactions are structured and documented:
- Conditions precedent — the sale and purchase agreement will include regulatory clearance as a condition to closing
- MAC clauses — may address the risk of regulatory changes during the review period
- Break-up fees — reverse break-up fees (payable by the buyer) may be negotiated to compensate the seller if the deal fails due to regulatory non-clearance
- Remedies planning — buyers may proactively offer divestitures or behavioural commitments to address anticipated concerns
- Exclusivity period — must be long enough to accommodate regulatory timelines
- Gun-jumping — parties must not integrate or coordinate competitively before clearance is obtained; violations carry significant fines
Antitrust Review in Asia Pacific
Antitrust review in Asia Pacific involves navigating multiple jurisdictions with different regimes, thresholds, and timelines. Cross-border transactions in the region frequently require filings in 3–5 or more countries simultaneously. China’s SAMR review can take 6–12 months for complex transactions and has become an increasingly significant gating item. Japan’s JFTC has streamlined its process but can still impose conditions on deals affecting concentrated domestic markets. Australia’s ACCC is known for thorough market testing. For dealmakers working across the region, see our overview of cross-border M&A in Asia and the APAC M&A guide. AI-native platforms like Amafi help advisors assess antitrust risk across multiple Asia Pacific jurisdictions and plan filing strategies for regional transactions.
Related Terms
Due Diligence
The comprehensive investigation and analysis process conducted by a prospective buyer to evaluate a target company's financial, legal, commercial, and operational profile before committing to an acquisition.
Exclusivity Period
A contractually agreed timeframe during an M&A process in which the seller commits to negotiating exclusively with one prospective buyer, typically preventing the solicitation of competing offers.
MAC Clause (Material Adverse Change)
A contractual provision in M&A agreements that allows a buyer to withdraw from a transaction if events occur between signing and closing that materially and adversely affect the target company's business, financial condition, or prospects.
Vendor Due Diligence
A due diligence investigation commissioned and paid for by the seller prior to a sale process, providing prospective buyers with an independent assessment of the target company.