Recent merger control developments in Latin America: Argentina and Mexico

Latin America has undergone significant transformation in the field of merger control over the past decade. Competition regulators across the region have grown markedly in sophistication, institutional capacity, and enforcement efficacy, evolving into regimes that increasingly reflect international best practices. Against this backdrop, mandatory pre-closing merger review has become the norm rather than the exception.

This post examines recent significant developments in two jurisdictions: Argentina and Mexico. Both countries have implemented, or are in the process of implementing, material changes to their merger control regimes that carry practical implications for businesses active in, or acquiring assets in, Latin America. In Argentina, the focus is on the long-anticipated shift from post-closing to pre-closing notification, which will take effect in November 2026. In Mexico, key developments include the establishment of a new merger control authority, a reduction in notification thresholds, and the introduction of a new tiered filing fee structure.

Clients with exposure to either jurisdiction should carefully consider whether these changes affect the timing, cost, or complexity of their transaction planning.

Argentina

Merger control was introduced in Argentina in 1999 under Law 25,156, one of the first pieces of antitrust legislation in the region. The Competition Act (Ley de Competencia or “LdC”) was subsequently enacted in 2018, establishing a new merger control regime under which the notifying parties could not finalise the transaction until they had obtained prior authorisation from the competition regulator.

The new pre-closing regime would commence and replace the current post-closing regime (in which filings are made up to seven days after the transaction closing) one year after the start of operations of a new regulatory entity known as the National Competition Authority (Autoridad Nacional de Competencia or “ANC”).

On 17 November 2025, the ANC, created through Decree 810/2025, initiated its operations, triggering the statutory one-year countdown to the new pre-closing regime.

The new merger control regime in Argentina

Pursuant to the one-year countdown provided in the LdC, the pre-closing regime will enter into force on 17 November 2026.

Additionally, in January 2025, new changes were incorporated into the regime, including changes to their simplified procedure, known as “Prosum,” and clarifications regarding which types of transactions may be exempted from merger notification.

a. What types of transactions are covered?

According to Article 7 of the LdC, transactions that result in a change of control of an undertaking must be notified prior to closing. Such transactions include the following:

1. Mergers;
2. Bulk transfers;
3. The acquisition of property or any rights in respect of shares or equity interests, or debt securities which confer any right to be converted into shares or equity interests or to exert any influence over the internal decision-making process of the entity that issues them, when such acquisition grants the acquirer control of, or substantial influence over, the company;
4. Any other agreement or act that may, in fact or in law, transfer the assets of an undertaking to a person or economic group, or confer on them decisive influence over the day-to-day or extraordinary management decisions of an undertaking;
5. Any of the acts referred to in subparagraph (iii) above which involve the acquisition of substantial influence over the competitive strategy of an undertaking.

b. What are the applicable notification thresholds?

On and after 17 November 2026, pre-closing notification will be mandatory, provided that the threshold established in Article 9 of the LdC is met:

This combined threshold considers the turnover of the target, acquirer, and its business group, but excludes the turnover of the seller.

Notwithstanding the above, a de minimis exemption² applies, and a transaction would not need to be notified³, when the sum of the value of the transaction and the value of the assets located in Argentina that are acquired do not exceed the equivalent of twenty million mobile units (approx. USD 19.6M).

For this exemption to apply, the parties must not have carried out any other transaction within the same market with a combined value of twenty million mobile units (approx. USD 19.6M) in Argentina in the last 12 months, or with a combined value of sixty million mobile units (approx. USD 59.6M) in the last 36 months.

c. What happens if the parties fail to notify a transaction?

Under the pre-closing regime, failure to notify a transaction may give rise to daily fines of up to 0.1% of the total business volume of the offending party’s business group, accruing from the date of closing until approval is obtained. If this basis for calculation cannot be determined, a fine of up to 750,000 mobile units (approx. USD 738,000⁴) may be applied (Article 55(d) of the LdC).

d. Are foreign-to-foreign transactions covered?

Yes, foreign-to-foreign transactions that meet the notification threshold will be subject to mandatory pre-closing notification. However, exemptions apply where local effects are absent, including:

• Acquisitions of a single company by a single foreign company that does not already hold assets (excluding those for residential purposes) or shares in other companies in Argentina, and whose exports to Argentina have not been significant, regular or frequent over the last thirty-six months (assessed on a case-by-case basis); and
• Acquisitions of companies that have not carried out any activity in Argentina during the last 12 months, unless the principal activities of the target company and the acquiring company are identical.

e. Is there a pre-notification phase, and who are the notifying parties?

According to Article 8 of the Regulation on the Notification of Concentrations (Reglamento para la Notificación de Operaciones de Concentración Económica), pre-notification is a voluntary procedure where the parties can contact the ANC prior to notification and on a confidential basis to raise any questions regarding the information to submit or any procedural aspect. The ANC is not bound by pre-notification discussions, which serves informational purposes only.

f. Is there a fast-track procedure available?

A simplified procedure, Prosum, is available for transactions unlikely to raise material competition concerns, including conglomerate concentrations, shifts from joint to sole control by an existing shareholder, and horizontal or vertical concentrations falling below prescribed market shares and HHI thresholds (Article 3 of Annex I of Provision 156/2024).

This procedure expressly excludes transactions where the post-merger HHI exceeds 2,500 and where the transaction may result in the merging parties gaining significant market power. It additionally contains several exclusion criteria that are framed in general terms, which affords the ANC a broader discretion to undertake a case-by-case assessment of whether summary proceedings are appropriate. Further, opposition from other Argentine regulatory agencies may independently preclude use of the Prosum, even where the transaction would otherwise appear to qualify (Article 4 of Annex I of Provision 156/2024).

In Prosum proceedings, once the parties submit form F0 the ANC has up to 45 business days to evaluate whether the transaction qualifies for the summary procedure, assess whether additional information is needed to complete form F0, and, where no significant competition concerns are identified, issue clearance (Article 14 of the LdC and Article 9 of the Regulation on the Notification of Concentrations). However, if the transaction is deemed to not qualify for the Prosum proceeding, parties must submit form F1 to initiate the ordinary procedure.

The Prosum procedure tends to result in faster clearance than the ordinary procedure, notwithstanding that the statutory review deadlines are identical. This is primarily attributable to the less extensive notification form required (form F0 as opposed to form F1), which reduces the administrative burden on notifying parties at the outset and limits the scope of substantive analysis required of the ANC.

g. What are the Phase 1 and Phase 2 review periods?

The 45-business-day review deadline for Prosum proceedings also applies for the ordinary procedure. However, this review period only commences once the notifying parties have submitted the ordinary notification form (form F1) together with form F0. In the event that the ANC requests parties to submit form F2 (which seeks further information regarding relevant markets), the parties will have an additional 30 business days to make this submission, with the review deadline suspending until the form is submitted.

If the ANC considers that the notified transaction has the potential to restrict or distort competition, it may extend the review period by up to an additional 120 business days once a preliminary statement of objections is issued. This review period commences once the parties have responded to the ANC’s objections.

It is important to note that, historically, even simple transactions could take up to 6 months to obtain approval. This is due to the fact that the ANC may determine that the notification is incomplete, and additional information is required, before the review period begins. Any further requests for information from the ANC during the review period will also result in the suspension of the statutory deadlines. After conducting review, the ANC may clear the transaction, approve it subject to remedies imposed by the competition authority or prohibit the transaction. Where the review period elapses without a decision, the transaction shall be deemed tacitly authorised.

That said, it remains to be seen how the new competition authority will manage its review process, given the importance of predictability and clearly defined procedural deadlines, particularly in the context of global mergers.

h. Can the parties appeal a decision by the ANC?

Where the ANC prohibits a transaction or imposes remedies, the decision may be appealed within 15 days of the notification of the ANC’s decision. The appeal will be heard and decided by the specialized competition chamber of the National Court of Appeals in Civil and Commercial Federal Matters.

i. Transition period

Law 27,442 establishes a transition period from 17 November 2025 to 17 November 2026, during which the regime remains formally in the post-closing phase, and where a transaction must be notified one week after closing.

Parties whose transactions are projected to close around November 2026 should carefully consider whether a pre-closing notification filing is advisable, so as to avoid the risk of closing a transaction after the new regime takes effect and thereby triggering potential gun-jumping.

This is particularly relevant given that there is currently no carve-out mechanism that would allow Argentina to be excluded from a global closing without triggering regulatory objections. 

Mexico

Key developments in 2025

On 17 October 2025, the new competition regulator in Mexico, the National Antitrust Commission (Comisión Nacional Antimonopolio “CNA”), began operating, replacing the former Federal Economic Competition Commission and the Federal Telecommunications Institute as the bodies responsible for reviewing merger control filings.

While the new competition agency retains complete technical and operational autonomy in exercising its decision-making powers, it has transitioned from a constitutionally autonomous entity to a decentralized entity under the Economy Secretary. Under this new structure, the agency’s budget is contingent on the income it is able to generate, a point of direct relevance given the introduction of the new filing fees, as discussed further below.

In addition to these institutional changes, the Federal Economic Competition Law (Ley Federal de Competencia Económica or “LFCE”) was amended to reduce the statutory merger control review period from 100 to 50 business days, comprising an initial period of 30 days and 20 additional days for more complex cases. This reduction will be of particular benefit to non-problematic transactions, as it will shorten the review period.

It should be noted, however, that the review period only commences once the CNA determines that the notification is complete, which affords the agency some flexibility in managing its caseload. Additionally, the period during which the CNA may investigate non-notified transactions was extended from one to three years.

Notwithstanding the above, the two main developments for 2026 are the new thresholds that trigger mandatory merger notification and the introduction of new filing fees.

New thresholds

Among the most significant changes is a reduction in the notification thresholds, which is expected to bring a greater number of transactions within the CNA's mandatory filing regime.

The table below sets out the different types of thresholds that may trigger mandatory pre-closing notification before the CNA (Article 86 LFCE):

The LFCE amendments have also eliminated the exemption previously available to foreign-to-foreign transactions, meaning that deals involving target companies with no physical presence in Mexico (whether by way of subsidiaries or assets) may now trigger a mandatory filing where the target generates revenues in Mexico.

New filing fees

A further significant development in December 2025 was the introduction of updated filing fees, replacing the former flat fee (approx. USD 13.000) with a tiered structure based on the transaction’s maximum estimated value in Mexico (“VME”). The purpose of this change is to help the CNA finance its operations.

Prior to filing, the parties must declare and justify the applicable VME and, before closing, provide all information necessary to determine its final value, on the basis that the criteria yielding the highest fee shall apply.

The VME is determined by reference to the highest value across the three threshold values described above and as established in Article 86 of the LFCE.

Depending on the applicable VME tier, this development represents a fee increase of between 250% and 2,230% compared to the previous flat fee, which parties and their advisers will need to factor carefully into transaction planning.

Conclusion

These developments in Argentina and Mexico form part of a broader shift across Latin America towards more demanding and procedurally complex merger control regimes, with significant practical consequences for businesses operating in or acquiring assets in the region.

In Argentina, the transition to mandatory pre-closing notification from November 2026 represents a fundamental change in transaction timing. While the substantive scope of the regime, including its thresholds, notifiable transaction types, and review standards, remains materially unchanged, the procedural implications will have direct consequences for how global transactions are structured and timed.

Parties will need to build Argentine clearance into their global signing-to-closing timelines, account for the absence of any carve-out mechanism allowing Argentina to be excluded from a global closing, and engage early with the ANC given the uncertainty surrounding how the newly established authority will manage its review processes in practice. Transactions projected to close in or around November 2026 warrant particularly careful consideration, given the material risk of inadvertently closing a transaction prior to approval and incurring gun-jumping exposure under the incoming regime.

In Mexico, the combination of lower notification thresholds, coupled with the elimination of the foreign-to-foreign exemption, will bring a materially larger number of transactions within the CNA's mandatory filing regime, including deals involving targets with no physical presence in Mexico but with Mexican-sourced revenues. The introduction of a tiered filing fee structure, representing increases of up to 2,230% relative to the prior flat fee, adds a meaningful cost dimension that parties must factor into transaction economics at an early stage.

The current mobile unit is valued at ARS 1,450.05 from 17 January 2026, while the currency rate is calculated using the daily average sell rate reported by the Banco de la Nación Argentina on the last working day of 2025, i.e. ARS 1480 per USD.

Considering Argentina’s exchange rate fluctuations, it is important to verify the amounts set out for the de minimis exemption. These values were calculated according to the exchange rate in effect as of 30 June 2026 published by the Banco de la Nación Argentina, i.e. ARS 1473 per USD.

The acquisition of bonds, debentures, shares without voting rights, or any other debt security of the entity is also exempted from notification, as are transactions where the acquiring company previously held 50% or more of the shares of the target company and no change of control occurs.

According to the exchange rate in effect as of 30 June 2026 published by the Banco de la Nación Argentina, i.e. ARS 1473 per USD.

The Unidad de Medida y Actualización or UMA is the official economic index used to calculate fines, taxes or government fees set out annually by the National Institute of Statistics and Geography. The notification thresholds included a UMA value of MXN 117.31, effective from 1 February 2026.

The USD value is an approximation as the VME is based on the latest daily settlement rate published by the Banco de México (30 June 2026). The currency considers a conversion of MXN 17.5 per USD.