Canada’s sweeping overhaul of merger control, including the introduction of a structural presumption aligned with US practice, is beginning to stabilize after an adjustment period, with early evidence suggesting the tougher framework has not materially slowed routine deal reviews, a senior enforcement official said.
Canada’s sweeping overhaul of merger control, including the introduction of a structural presumption aligned with US practice, is beginning to stabilize after an adjustment period, with early evidence suggesting the tougher framework has not materially slowed routine deal reviews, a senior enforcement official said.“Our experience to date, 18 months since this change, I would say, has largely been positive,” said Anthony Durocher, acting senior deputy commissioner for mergers and monopolistic practices at Canada’s Competition Bureau.
“It's an adaptation, and there's been change management internally and expertly about how to navigate this. I think by and large, some of the early concerns about how this might slow down reviews for the more noncomplex transactions have not borne out when we looked at the data,” he said at a conference* in Washington.
The reforms, driven by concerns over affordability and weakening competitive intensity, came in three legislative waves that collectively reshaped core provisions of the Competition Act. Mergers were a central focus, with lawmakers explicitly aiming to strengthen frontline scrutiny, particularly in concentrated markets, Durocher said.
Among the most consequential changes are the elimination of the efficiencies defense, a revised remedy standard requiring authorities to restore or preserve competition to premerger levels, and an expanded role for nonprice factors such as labor. Amendments also extended the statute of limitations for non-notifiable transactions to three years and addressed gaps in notification requirements.
However, the most closely watched reform has been the adoption of a rebuttable structural presumption based on market concentration. Transactions that result in a change in the Herfindahl-Hirschman Index, or HHI, of more than 100 points, combined with either a post-merger HHI above 1,800 or market shares exceeding 30 percent are now presumed to be anticompetitive — thresholds that mirror the 2023 US merger guidelines.
Under this framework, the burden shifts to merging parties to demonstrate that the transaction will not substantially lessen or prevent competition.
Service standards, which differentiate between complex and noncomplex mergers, continue to be met, and overall clearance rates remain broadly unchanged, Durocher said. While there have been modest shifts in the composition of cases and slight increases in review timelines for simpler transactions, he said these variations fall within normal year-to-year fluctuations.
The experience to date has been characterized as an “adaptation phase,” involving both internal adjustments within the Competition Bureau and external recalibration by the bar.
— Guidance update in progress —
The bureau has completed a major public consultation on updated merger enforcement guidelines, with final revisions expected following a review of stakeholder submissions.
Durocher acknowledged that predictability remains a priority, particularly regarding how parties can rebut the new structural presumption.
Rebuttal evidence will continue to be assessed during the investigative stage, consistent with existing practice, he said. And merger review remains a holistic inquiry focused on whether a transaction is likely to create, maintain or enhance market power.
While market structure now carries greater weight, Durocher stressed that it will continue to balance structural indicators with evidence of competitive effects.
A “sliding scale” approach is expected to guide rebuttal analysis, he said: the further a transaction exceeds concentration thresholds, the stronger and more persuasive the evidence required to overcome the presumption.
*American Bar Association Antitrust Spring Meeting 2026. Washington, DC. March 25-27, 2026.
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