Fast or slow lane? Merger control review periods influence deal timelines

In 2025, the average time to get an unconditional clearance at phase 1—the most likely outcome of a merger review—dropped to 18 working days across the jurisdictions surveyed.  

Conditional phase 1 cases also saw slightly quicker review periods on average: 66 working days compared to 69 in 2024. 

It was a different story at phase 2.  

The duration of in-depth investigations continues to vary widely from jurisdiction to jurisdiction and can be unpredictable. In 2025, some authorities took over a year to reach a final decision, even in cases that were ultimately cleared unconditionally. 

UK picks up the pace  

Pace is the first “P” in the Competition and Markets Authority (CMA)’s new “4Ps” framework, which it is applying across its functions to drive growth, investment, and business confidence.  

In merger control, this has translated into a non-binding 25 working-day target for completing reviews of straightforward phase 1 cases, significantly shorter than the statutory deadline of 40 working days.  

Since its introduction in June, the CMA has met this target in all but one of its unconditional phase 1 clearances.  

The authority has also taken steps to slash the pre-notification period, establishing a new KPI to complete this phase within 40 working days (down from an average of 65).  

These targets are ambitious, and the CMA notes that they require the cooperation of merging parties to be achievable. Overall, they should amount to a major streamlining (or at least front-loading) of the UK merger control process for no-issues cases.  

U.S. early termination is back  

Under Trump 2.0 the U.S. antitrust agencies have reinstated the early termination procedure, which cuts short the initial 30-day waiting period for transactions raising no concerns.  

In theory, this is good for merging parties.  

And, looking holistically at the merger control timeline, while any benefits achieved by early termination may have been cancelled out by the additional time needed to prepare the new Hart-Scott-Rodino filing form, a court ruling that throws out the overhaul could mean further timing benefits for merging parties (see Fewer roadblocks for M&A: Politics play into lighter touch merger control enforcement). 

In Canada, too, additional information requirements relating to market shares and concentration metrics have had an impact on end-to-end review periods. 

Pulling and refiling (mostly) yields results  

Withdrawing merger control filings during the initial review and then resubmitting later remains a popular tactic, particularly in the U.S. We have also seen examples in the EU and Germany.  

It can be useful if an authority has initial concerns about a deal, but a tight phase 1 review period does not allow it enough time to get comfortable that those concerns do not warrant an in-depth review or to assess proposed remedies. It can also help give an authority more time to test market data. 

In most cases, parties employing this strategy managed to avoid an in-depth investigation.  

However, this was not always the outcome last year, highlighting that the approach can be risky, especially where antitrust issues are expected to be extensive or complex.  

Suspensions disrupt timelines  

Many antitrust authorities have “stop-the-clock” powers, allowing them to pause (or even restart from the beginning) review periods. These are often used during in-depth reviews when merging parties have not responded to information requests by a specified deadline.  

Sometimes these suspensions can last many months.  

In China, the State Administration for Market Regulation stopped the clock for around 17 months—its longest ever suspension—in the in-depth review of ANA Holdings/Nippon Cargo. Other deals were also suspended. 

In Europe, the European Commission (EC) stopped the clock in each EU phase 2 review opened or concluded in 2025. Over a dozen reviews were paused in France, where suspensions can in some cases stretch upwards of 100 working days.  

Long-stop dates feel the strain 

Lengthy merger control (and other regulatory) processes can put significant pressure on deal timetables.  

In some cases, this may force parties to extend the originally agreed long-stop date.  

We saw Prosus extend the acceptance period of its public offer for Just Eat, and Anglo American and MMG agree to push the long-stop date for their tie-up by seven months, in both cases due to the EU merger control process.  

Absent mutual agreement to extend long-stop dates, such antitrust intervention may ultimately result in deals falling over. In two of the three mergers abandoned in the U.S. last year, the acquirer announced it would not proceed with the transaction because the agency’s review had not completed by the deal deadline.