UK Housebuilders Threatened With “Opt-Out” Competition Class Action

An opt-out collective action on behalf of homebuyers is being prepared for filing in Q1 2026 in relation to the UK housebuilding sector, with Mark McLaren seeking certification as class representative. The proposed claim follows an investigation by the Competition and Markets Authority (“CMA”) into suspected potentially anti-competitive conduct by seven major housebuilders in connection with the sale of new-build homes across Great Britain.

The CMA investigation was closed following the acceptance of binding, forward-looking commitments. Importantly, the CMA did not make any finding of infringement, and the commitments were offered and accepted without any admission of liability.

Background

The proceedings have not yet been filed. However, claimant-side announcements indicate that the proposed claim is intended to build on a CMA investigation opened in February 2024 into suspected breaches of the Chapter I prohibition of the Competition Act 1998, which prohibits agreements, decisions and concerted practices between undertakings which have as their object or effect the restriction, distortion or prevention of competition within the UK and which affect trade within the UK.

The investigation concerned seven of the largest housebuilders operating in Great Britain — Barratt Redrow, Bellway, Berkeley, Bloor, Persimmon, Taylor Wimpey and Vistry — which the CMA suspected may have engaged in exchanges of competitively sensitive information during the period from January 2022 to February 2024.

The collective proceedings are expected to seek damages on behalf of homebuyers on an opt-out basis, as is typical for claims of this nature.

Commitments vs infringement  

The CMA’s investigation did not culminate in a statement of objections or an infringement decision. Instead, it was closed following the acceptance of commitments under which the housebuilders agreed to cease the conduct giving rise to the CMA’s concerns and to implement certain forward-looking measures.

That distinction matters.

• An infringement decision involves a formal finding by a competition authority that competition law has been breached, following a full investigation. Such decisions can be relied upon as binding findings of liability in subsequent “follow-on” damages claims.

• By contrast, the acceptance of commitments brings an investigation to a close without any finding of infringement. Commitments are voluntarily offered, forward-looking in nature, and are accepted expressly without determining whether any unlawful conduct occurred. They do not establish liability and do not bind the court or tribunal in private damages proceedings. Any claim relying on commitments must therefore proceed as a stand-alone action, with infringement, causation and loss proved afresh.

Stand-alone rather than follow-on

The absence of an infringement decision means that any collective proceedings are likely to be framed as a stand-alone claim. The consequences are significant.

In a stand-alone action, the burden rests squarely on the claimant to establish every element of liability and loss from first principles. This includes defining the relevant markets, proving the existence of anti-competitive conduct, demonstrating its effects, constructing a credible counterfactual, and establishing causation and quantum of loss.

The fact that the housebuilders volunteered commitments does not give rise to any presumption of breach. Commitments are accepted without any finding or admission of infringement and do not shift the burden of proof in subsequent private damages claims.

Scope and defendants

At this stage, the contours of any eventual claim remain unclear. Public statements suggest that the claim may initially focus on the seven housebuilders that were subject to the CMA investigation. However, that position may evolve as the claim progresses towards filing.

It also remains to be seen whether the proposed class representative will seek to allege market-wide effects extending beyond the conduct examined by the CMA, potentially drawing in additional market participants based on alleged spill-over effects. Any such approach would materially increase complexity at the certification stage, sharpening issues around commonality, causation and proof of loss — particularly given the CMA’s express statement that its investigation did not extend to certain aspects of housebuilding activity.

Depending on how any claim is framed, limitation and temporal scope may also become contested issues, particularly given that the CMA’s investigation was confined to conduct alleged to have taken place during a relatively short, defined period between January 2022 and February 2024.

Certification

It may be tempting to assume that certification will follow as a matter of course because the proposed claim comes on the heels of a CMA investigation. That assumption would be misplaced, particularly in a stand-alone case.

There is now a substantial body of authority emphasising that certification is not a rubber-stamping exercise, especially in stand-alone cases. The Tribunal will scrutinise all aspects of the application, including: (i) the proposed common issues; (ii) the loss methodology; (iii) the credibility and class-wide applicability of the counterfactual; (iv) the suitability of the proposed class representative; (v) the funding arrangements; and (vi) the proposed approach to damages distribution.

Another central issue is likely to be the definition of the proposed class, and whether it is said to encompass all purchasers of new-build homes over a defined period, or only purchasers of properties developed by the investigated housebuilders. Geographic and temporal distinctions may also be required, given the localised nature of housing markets and the timing of the alleged conduct.

These questions go directly to commonality and manageability. Housing markets are inherently local. Pricing, incentives and sales practices vary materially by location and over time. Any attempt to aggregate claims across developments and regions will require an economic methodology capable of accommodating that variation without collapsing into individualised assessment.

Funding and strategic pressure

The claim is reportedly supported by third-party litigation funding from Burford Capital, a well-established funder in the UK collective actions market. As with other funded opt-out claims, the presence of third-party funding introduces an additional set of commercial incentives, including funder economics and return thresholds, which can shape litigation strategy and settlement dynamics.

Conclusion

The proposed opt-out collective action against UK housebuilders is likely to be one of the most closely watched cases of 2026.

The proximity of the proposed claim to the CMA’s decision is not coincidental. It reflects a now well-established trend in UK competition litigation in which regulatory scrutiny — even where it stops short of an infringement decision — is treated as a potential springboard for large-scale private damages claims. Earlier collective proceedings have drawn on market studies, sectoral reviews and regulatory investigations as part of the factual matrix relied upon at certification.

The Tribunal has accepted that such material can form part of the relevant background and may assist in demonstrating that a claim is not speculative. However, regulatory concern is not a substitute for pleaded infringement, and it does not relieve a class representative of the obligation to advance a coherent and workable case capable of clearing the demanding certification gateway.

For the housebuilders, the proposed claim comes at a time of sustained regulatory and policy pressure on the sector, including fire safety remediation obligations, the self-remediation contract and the forthcoming Building Safety Levy. It underscores the cumulative pressures facing the industry and the environment in which any litigation will be defended.