Comparing M&A in the UK and US: trends, challenges and outlook for 2025-2026

As London and New York continue to anchor global M&A, dealmakers on both sides of the Atlantic face differing market conditions shaped by regulatory frameworks, shifting finance dynamics and unique approaches to deal structuring. 

In the US, New York's M&A market is defined by deep capital markets, aggressive shareholder activism and a strong antitrust stance that shapes deal design and timing. Whereas in the UK, London blends a principles-driven takeover regime with increasingly assertive merger control and national security screening, set against a European-scale liquidity backdrop. 

Understanding these differences is essential for boards, sponsors and advisers navigating M&A deals in UK and US markets. In this article, M&A specialist and corporate partner Simon Dinning explores these key differences including regulatory compliance, shareholder activism and its impact on M&A strategies, plus the growing role of private credit and structured financing.  

Ogier is a leading adviser on high-value cross-border mergers and acquisitions. With experienced teams across leading international finance centres, we work with clients across sectors, borders and time zones. Simon practices Jersey and BVI law and has more than 25 years’ experience in advising on global M&A transactions from both an onshore and offshore perspective. 

M&A dealmaking in 2025 

Despite the differences in the UK and US, so far in 2025 we're seeing similar levels of M&A activity. Volumes are down but values are resilient, with megadeals propping up (or potentially skewing) overall totals.  

According to the latest M&A report by JP Morgan, the first half of 2025 saw a 12% increase in deals with a value in excess of US$10 billion, and deals in the US$1 billion to US$10 billion space are up 30% year on year.  

However, the majority of deals are sub US$1 billion transactions and this is pushing practitioners in both London and New York toward creative structures and financing, including club deals and private credit. 

The impact of rules and regulations on M&A 

In the London market, public takeovers are governed by the Takeover Code, overseen by the Panel on Takeovers and Mergers. The Code’s “put up or shut up” (PUSU) discipline serves to shorten diligence and financing timelines, compared to many tender offer timelines in the US.  

The Code’s general principles and rules also necessitate equal treatment among shareholders and require cash confirmation for announced offers, shaping tactics in competitive processes and sponsor-backed bids. As a result, London deal teams are front-load financing and shareholder engagement well before any deal announcement. 

In terms of the competitive landscape, the Competition and Markets Authority (CMA) in the UK continues to take an assertive stance, including on global transactions with a UK nexus. The UK has also hardened its national security perimeter via the National Security and Investment Act (NSI), which mandates notifications in 17 sensitive sectors. The result is that advisers in the London market are having to treat CMA engagement and NSI filings as key priorities to a far greater extent than in the past. 

In the US, earlier moves by the Department of Justice / Federal Trade Commission (DOJ / FTC) Merger Guidelines to lower the thresholds at which authorities presume competitive harm were reinforced in 2025 . This has been done through the introduction of a more demanding pre-merger notification form under the Hart-Scott-Rodino (HSR) regime. As a result, parties planning US centred deals now must focus more time into antitrust workstreams up front, particularly in sectors such as tech, healthcare and industrials. 

US purchasers also face two gating items, the antitrust regime and national security review via the Committee on Foreign Investment in the United States (CFIUS). Indications are that enforcement action will remain robust through 2025 and beyond and so, particularly in sensitive sectors, navigating these two areas and mitigating concerns is a key issue early in deal discussions.

It remains to be seen whether the US Treasury's fast track process, including the known investor portal, will genuinely impact the investment landscape and fulfil its aim of facilitating greater investment in US businesses. 

Financing M&A deals in the UK and US 

In 2025, financing has become a central determinant of M&A success, with dealmakers balancing higher interest rates, volatile debt markets and the growing dominance of private credit.  

Traditional syndicated loans and high-yield bonds remain important, but they are less reliable given tighter monetary conditions and uneven investor appetite. As a result, private credit providers now play a pivotal role, offering speed, confidentiality and certainty of execution. 

In both the US and Europe, deal structures increasingly feature multi-tranche solutions, club deals and hybrid instruments such as toggle notes and preferred equity. Currency flexibility has also become essential, with buyers in London often layering sterling, euro, and dollar debt to match investor bases.  

In the US, deep US$ liquidity still underpins the largest financings, though even here sponsors are hedging risk with private lenders. 

Equity financing still remains relevant, especially for strategic acquirers pursuing stock-for-stock mergers, but in a higher-rate world, debt efficiency and early financing certainty are paramount. 

Ultimately, M&A financing in 2025 is defined less by cost than by reliability, with sponsors paying premiums for structures that guarantee deal closure. 

Public markets and liquidity 

In 2025, the US capital markets remain the deepest and most liquid globally, making the US the preferred venue for equity-financed M&A. Large strategic acquirers can credibly pursue stock-for-stock or mixed consideration deals, and periodic openings in the high-yield and syndicated loan markets support multi-billion-dollar financings. This depth gives US buyers flexibility, even in a higher-rate environment. 

By contrast, UK capital markets are thinner, with lower trading volumes and valuation discounts relative to the US. This constrains the use of shares as M&A currency, so London deals often rely on all-cash offers. Financing certainty is provided through private credit, club lending or multi-currency debt packages.  

Although reforms in 2024 have improved London’s competitiveness, the gap in scale compared to New York remains. 

For M&A, the difference is clear: the US favours stock-driven strategic mergers and mega-deals, while the UK emphasises cash-backed bids with private equity playing a prominent role. We're seeing buyers adapt accordingly by using equity as a primary tool in New York, but prioritising debt certainty in London. 

Shareholder activism and its M&A impact 

In 2025, shareholder activism remains a powerful force shaping M&A, but its style and influence differ markedly between the US and UK. 

New York continues to be the epicentre of global activism, where hedge funds aggressively push for strategic change. Campaigns often lead directly to M&A outcomes, whether through forced sales, divestitures or contested takeovers. For example, Starboard Value and Third Point have targeted consumer and industrial names, driving spin-offs or encouraging boards to consider sale processes. 

The US regulatory framework makes proxy fights and board challenges easier, so activists can credibly threaten governance upheaval to extract concessions. As a result, activism frequently accelerates dealmaking. 

London has seen a steady rise in activism but, by contrast, campaigns tend to be more valuation-driven and consensus oriented. The UK Takeover Code imposes strict disclosure rules and the “put up or shut up” timetable naturally limits prolonged public fights. Recent examples include Bluebell Capital’s pressure on Glencore to separate its coal business and CIAM’s opposition to undervalued takeover offers, which contributed to improved bid terms.  

UK activists often focus on ensuring shareholders receive fair value in M&A, rather than forcing sales outright. Large institutional investors play a central role, requiring activists to build coalitions behind the scenes rather than rely solely on public campaigns. 

To summarise the effect of activism on both sides of the pond, US activism directly accelerates transformative transactions, while UK activism shapes deal pricing and terms within a structured regulatory framework. For buyers and boards, this means anticipating activist intervention is essential - whether as a catalyst for launching deals in New York or as a constraint ensuring value discipline in London. 

Shareholder activism is expected to remain a major influence on M&A in 2026, though trends in the US and UK are likely to diverge further. In both markets, shareholder activism will be a factor that target boards and purchasers need to consider at an early stage.

Looking forward 

As 2026 approaches, global M&A activity is expected to remain robust, though shaped by tighter financing conditions, evolving regulatory frameworks and changing strategic priorities.  

In the US, dealmaking will continue to be concentrated in underperforming sectors such as technology, healthcare, and industrials. Companies in these areas face operational pressures, competitive disruption and activist investor attention, making strategic acquisitions, divestitures, and spin-offs particularly attractive.  

Shareholder activism will continue to have an impact, often accelerating transactions or forcing boards to consider strategic alternatives. Activists are expected to increasingly integrate ESG considerations into their campaigns, pressuring companies to align M&A strategies with sustainability and social governance objectives alongside financial performance. Proxy contests, board challenges and campaign-driven negotiations will remain central tools in the US, shaping both deal timing and structure. 

In the UK, M&A activity is likely to grow more cautiously, with an emphasis on fair pricing, regulatory compliance and financing certainty. UK-listed targets will attract domestic and cross-border interest, though liquidity constraints and the Takeover Code’s procedural rules will shape timelines and announcement strategies.  

Shareholder activism is likely to grow more sophisticated in the UK, focusing more on valuation discipline and improved bid terms rather than forcing outright sales, with institutional investors playing a pivotal role in mediating outcomes. Cross-border bids could also see heightened activist involvement, especially where UK-listed targets face undervalued offers from foreign buyers 

Cash-backed transactions, often supported by private credit or club lending structures, will remain the predominant vehicle for mid-market and large public deals. 

Across both markets, financing certainty will be a key driver of deal success. Cash-backed transactions, often supported by private credit or club lending structures, will remain the predominant vehicle for mid-market and large public deals. 

Syndicated loans and high-yield instruments will remain available for larger transactions but will be more selectively used, depending on market sentiment. 

Overall, we expect to see 2026 feature targeted, high-quality transactions rather than broad-volume activity. Companies and investors will prioritise deals with strong strategic rationale, regulatory readiness and financing certainty. Navigating activism, competition reviews and shareholder expectations will be increasingly central to deal execution on both sides of the Atlantic, making preparation and agility key competitive advantages for buyers. 

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Disclaimer

This client briefing has been prepared for clients and professional associates of Ogier. The information and expressions of opinion which it contains are not intended to be a comprehensive study or to provide legal advice and should not be treated as a substitute for specific advice concerning individual situations.

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