London Calling: Opportunities for US Companies on the London Stock Exchange

London has long been a leading destination for companies, particularly growth companies, looking to go public. In 2024, companies listed on the London Stock Exchange’s (“LSE”) markets raised an aggregate of US$32.5 billion - the fourth highest amount of any market, behind only the US, India and Japan and outstripping the combined volume of Frankfurt, Paris and Amsterdam. Recent reforms have also made the London markets simpler and more flexible than ever for companies looking to raise capital, execute M&A transactions and attract international investment.

In this five-part series, we explore why US-incorporated and US-operated private companies would consider an initial public offering (“IPO”) on the London markets and the key considerations they need to evaluate when planning and preparing for such a listing.  

The full list of the articles in this series are:

1. Crossing the Pond: Why US Companies Should Consider London Listings
2. Guiding the Deal: The Role of a Corporate Finance Adviser
3. Getting the Numbers Right: Accounting Essentials for US Companies Listing in London
4. Building the Framework: Legal Considerations for a London IPO and beyond
5. Connecting with Investors: Pre- and Post-Listing Tactics

Crossing the Pond: Why US Companies Should Consider London Listings

Co-authored by Chris Mayo, Head of Primary Markets, Americas, at LSEG.

London has the most international issuer base of any major exchange. As of June 2025, 572 of the companies listed on the LSE - over 35% of the total - were domiciled outside of the UK. This is not surprising: over the last five years, London has been the largest market for equity capital raising outside of the US and Greater China. 

Many US-incorporated and US-operated businesses have chosen the LSE as their primary or secondary listing venue, and their reasons are as varied as the companies themselves. In this article, we will explore the reasons why a US private company might opt for a primary listing in London. 

$32.5 bn

Aggregate amount raised by companies listed on the LSE (2024)

Recent market activity

Since 2017, 57 US-incorporated companies and companies with their primary operations based in the US have listed on the LSE. At listing, those companies had a combined market capitalisation of US$67.9 billion and raised an aggregate of US$8.6 billion on admission. Currently, 67 US companies are listed in London with a combined market value of US$123 billion. 

$67.9 bn

Combined market capitalisation of US companies at time of listing on LSE (Jan 2017 - June 2025)

Examples of US companies that have successfully listed in London and leveraged the markets to raise funds and expand their operations include: 

• Boku, Inc., a US fintech company backed by a16z, Benchmark, Index, Khosla and NEA that raised US$60 million at IPO and grew from a market capitalisation of US$167 million at admission to more than US$875 million by September 2025. 
• MicroSalt plc, a Florida-based food-technology company commercialising patented low-sodium salt technology, was the first London IPO of 2024 and ended the year with a share price 79% higher than its IPO price.
• AOTI Inc., a US medtech company based in Oceanside, California, was the largest AIM IPO of 2024, raising US$44.6 million on admission (over 40% being a secondary selldown) and achieving a market capitalisation of US$177.9 million.
• Helix Exploration plc, a helium exploration company with operations in Montana, raised £7.5 million on listing, achieving a market capitalisation of £12.2 million, and saw a 75% increase on its share price by year-end. The company returned to the market in January and again in June of 2025, raising US$6.1 and US$6.2 million respectively - both at a premium to its IPO price.
• Rosebank Industries plc, an acquisition vehicle created by the founders of Melrose Industries plc listed on AIM in July 2024, raising US$64.0 million on admission. In August 2025, the company completed its first acquisition - of Missouri-based Electrical Components International (“ECI”) - and raised US$1.53 billion on AIM to finance the deal. On completion the placing was the largest ever completed on AIM and the largest primary placing in UK equity markets since 2020. 

Why would a US company consider the London markets to be a suitable listing venue?

“Which market?” is one of the first decisions a board must make when pursuing a public listing. This is a very personal decision for each company – there is no one-size-fits-all response. Each company must evaluate the specific opportunities available to it on each exchange in light of the company’s strategic objectives and growth aspirations.

What factors do the board need to think about?

The board of the company should assess the market’s suitability in a broad context. Key questions include:

• Which other companies are listed on the exchange and how do they compare in terms of size and stage of development?
• Is there an equity research capability in the jurisdiction for a company of this nature? 
• Is there a pool of institutional investors likely to invest in a company at this stage of development? What is the size of the likely pool, and are the investors of a type and quality the company would like to engage with and aligned with the company’s values and goals?
• What are costs and obligations associated with listing and ongoing compliance? 

The best approach is to weigh up the pros and cons of the options available to the company. Speaking with representatives of the exchange, advisers (including financial, regulatory and legal advisers), and the companies already listed on the exchange can provide valuable insights to guide the decision. 

What are the advantages of a London listing vs a US listing?

Listing on the LSE offers several advantages to US companies, particularly for early-stage and growth companies:

• Smaller company focus – The LSE operates multiple markets, each tailored to support companies at the different stages of their lifecycle. The LSE is keen to encourage early-stage, scale up and growth companies to engage with the public markets and the AIM market in particular has a strong track record of supporting smaller, growth-oriented businesses. From Q1 2018 through to H1 2025, the average market capitalisation of companies listing on AIM was US$126 million and on the Main Market was US$873 million – compared to US$1.6 billion on NASDAQ and US$4.1 billion on the New York Stock Exchange (“NYSE”). 

$126 m

Average market capitalisation of companies listing on AIM (Q1 2018 - H1 2025)

• High-quality, active, long-only institutional investor base - Unlike US markets, where smaller companies can struggle for visibility, London offers a strong active investor base specifically focused on growth opportunities.  The UK has Europe’s largest pool of dedicated capital - US$470 billion of assets under management - 2.0 times larger than the next largest country-dedicated capital pool. Additionally, London-listed micro-caps (companies under US$250 million market capitalisation) have a much larger percentage of active investment - 92% active compared to 41% in the US - leading to more attentive market support. 
  
  
• Lower listing costs – One of the most significant differences is the lower costs involved with the IPO process in the UK. A listing on a US market typically incurs an underwriting cost of at least 5-7%. of funds raised, whereas the equivalent process on the London markets will incur underwriting fees of 3-5 per cent. of the total amount raised. For offerings under US$100 million, total additional fees (excluding underwriting fees) are about 4-5 times greater in the US than in the UK.  These substantial cost savings can make a meaningful difference, especially for growth-stage companies where capital efficiency is paramount. 

• Reduced ongoing reporting obligations - LSE listed companies report to the market on a bi-annual basis, compared to quarterly reporting obligations imposed by US regulatory frameworks. The costs of maintaining a London listing therefore tend to be lower than those on US markets. There are also higher audit costs in the US due to additional financial disclosures needed to comply with some provisions of the Sarbanes-Oxley Act – these do not apply to a London listed company. Legal and insurance costs also tend to be much higher in the US due to a much higher risk of litigation. We consider the accounting and legal perspectives in more detail later in this series.

• Lower litigation risk – The UK legal framework differs significantly from that of the US, with securities litigation being more common in the US - 3.9% of all US exchange listed companies were sued in 2024, with 225 new securities class action lawsuits filed that year. Since 2008, only five class actions (including group litigation orders, which are the closest UK proxy for class action lawsuits) have been filed against companies listed in London, with the Court ruling in favour of the company in two of those cases.
  
  
• Broader access to capital - London-listed companies raise follow-on capital more frequently and across a broader range of sectors than their US counterparts. In 2024, 54% of US micro-cap companies listed in London raised follow-on capital. Between 2021 and mid-2025, eight sectors have contributed at least 5% to total capital raised for UK listed microcaps. In the US during the same timeframe, 89% of the total capital raised by micro-caps was in the financials and healthcare space – with SPACs accounting for most. From 2019 to the end of June 2025, London-listed micro-caps were almost twice as likely to return for follow-on capital, with 60% of companies returning to market at least once and 37% returning to market multiple times.
  
  
• Receptivity to secondary selldown at IPO – UK investors are more open to secondary selldown – even at the point of IPO – than US investors, allowing founders and early investors to access significant liquidity earlier than would be possible on US markets. UK investors often view secondary selldown as an expansion of liquidity and are happy to support it if incumbent shareholders still retain an acceptable level of shareholding. What constitutes an acceptable level differs between companies and investors. Some of the largest private equity and venture capital funds have achieved partial exits when portfolio companies have listed in London. From 2020 to H1 2025, IPOs on AIM raising up to US$150 million had an average secondary component of 17% of the total deal size, compared to just 1% on NASDAQ and 2% on the NYSE. 
  
  
• Focus on quality over quantity: Whilst the plethora of smaller listings in the US can look like an indication that a company would be successful there, it is important to analyse the position in detail. Many US micro-cap IPO stocks are acquired by short-term investors looking for an opportunity to sell stock to high-turnover investors with commissions on those trades being collected by intermediaries. In contrast, in the UK smaller companies’ stock tends to be placed with high quality institutions that are looking to commit to the investment for the longer-term and to be there to support ongoing growth. It is because the UK institutional investor base is willing to pay attention to smaller companies that UK micro-cap IPOs historically have significantly outperformed US micro-cap IPOs – as of July 2025, UK micro-cap IPOs that occurred in 2024 have outperformed those in the US by 55%. In fact, a major US exchange recently mandated higher minimum IPO offer sizes in response to the poor performance of US listed micro-cap IPOs.  

“UK micro-cap IPOs historically have significantly outperformed US micro-cap IPOs – as of July 2025, UK micro-cap IPOs that occurred in 2024 have outperformed those in the US by 55%”

• More certainty through better price discovery mechanisms – The UK IPO process is more flexible and transparent than that of the US, leading to better price discovery and fewer IPO “pops”– when the stock price shoots up significantly on the first day of trading - post-listing. While many in the US view “pops” as a good thing, the reality is that they typically signify a misjudged IPO pricing and that the company has left money on the table. In London, IPO “pops” are rare, giving companies the peace of mind that they are maximising the value of their offering. 
  
  One reason why there are fewer “pops” in London listings is that companies can conduct early-look or “pilot fishing” meetings with investors to gauge initial interest without reporting to the UK regulator and spending a significant amount of money on adviser fees. This allows companies to get an accurate reading of investor demand early in the process and sets the stage for proper valuation. The US process has an equivalent called “testing the waters” but to implement this entails much more regulatory oversight and cost. Another benefit of a London listing is that both connected and unconnected analysts can publish deal research on the company, typically at the same time as the publication of the company’s ‘Intention to Float’ announcement. This allows investors access to in-depth insights and valuation models prepared by the research analysts to effectively evaluate the company as an investment opportunity prior to the listing and provide informed feedback to help price range setting for the IPO.
  
  
• Lower investor churn - The easy availability of price discovery mechanisms in London also means that there is much less investor “churn” on the first day of trading. Because of the active, long-term nature of the UK investor base and their ability to connect more meaningfully with companies earlier in the process, investors in the IPO are significantly less likely to sell shortly after listing.

Common objections to a London listing from US-based companies 

For US companies, listing on domestic exchanges might seem the obvious choice. While a US listing might be appropriate for some, it is not always the best option - especially for smaller companies. Many companies are drawn towards a listing on the US markets and the deep pools of capital available in the US. Experience suggests that this is often driven by the perception that: 

(i) the company is likely to achieve a higher valuation and greater liquidity on the US markets; 
(ii) a US listing is the best way to access the market with the largest pool of capital in the world; and/or
(iii) obtaining approvals which allow commercial access to the US market for certain industries might be easier with a US listing. 

Valuation & Liquidity

A common misconception is that there is a liquidity differential between the UK and US markets. This is usually because of analyses done using non-comparable metrics. When comparing the liquidity profiles of the London markets and the US markets, it is important to adjust for the differences in the free floats of the companies. Total daily value traded on the markets will likely show a large gap between US and UK liquidity metrics – but this is because of the size differential between the companies in the two markets. Companies in the S&P 500 are larger than those in the FTSE 100, resulting in larger free floats and therefore more value traded. When adjusted for free floats, the Average Daily Free-Float Adjusted Turnover Ratio shows that the UK and US liquidity profiles are comparable. 

It is commonly believed that companies trade at higher multiples in the US than in the UK. This is correct when comparing the aggregate price-to-earnings (P/E) ratios of the S&P 500 and the FTSE 100. However, it overlooks the differences in growth rates. When using a growth adjusted multiple such as price/earnings to growth (PEG), UK and US stocks are shown to trade broadly in line and many UK-listed growth companies trade at a premium to their US peers. The differences in valuation lie largely within the differences in growth rates. 

Access to US capital

A US listing may seem like a way to gain access to US institutional investors, but in practice the listing alone may not be sufficient - a market capitalisation of US$2 billion to US$5 billion is often quoted as a minimum range a company needs to achieve to gain interest from US institutional investors. Micro-cap companies listed in London have benefited from more active investor backing from institutional investors than their US-listed counterparts.

$873 m

Average market capitalisation of companies listing on the Main Market (Q1 2018 - H1 2025)

Regardless of the market a company opts for, US companies can still attract investment from US investors. The LSE boasts the world’s most geographically diverse investor base of any exchange, which can help US companies establish a truly global presence and attract investment from around the world. Approximately 41% of the investor base investing in UK listed companies is from North America. Many US institutional investors, including BlackRock and Capital Research, are active investors in the UK. Established mechanisms under US securities law allow companies not listing in the US to access US institutional capital, so if obtaining investment from US investors is an aim of the company, the board should discuss with their chosen corporate finance advisers how best to achieve this. 

Future plans – a stepping stone to the US

Some companies pursue a listing in the US because their operations are based there and they believe that approach makes sense due to the size of the US market or they perceive that approvals may be easier to achieve as a domestically listed company. While this may be the case, companies should consider the benefits that an overseas listing would offer, even where they may ultimately consider a move across to the US markets in future. 

Companies such as MaxCyte Inc., which first listed on AIM and then moved to NASDAQ demonstrate the value of this pathway. MaxCyte, Inc. successfully used the London markets to increase its market capitalisation from US$43.2 million to US$1.3 billion upon completing a NASDAQ listing and offering in July 2021. 

Diversified Energy Company (“DEC”) is another example. DEC floated on London’s AIM market in 2017 with a market capitalisation of US$86.1 million. In 2020 the company transferred to London’s Main Market and joined the FTSE 250. DEC raised ongoing growth capital while listed on both AIM and the Main Market. The company raised follow-on capital on five separate occasions while listed on AIM and completed eight acquisitions. Following the transfer to the Main Market, DEC has raised funds on six occasions and has completed a further 11 acquisitions. This demonstrates the ongoing access to capital that London offers for both smaller growth companies listed on AIM, as well as more mature Main Market-listed companies. In 2023, DEC added a NYSE listing and has a market cap of US$1.2 billion as of September 2025.

Similarly, Public Policy Holding Company (“PPHC”), floated on London’s AIM market in 2021 to fuel its acquisition-led growth strategy. In August 2025 PPHC announced plans to pursue a NASDAQ listing. PPHC has utilised its share capital as a public company to make seven acquisitions since its AIM IPO and has grown from a market capitalisation of US$193 million to US$312 million. Like DEC, PPHC will maintain its London listing, recognising the strategic advantages of a dual listing—including access to a broader investor base and the continued support of London’s international capital markets.

What to consider next

The London markets offer a compelling opportunity for US companies. Forward-thinking boards should consider the advantages that those can offer to them and their stakeholders. With its diverse pool of capital, supportive market infrastructure and lower regulatory burden compared to the US, the LSE provides a strong platform for growth. 

Completing a listing is just the beginning of a new stage of a company’s lifecycle - understanding the practical aspects of the listing process and the ongoing requirements as a listed company is crucial. In the rest of this series, we will explore these considerations in more detail and offer guidance on both the benefits and challenges of listing in London.

About The London Stock Exchange

The London Stock Exchange sets the stage for businesses to succeed. It is where ideas meet capital and become reality. Hosting 1,596 issuers with a combined market capitalisation of US$6.6 trillion, the LSE connects companies, countries, and investors in the real world to make measurable and positive differences across the globe.

For growing businesses looking for greater opportunities, governments delivering ambitious sustainability agendas or pension funds aiming to deliver higher returns to pension savers, the LSE helps businesses make the connections that can deliver real impact.

Customers look to the LSE for broad access to capital markets and liquidity across multiple asset classes. The LSE delivers a broad range of international equity, fixed income, exchange-traded funds/exchange-traded products, investment vehicles and foreign exchange markets. 

The LSE’s extensive experience, deep knowledge and worldwide presence across financial markets enables businesses and economies around the world to fund innovation, manage risk and create jobs.

Having contributed to supporting the financial stability and growth of communities and economies globally for more than 300 years, the London Stock Exchange is a catalyst for opportunity and sustainable growth.