More companies queue up to transfer from AIM to London’s Main Market as junior market approaches 30th birthday

AIM turns 30 on 19 June and its celebrations have been overshadowed by the shrinking number of companies on the market. While it is natural to see the tail end disappear as tiny companies cannot justify the cost of being listed, and takeovers across the market continue with pace, there is an underappreciated trend elsewhere.

The number of AIM companies shifting their listing to London’s Main Market so far in 2025 is at a three-year high (if all the intended ones complete) and we’re not even halfway through the year.

Textile rental expert Johnson Service Group and data analytics provider GlobalData recently declared their intention to move up to the Main Market; and asset manager Brooks Macdonald and tech firm Gamma Communications have already completed the transition earlier this year.

If all the companies complete their transfer, it would be the same number of transfers so far this year as the total number of stocks moving from AIM to the Main Market across 2023 and 2024 combined. It wouldn’t be a surprise to see more companies follow suit this year, potentially making 2025 one of the busiest years in the past decade for such movement.

Importantly, this trend is not necessarily a negative factor. One could argue AIM was designed to act as a stepping stone to the Main Market and it’s a positive that companies feel they’ve reached a level of maturity to move to the premier league.

Since 2004, AJ Bell calculates that 130 companies have moved from AIM to the Main Market. Many are now in the top tier indices and others have been taken over at a big premium to the market price.

Source: AJ Bell, LSE. *1 Jan to 10 June 2025.

Why Johnson Service Group is leaving AIM

Johnson Service Group was previously a Main Market-listed company in a different form, but various circumstances led it to move to AIM.

Just under 20 years ago, the business wasn’t in a good financial shape due to operational issues and poor management decisions. That led to the sale of its workwear business and a change in leadership.

Moving to AIM helped to cut listing costs and coincided with a period where the group had to work hard to get back on its feet. Fast forward to the present and it’s doing much better, hence the move back to the Main Market.

Johnson Service Group intends to switch markets in August, saying it would enable access to deeper pools of capital and a broader range of investors, as well as increase liquidity in its shares, and boost its corporate profile.

Further reasons why companies move from AIM to the Main Market

Despite having a plethora of success stories, AIM suffers from a stigma related to various corporate failures and scandals which have tarnished its reputation. Sometimes companies just want to distance themselves from this negativity and moving to the Main Market is not only a solution, but also a badge of honour in the business and investment world.

Being listed on the Main Market can increase a company’s profile among the public and its peer group, which can lead to greater media coverage and potentially more analyst research coverage of the stock. A lot of investors dismiss AIM stocks, believing it to be a market full of tiny companies, whereas Main Market stocks are often considered to be more established businesses.

Moving from AIM to the Main Market can also attract a new type of share buyer for companies of a certain size. Qualifying for the FTSE 250 or FTSE 100 would trigger tracker funds to buy the stock, creating additional demand for the shares.

Examples of big-name companies that moved from AIM to the Main Market

Plenty of big names on London’s Main Market started out on AIM, including gambling group Entain (previously called GVC when it was an AIM stock), engineer fixer-upper Melrose and student housing group Unite, all of which are now FTSE 100 stocks.

Other AIM alumni include construction group Breedon, the UK part of fast-food chain Domino’s Pizza, and genetics specialist Genus, all of which now sit in the FTSE 250 index.

Examples of ‘movers’ that were subsequently taken over

Numerous stocks transferring from AIM to the Main Market have subsequently been taken over as moving to the more prominent exchange can often signify a company that’s going places. Larger companies often look at the mid-cap space for acquisitions to augment their own growth, either buying smaller rivals or a company that takes them into a new area.

For example, Tesco secured a strong foothold in the wholesale market through its £3.7 billion acquisition of Booker in 2018. Booker had previously moved up from AIM to the Main Market in 2009, at which time it was valued at approximately seven times less than what Tesco subsequently paid to acquire it.

Other AIM-to-Main Market alumni include Peppa Pig rights owner Entertainment One which was acquired by Hasbro for £3.3 billion in 2019, and last year gold miner Centamin was bought by AngloGold Ashanti for £1.9 billion.