The Alternative Investment Market (AIM) hosts junior companies on the London Stock Exchange. Its main function is to provide a listing before companies grow and migrate to a main listing. In this guide, we cover how to buy AIM shares, what the AIM market is and some of the best AIM shares to follow.
Small-cap AIM stocks tend to be higher up on the risk spectrum. But they can be worth including in a Stocks or Shares ISA or SIPP due to their potential for outsized returns. Looking for the best AIM stocks to buy for 2025? Here are three shares to take a look at.
Cerillion
Cerillion (CER:LON) is a technology company that specialises in back-office software for telecoms companies. It has been one of the AIMβs best performers in recent years, delivering a gain of nearly 600% since the start of 2020.
This company is benefitting as telcos across the world invest in software to increase efficiency. Over the last five financial years, its revenue has climbed from Β£18.8 million to Β£43.8 million. Looking ahead, further top-line expansion could push the share price higher. For the year ending 30 September 2025, the consensus revenue forecast is Β£49.5 million.
Now, one downside to this AIM stock is that its valuation is relatively high. Currently, its forward-looking price-to-earnings (P/E) ratio is about 31. I believe this valuation is justified given the software companyβs strong growth track record. But it does add some risk to the investment case β if growth slows down the stock could be volatile.
Edward Sheldon owns shares in Cerillion
YΓΌ Group
If one is looking for a cheap AIM stock to buy for 2025, YΓΌ (YU:LON) could be worth checking out. Itβs an independent supplier of gas and electricity to businesses across the UK, and a smart metre installer.
This company has been growing at a fast pace recently. For the first half of 2024, YΓΌβs revenues climbed 60% to Β£313 million while earnings per share (EPS) increased 52% to 88p.
But this business momentum doesnβt seem to be reflected in its valuation. Currently, the stock trades on a forward-looking P/E ratio of just nine.
The low valuation isnβt the only attraction here, however. Another is the companyβs rapidly-growing dividend. In its interim 2024 results, YΓΌ increased its dividend by 533% to 19p. Currently, the yield is around 3.5% but if YΓΌ continues to increase its payout aggressively, the stock could become a cash cow.
Itβs worth pointing out that YΓΌ operates in a competitive market and has no control over energy prices. So, thereβs no guarantee that it will continue to have success. I like the risk/reward setup at current levels though.
- Do you prefer larger-cap stocks? See our picks of the best FTSE 100 stocks.
hVIVO
Finally, I think out of favour hVIVO (HVO:LON) is worth considering as a contrarian play. Itβs a small company in the healthcare sector that offers services for clinical trials and lab testing (and works with four of the top 10 pharma companies globally).
This AIM stock has come under pressure recently due to the fact that Robert Kennedy Jr has been selected to lead the US Department of Health and Human Services. Heβs a notorious vaccine sceptic and there are fears that major pharma companies could face a hostile regulatory/funding environment while heβs around.
I think the fears are probably overblown though. Realistically, pharma companies are likely to continue developing vaccines and drugs, and they will require clinical trial services such as those offered by hVIVO.
After its recent share price fall, this stock looks cheap. Currently, the forward-looking P/E ratio is just 11. Given that the company has just opened a new state-of-the-art facility in Canary Wharf and is targeting revenues of Β£100 million by 2028 (versus a forecast of Β£62.5 million for 2024), I see a lot of value at that multiple. Taking a medium to long-term view, I think this small-cap stock has considerable potential.
What is the AIM stock market?
AIM was set up in 1995 to promote investments in risky corporate ventures. Because of its less onerous listing requirements, many new startups choose to list there. Liquidity has grown as AIM shares can be included in stocks and shares ISAs, making them attractive tax-wise.
- Related guide: Compare the best stocks and shares ISA accounts
According to the latest statistics (December 2024) from the FTSE AIM All-Share Index, AIM currently has 610 companies (down from a peak of 1,694 in 2007) with an overall market capitalisation of Β£68 billion (down from Β£104 billion in March 2019). Despite the decline in the number of companies and overall value, it remains a stock market worth considering for investment.
Related guide: How to buy shares in any company from any stock market around the world.
How to buy AIM shares
To buy AIM shares you need a stock broker that provides access to smaller-cap shares.
These are what we think are some of the best stock brokers for investing in AIM stocks and why:
- Hargreaves Lansdown β excellent market access, research pricing data and AIM company reports
- Interactive Investor β provide a fixed-fee investing account and access to the AIM market
- AJ Bell β a low-cost investment platform for investing in AIM shares
- IG β investing, CFD trading and financial spread betting on AIM stocks
- Spreadex β a smaller derivatives broker with great customer service for working orders in between the bid/offer spread (for more advanced larger traders).
Buying AIM Shares with direct market access (DMA)
If you want better pricing, you can buy shares on the AIM market inside the bid/offer spread to get better pricing and reduce trading costs.
The answer to this question concerns limit orders, that is an order to buy or sell a security at a specific price and typically one that is different to the prevailing bid-offer spread. The difference between the price at which you can sell and the price at which you can buy in that security.
More specifically the reader asked whether itβs possible for retail traders and investors to leave a limit with a broker, that is inside the bid-offer spread. Because as they point out in UK smaller companies and AIM-listed stocks, that spread can be as much as 10% of the share price.
This, of course, means that if an investor buys a stock with a 10% bid-offer spread they need to see to see the stock price rise by 10% before they break even.
Being able to place limit orders, and trade inside the bid-offer spread could reduce this break-even hurdle quite significantly.
Whatβs more, we were asked could limit orders be placed, if you are dealing for a stocks and shares ISA or SIPP account and can this be done electronically.
I put these questions to several of the UKβs leading investing platforms.
The answer is that clients can leave limit orders, for example, Charlie Musson, Brand Director at AJ Bell told us limit orders can be placed for any UK share that is traded in sterling, and that they can be placed online, using either the website and mobile app or via the telephone.
Mr Musson also noted that a limit order can be placed with AJ Bell for ISA, pension and general investment accounts.
Itβs even possible to place limits on international stocks with the broker, over the phone. Though certain restrictions around order size and liquidity in the underlying will apply here.
Limit orders at AJ Bell will not be automatically shown to the markets, and will instead be monitored in house, for a period of up to 90 days. Limits are transmitted to the market for execution if and when the bid offer price moves to a point where the order coud be executed, however an execution is not guaranteed.
At Hargreaves Lansdown clients can leave limit orders online, using the HL Live App and they can do so for all LSE-listed equities, including AIM stocks, ETFs and Investment Trusts.
Clients can choose from buy or sell limit order types, these orders are valid for 90 days. During this time they can be monitored within the pending orders section of the clientβs online account.
I note though that these orders are minded internally, which means that the potential trade is not live on the order book, or left with a market maker, in a quote-driven stock, to be executed against their order flow.
Hargreaves Lansdown clients can also place limit orders over the telephone with the firmβs dealing team, in any security offered by the broker, that has a secondary market, subject to the counterparties in that market being willing to accept such an order.
These telephoned limit orders can be left on a good-for-the-day basis and clients can also specify βall or nothing, βpartial fillβ or βminimum fillβ requirements, when they place their order, phone dealing charges apply. Hargreaves will use their expertise and judgement to try and achieve a fill for the client. However, once again an execution is not guaranteed and Hargreaves Lansdown points out that it does not offer a DMA service.
DMA or Direct Market Access offers clients the ability to interact directly with the order books of the LSE SETS trading systems.
However, many retail brokers donβt operate a DMA service because of the structural, regulatory, technological and cost implications of doing so which are significant in each case.
Instead, retail brokers often have access to whatβs known as the RSP, an online trading network run by the London Stock Exchange that allows market makers to compete for retail flow on a order by order basis.
Market makers on the RSP can choose to make price improvements in a given stock or stocks, whilst brokers can poll the RSP electronically with pricing requests, and if a limit order falls within a price improvement offered via the RSP, then that limit order should be executed.
At Interactive Investor, which is now owned by abrdn, clients can also place limit orders online, or over the telephone and this facility includes AIM-listed stocks.
However, that limit will not be made public or exposed to the market. Instead, it will be minded in-house until such time as it can be executed. II do make this point clear to clients when they submit limit orders.
Once again this is an important distinction, because it means that market makers in a security will be unaware of the limit orders existence and therefore will have no opportunity to fill it, even if they wanted to.
However, Interactive Investors are able to expose limit orders to the market on request, on a case-by-case basis, and clients will need to call the dealing team to initiate this, however, different dealing charges are likely to apply.
Getting a limit order executed will depend on a variety of factors such as the size of your order, the level of liquidity and activity in the security in question and even the relationship your brokerβs dealing team have with the market makers in that stock.
In summary then limit orders can be placed with the large stock brokers, however there are limitations to this process, and investors need to be aware of what they are before they use this order type.
It also depends on the size of your account, the relationship you have with your broker and what sort of volume are trading.
The ultimate answer is that if you have an investing account, phone up your dealer and ask nicely. They may then phone up one of their market maker friends and see if they can work a bid below the offer for you.

Based in London, Edward is a distinguished investment writer with an extensive client portfolio comprising a diverse array of prominent financial services firms across the globe. With over 15 years of hands-on experience in private wealth management and institutional asset management, both in the UK and Australia, he possesses a profound understanding of the finance industry.
Before establishing himself as a writer, Edward earned a Commerce degree from the prestigious University of Melbourne. Complementing his academic background, he holds the esteemed Investment Management Certificate (IMC) and is a proud holder of the Chartered Financial Analyst (CFA) qualification.
Widely recognized as a sought-after investment expert, Edwardβs insightful perspectives and analyses have been featured on sites such as BlackRock, Credit Suisse, WisdomTree, Motley Fool, eToro, and CMC Markets, among others.
You can contact Ed at edward@goodmoneyguide.com