- AJ Bell looks at what it takes to become an ISA Super Investor in Stocks and Shares ISAs, Junior ISAs and Lifetime ISAs
- The number of Stocks and Shares ISA millionaires on the AJ Bell platform increased by 74% between December 2024 and December 2025
- There are also more Junior ISA and Lifetime ISA Super Investors this year compared with last year
Dan Coatsworth, AJ Bell head of markets, comments:
“After a year that saw global markets hit new record highs, the number of Stocks and Shares ISA millionaires on the AJ Bell platform increased by 74% in 2025.
“With an average age of 70, many Stocks and Shares ISA Super Investors with AJ Bell will have built their portfolio over decades and may have originally held investments in PEPs (Personal Equity Plans) before the introduction of ISAs over a quarter of a century ago.
“The majority of ISA millionaires are in their 60s and 70s, illustrating the crucial impact of compound returns over the long term – but that does not mean no younger investors have hit the milestone.
“Some successful ISA investors have even managed to accrue an ISA million before turning 40. The youngest ISA millionaire on the platform is just 33 years old. Astonishingly, some extremely successful ISA investors have racked up their second million before they hit 50. Although, it’s worth pointing out those with a sizeable portfolio at such a young age often tend to pursue a high conviction strategy focused on specific stocks, which won’t be for everyone.
“A number of ISA millionaires are in their 90s, with the oldest ISA millionaire on the AJ Bell platform being 100 years old, demonstrating that for many people long-term ISA investing will mean they’re able to leave a sizeable financial legacy for their family.
Source: AJ Bell.
“The Super Investors tend to be much more likely to hold shares than the typical investor. Among the ISA millionaires on AJ Bell’s platform, the account holders average 83% in shares (including investment trusts), with most of the rest in funds. By comparison, the figure is 58% across other ISA holders.
“Oil giant Shell is the single most popular stock among the wealthiest ISA investors, retaining top spot in the list of most popular holdings.
“ISA Super Investors hold on average 23 different positions within their portfolios, although this differs dramatically from one investor to the next. Some hold over 150 different investments, while a handful have just a single investment in their portfolio.”
Source: AJ Bell. Percentage of Stocks and Shares ISA customers with a balance of £1 million or more holding each security.
Junior ISAs
“The data also examines Junior ISA holders on the AJ Bell DIY investment platform that have built up a large account worth £100,000 or more. The youngest Junior ISA holder with £100,000 or more to their name is just six years old, although most are in their teens and will have benefitted from contributions made to their account since birth.
“AJ Bell’s Junior ISA Super Investors tend to hold fewer positions in their portfolio than their older ISA millionaire peers, with the most popular investments including Scottish Mortgage, the Fundsmith Equity fund and Legal & General, as well as tracker funds including the iShares FTSE 100 and S&P 500 ETFs.
“It was a record-breaking year for the FTSE 100 in 2025, and Junior ISA Super Investors reaped the rewards with many of the most popular stocks in large Junior ISA portfolios, such as Lloyds, GSK and BP, hailing from London’s blue-chip index.”
Lifetime ISAs
“Lifetime ISAs are one of the most recent iterations of the ISA product, with the government introducing them from April 2017. As a result, investors have had less time to grow such sizeable accounts. Nonetheless, thousands have built accounts worth more than £50,000.
“The youngest Lifetime ISA Super Investor is just 21, putting them within touching distance of the average first-time buyer deposit of around £60,000*.
“Some of the largest Lifetime ISAs are worth over £300,000, a remarkable sum and an astonishing return given that investors can only deposit a maximum of £5,000 a year including the government top-up. Like their ISA millionaire peers with the biggest accounts, these investors tend to have backed a small number of high growth stocks, which is a risky investing strategy that can offer huge rewards if you get it right.
“But ordinary investors shouldn’t misinterpret this as a sign they ought to back one or two stocks in the hope of hitting the jackpot – this strategy can deliver massive returns but there’s also a danger that the stocks underperform and you lose money. If you pursue a high-risk strategy you must do so with your eyes wide open, and for most people it’s best to hold a diversified mix of investments.”
What can you learn from the ISA millionaires?
“ISA millionaires are a fascinating group and they can teach us a few things about the basics of investing, as well as providing a tantalising glimpse of what’s possible through a combination of regular contributions, patience and perhaps a bit of good fortune too.
“The most obvious lesson is that time is a crucial ally when it comes to investing. Most millionaires tend to be older because they’ve benefited from decades of compound growth and years of contributions. If you aspire to amass an ISA million, it’s best to get started as early as possible and do so with a ‘get rich slow’ mindset. It’s true there are examples of the opposite – younger investors with a high risk appetite who have achieved huge returns – but ordinary investors are normally best served by a diversified portfolio held for the long term.
“Second, there is no guaranteed recipe for success. Some Super Investors invest in highly diversified portfolios, while others have just a handful of positions. And while shares and trusts are especially popular among ISA millionaires, there are plenty using funds too. The important thing is to invest in what you feel comfortable with and understand the level of risk you are taking in return for the potential reward.
“Finally, the success enjoyed by the Super Investors helps to illustrate the simplicity of ISAs. A straightforward financial product, ISAs allow you to invest in a range of assets in a single account, without worrying about dealing with the headache of income, dividend or capital gains taxes. Your total return is free from the taxman so you can invest hassle-free.”
*Lloyds Banking Group/Halifax: First time buyer market rebounds
