The number of Isa millionaires investing through the stockbroker AJ Bell has surged by 74% over the past year, according to recent disclosures.

Between December 2024 and December 2025, AJ Bell experienced a significant increase in the count of Isa millionaires using its platform. However, the company has not disclosed the precise figures for how many investors have joined this elite group.

Isas have gained immense popularity in recent years, with at least 5,100 Isa millionaires currently residing in the UK. This figure likely underestimates the true number, as the most recent data only covers up to April 2023.

Investors have parked nearly £500 billion in stocks and shares Isas, and recent statistics indicate that about 2.5 million individuals are maximizing the £20,000 annual contribution limit.

AJ Bell has shared insights into the characteristics of its most successful investors, including the age at which they achieved Isa millionaire status and the diversity of their investment portfolios.

The number of Isa millionaires investing with AJ Bell ballooned 74 per cent between December 2024 and December 2025

What do they invest in?

A common trait among Isa millionaires is their greater propensity to hold individual shares compared to the average investor.

Funds and ETFs are less popular with Isa millionaires. This is because many are experienced investors and expert stock pickers who have conviction in their own ability to choose winning stocks, AJ Bell says.

Isa millionaires on AJ Bell’s platform hold, on average, 83 per cent of their portfolios in shares, including investment trusts, with most of the rest in funds. 

By comparison, this figure is 58 per cent in stocks across other Isa holders.

Oil giant Shell is the single most popular stock among the biggest Isa investors, taking the top spot in the list of most popular holdings for the last two years running.

Isa millionaires are also drawn to blue chip names on the UK stock market, including household names which have been around for decades like banking group Lloyds and life insurer Legal & General. 

Income-seeking investors also tend to look to FTSE100 companies for the high yields on offer. 

Investment trusts also have a place in Isa millionaires portfolios, according to AJ Bell. 

The most popular investment trusts held by Isa millionaires are Scottish Mortgage, Alliance Witan and JPMorgan Global Growth & Income. 

‘A preference to back mature, established businesses over start-ups might reflect the typical older age of an Isa millionaire,’ says Dan Coatsworth, head of markets at AJ Bell.

Isa millionaires hold, on average, 23 different positions within their portfolios, although this differs dramatically depending on the investor. 

Some hold over 150 different investments, while a handful have just a single investment in their portfolio.

How old are they?

It can take decades of dedication to become an Isa millionaire, reflected by the fact that the majority of Isa millionaires investing with AJ Bell are in their 60s and 70s. 

The average age of an Isa millionaire with AJ Bell is 70.

Dan adds: ‘With an average age of 70, many stocks and shares Isa super investors 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.’

But this does not mean no younger investors have hit the £1million milestone.

Some successful Isa investors managed to get to their first Isa million before turning 40. While the youngest Isa millionaire on AJ Bell’s platform is just 33 years old.

The most successful Isa investors have racked up their second Isa million before they turned 50.

Mr Coatsworth says: ‘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.’

On the other end of the scale, some of AJ Bell’s Isa millionaires are in their 90s. The oldest Isa millionaire investing with AJ Bell is a centenarian of 100 years old.

The average age of an Isa millionaire on AJ Bells platform is 70 years old

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