Interactive Investor

ISA millionaires at ii jump to record 1,001

The not-so-secret sauce to becoming an ISA millionaire: time, patience and investment compounding.

12th February 2024 09:59

by Myron Jobson from interactive investor

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  • The age of an interactive investor ISA millionaire is 74, compared to an average age of 57 for the overall ISA cohort
  • Some 65% of ii’s ISA millionaires are male, and 35% female, which is in line with ii’s wider ISA customer base
  • Early birds: 40% of the total 12-month subscriptions from ii’s ISA millionaires were added between 6 and 30 April in 2023
  • Flat-fee benefit: ii ISA millionaires monthly platform fee remains constant as the value of their investments grow. They keep more of what they make
  • Investment trust accounts for over 40% of typical ISA millionaire portfolio
  • Data shows that the ISA millionaire status is typically achieved through a well-diversified portfolio rather than cherry-picking risky bets.

The number of ISA millionaires on interactive investor, the UK’s second-largest investment platform, has soared to a record high of 1,001, following a bumper year for investments.

The total (as at 31 January 2023) is up 17% from the 852 recorded at the same time last year, and the average age of an interactive investor ISA millionaire is 74 compared to an average age of 57 for the overall ISA cohort.

Crucially, instead of charging a percentage fee on customer wealth, interactive investor charges a flat monthly fee, meaning our ISA millionaires have been able to keep more keep more of their wealth, even as the value of their portfolio increased. These savings can be substantial and life-changing over a lifetime of saving. 

Our ISA millionaires are likely to have benefited from a productive year for investments. The most recent interactive Investor Private Performance Index shows the average customer with a seven-figure portfolio (not specific to ISA millionaires) returned 9.3% in 2023 – outstripping the aggregate amount achieved by those with lower-value portfolios (8.3% median average).

Myron Jobson, Senior Personal Finance Analyst, interactive investor, says: “With the average age of 74 for ISA millionaires on our platform, it is clear that time, patience and the magic of compounding returns are the not-so-secret strategy to becoming an ISA millionaire. Admittedly, you’d need to be able to afford to invest significant sums, but the principal of patience and diligence is also enriching for those investing more modest amounts.

ISAs have been a game changer for wealth generation, creating thousands of millionaires – a large proportion of which invest through interactive investor, benefiting from our flat fees which don’t penalise them for achieving investment growth. Over a lifetime of investing, the differences between flat fee and percentage-based platform charges can add up to tens of thousands of pounds.

“Minimising the amount you pay to invest, as well as periodically reviewing and rebalancing your portfolio, can help speed up wealth generation.”

How ISA millionaires invest

ii ISA millionaires have a higher-than-average weighting to investment trusts. These account for 42% of the average portfolio – greater than the average of 24% for our broader ISA customer base. This comes at the expense of funds, which make up 11% of the seven-figure ISA portfolio – over 50% less than the average for ii’s broader ISA customer base (24%).

Our ISA millionaires also notably have a relatively modest weighting to cash in their ISA, accounting for under 5%, on average – almost half that for the broader ISA customer base (8%). This suggest that while cash plays an important role in portfolio diversification, our ISA millionaires are intrinsically focused on investing.

AUA in ISA by Instruments (All)


(in ISA)


(in ISA)













Investment Trusts






Source: interactive investor.

Gender breakdown

Some 65% of ii’s ISA millionaires are male, and 35% female, which is in line with ii’s wider ISA customer base. The average ISA millionaire age is 74 for both sexes.

Both sexes have a similar portfolio asset allocation – although female ISA millionaires have more in investment trusts then men (43.6% versus 40%), and less in direct equities (34.1% versus 40.5% for men).

When picking individual stocks, women have more UK exposure (90.26% versus 83.45% for men). 

The average male ISA millionaire makes almost 13 more trades a year than female peers (26.6 versus 14).

When do ISA millionaires invest and how often?

ii’s ISA millionaires typically make the most of the reset ISA allowance at the start of the new tax year. Some 40% of the total 12-month subscriptions from ii’s ISA millionaires were added between 6 and 30 April in 2023 – compared to 23% among all ii ISA customers.

Those long-term early bird investors will have had close to an additional year in the market, which will also help power portfolios in a rising market.

ISA millionaires made more than four times the number of trades on average (22), than were recorded across all ISA accounts on ii (5). This may well be for rebalancing purposes.

Myron Jobson says: “Our data shows that the ISA millionaire status is typically achieved through a well-diversified portfolio rather than cherry-picking risky bets. 

“Millionaire ii ISA holdersalso tend to be early bird investors, giving their money more time in the market to work hard for them and reap the rewards from compounding returns. Another good option is to drip feed your investments on a monthly basis to remove some of the risk of market timing, and it is also well suited to those with smaller sums to invest.

Most-held investments among ISA millionaires

All but one of the top 10 holdings (by number of customers holding) among ii’s ISA millionaires feature on the equivalent list for our broader ISA customer base.

Both cohorts favour UK blue-chip companies that pay a dividend, accounting for nine out of the top 10, respectively. The only outlier is investment trust Scottish Mortgage Ord (LSE:SMT) (which also pays a small dividend), which is the second most-held investment among ii’s ISA millionaires (fourth among broader ISA cohort).

Top 10 most held investment (by number of customers holding) among ii ISA millionaires and broader ii ISA cohort. Source: interactive investor.

Richard Hunter, Head of Markets at interactive investor, says: “For the most part, the top 10 list reflects a number of investment recommendations in action which have clearly been to the benefit of our investors.

“Investing for the long term and thus riding out the inevitable twists and turns, picking mature, cash-generative and stable blue-chips while also diversifying, and reaping the rewards of the power of compounding through any number of higher-yielding blue chips. 

“The list also provides exposure to the US and the latterly rampant big technology stocks in particular through holdings of both Alliance Trust and Scottish Mortgage.”

These articles are provided for information purposes only.  Occasionally, an opinion about whether to buy or sell a specific investment may be provided by third parties.  The content is not intended to be a personal recommendation to buy or sell any financial instrument or product, or to adopt any investment strategy as it is not provided based on an assessment of your investing knowledge and experience, your financial situation or your investment objectives. The value of your investments, and the income derived from them, may go down as well as up. You may not get back all the money that you invest. The investments referred to in this article may not be suitable for all investors, and if in doubt, an investor should seek advice from a qualified investment adviser.

Full performance can be found on the company or index summary page on the interactive investor website. Simply click on the company's or index name highlighted in the article.

Please remember, investment value can go up or down and you could get back less than you invest. If you’re in any doubt about the suitability of a stocks & shares ISA, you should seek independent financial advice. The tax treatment of this product depends on your individual circumstances and may change in future. If you are uncertain about the tax treatment of the product you should contact HMRC or seek independent tax advice.

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