There are also signs of home bias. UK-focused funds account for over a fifth of total fund assets, putting them comfortably ahead of North America. That doesn’t tell the whole story, though: US companies will also make up a substantial proportion of most global funds, so exposure to the region is likely to be considerably higher.
Before drawing too many conclusions, it is also worth remembering that becoming an ISA millionaire is not only about investment selection. Time in the market, regular contributions and the power of compounding are also likely to have played a major role in building these portfolios.
How many investments do they hold?
What is the right number of investments to hold in your ISA? Too many, and you risk complication and unnecessary fees. Too few, and your portfolio might be too concentrated. There is no magic number.
On average, ISA millionaires hold 18 investments, spread across funds, stocks, investment trusts and ETFs. When you break down the numbers, this equates to between one and two funds per £100,000.
Averages do not do justice to the huge variety of approaches on display, however. Some ISA millionaires hold just two funds. Others have almost 600 holdings, consisting mainly of individual stocks.
How much do they invest every year?
You can add up to £20,000 a year to an investment ISA – and bigger contributions obviously make it easier to grow your pot.
Not all ISA millionaires are maxing out their allowance, however. In 2025, they contributed £14,600 on average.
What are their favourite funds and stocks?
Consistent contributions and compounding do a lot of the heavy lifting in investing. Choosing the right investments is also key to success, however. As such, we have tracked down the 10 favourite funds and stocks of ISA millionaires in 2026.
Top 10 ISA millionaire funds
- Fidelity Global Special Situations Fund
- Fidelity Special Situations Fund
- Legal & General UK Index Trust Fund
- Fidelity Index World Fund
- Legal & General Global Technology Index Trust
- Fidelity Index UK Fund
- Fidelity European Fund
- Legal & General US Index Trust
- Fidelity Index US Fund
- Legal & General European Index Trust
Top 10 ISA millionaire stocks
Source: Fidelity International. Based on total asset values for Fidelity Personal Investors holding at least £1m in their portfolio between January and July 2026.
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