Well known funds are most popular among self-invested personal pension investors using the Interactive Investor platform, with Fundsmith being the frontrunner.
According to Interactive Investor the Fundsmith Equity fund was the most bought fund in Sipps on the platform, followed by the Lindsell Train Global Equity fund.
The remaining funds on the list were from Vanguard, including its US Equity Index and LifeStrategy 60 funds.
About 2.5 per cent of Sipp accounts on the platform held £1m or more in assets.
The average age of a Sipp millionaire on the direct-to-consumer platform was 61 and the typical seven-figured portfolio was powered by funds (35 per cent) followed by investment trusts (29 per cent), equities (15 per cent), cash (8 per cent) and exchange traded products (8 per cent).
Of the investment trusts, Scottish Mortgage took the top spot ahead of Alliance Trust and RIT Capital Partners.
Stocks that pay out dividends tended to be the most popular stocks, with Royal Dutch Shell coming in first followed by Lloyd’s Banking Group and GlaxoSmithKline.
The most popular funds, investment trusts, ETPs, and stocks among Interactive Investor’s Sipp millionaires:
Exchange Traded Product
iShares Core FTSE 100 UCITS
Royal Dutch Shell
Lindsell Train Global Equity
WisdomTree Physical Gold
Lloyds Banking Group
Vanguard FTSE Developed World ex UK
RIT Capital Partners
iShares Physical Gold ETC
Vanguard LifeStrategy 60
Finsbury Growth & Income
Vanguard FTSE 100 UCITIS ETF
Vanguard US Equity Index
Vanguard FTSE 250 UCITS ETF
Source: Interactive Investor
Although pension savings are meant for the long term, interactive investor’s Sipp clients tended to change their investment portfolio frequently, the platform stated.
Of the 82 per cent who invested in the previous 12 months, 45 per cent altered their portfolio at least once a month and 23 per cent switched investment strategy at least twice a month on average.
Moira O’Neill, head of personal finance at Interactive Investor, said: “Our most successful customers enjoy investing and looking after their portfolio, so will buy and sell investments when they spot an opportunity.
“What unites them is diversification, spreading their investments across different assets, markets and sectors to ensure that all their eggs are not in one basket.
"The importance of diversification is true to every saver – whether or not you have a seven-figured pension pot."
But she warned that millionaire Sipp holders were at risk of breaching the pension lifetime allowance which stands at £1,055,000.
Ms O’Neill added: “While the prospect of becoming a Sipp millionaire is a lovely one, the one big danger with saving more than a million pounds in your pension is that you could potentially breach the lifetime allowance - and punitive tax applies if you do.
“Some of our Sipp millionaires were able to take advantage of pension protections that were available in the past, so have higher lifetime limits.
“For those investors who don’t have the same luxury now, you need to be mindful of how much to put into your pension and whether other tax advantageous options, such as venture capitalist trusts or Isas, might be a good alternative.”
Last month (October 28), Embark agreed to buy the adviser platform business of Alliance Trust Savings from Interactive Investor, effectively carving out this element of the platform business from the D2C one.