The number of Barclays Stockbrokers client ISA accounts using ETFs has increased 40% since January 2010 and 91% over the past two years.
The stockbroker says nearly a half of its clients' ETF holdings are in ISAs and over a tenth are in self-invested personal pension (SIPP) accounts, which have seen ETF usage increase 45% year-on-year.
Barclays says the figures show investors making the most of their tax allowances, as both ISAs and SIPPs allow tax free use of ETFs.
As the uptake of ETFs grows, the stockbroker's clients are showing a taste for diversifying their portfolios, including increasing exposure to emerging markets
The most common ETF within an ISA remains the iShares FTSE 100, but the iShares MSCI Emerging Markets has grown in popularity more than any fund, with holdings rocketing 43% over 2010.
The iShares S&P 500 saw its usage go up 27%, making it the second most improved ETF.
Barclays Stockbrokers head of product Paul Inkster says: "Although clients trade frequently in the main UK markets, there is a clear trend towards using ETFs to gain international exposure, especially in emerging markets."
He adds: "The practicality of a single investment is favoured over the process of researching and investing in individual stocks, which can be difficult, time consuming and costly."
Barclays Stockbrokers clients also chose 2010 to seek exposure to gold through ETFs in their ISA accounts. ETFS Physical Gold now makes up 3% of ISA ETF holdings and is the ninth most popular ETF, despite having not featured in the top ten funds this time last year.
Inkster says ETFs are being used both to capture short-term market movements as well as in longer term portfolio construction.
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