Holding a wide variety of assets can significantly reduce the risk of investment losses by ensuring no single holding is substantial enough to damage overall returns. Taking a balanced approach to investing creates less portfolio volatility because poorly performing assets are generally offset by others that perform better. Spreading capital requires allocating across asset classes, including stocks, corporate bonds, government bonds, property, and commodities such as gold.
Investors also need to spread investments geographically and across market types, including developed, emerging, and frontier markets. While multi-asset funds or global trackers perform much of this diversification work, global trackers risk inadvertently over-exposing portfolios to US technology giants. Investors moving into specialist or actively managed funds must monitor natural biases toward investing styles such as value, growth, or quality, which dominate at different times.
Tax rules, incentives, and drawbacks vary across investment vehicles and can be altered by the government. Modern workplace pensions offer cheap, heavily subsidised options, with default funds providing a basic, no-hassle route. However, pension funds remain locked until age 55, or 57 from spring 2028, and post-lump-sum withdrawals are taxed as income. Financial analysts recommend building an emergency fund in a cash ISA before opening a stocks and shares ISA, where post-tax contributions grow tax-free and remain accessible at any age.
Expert rules for portfolio diversification
Rob Morgan, chief analyst at Charles Stanley Direct, said: "Spreading your money over different investment leads to a less bumpy ride as various investments perform differently rather than moving mostly in tandem." He added: "No single area can be on top forever, which is why it’s important to hold a mixture. If you hold too few or too similar investments, things can work well for a while but can also quickly go downhill."
James Scott-Hopkins, founder of wealth manager EXE Capital Management, warned against over-diversifying. "There is diversification and over-diversification," Scott-Hopkins said. "Diversification is key to reducing volatility but overdoing it will likely mean poorer returns. Like a good diet, everything in moderation." He added: "Too much, and you end up reverting to the mean, so you might as well buy a tracker fund. But, as we know, we have the problem of concentration risk, with nearly half the S&P 500 in AI-related businesses."
Darius McDermott, managing director at FundCalibre, cautioned that extreme market sell-offs can undermine diversification. "Diversification is often described as not putting all your eggs in one basket," McDermott said. "But that's only half the story - if every basket sits on the same cart, it doesn't matter how many you have; one pothole and they all bounce the same way."
Portfolio review warning signs and allocation guidelines
Investors should align diversification with their investment goals, time horizon, and risk tolerance. Morgan explained that taking on too little risk in your 20s and 30s can be a wasted opportunity. However, allowing investments to remain overly concentrated later in life exposes investors to volatility when drawing an income. Longer time horizons justify higher share allocations, including exclusive equity portfolios for retirement decades away.
Morgan identified three main warning signs indicating a portfolio review is required: high value volatility with big ups and downs, holding only a small number of individual shares or specialist funds rather than broad trackers, or having assets that move in tandem at the same time.
When structuring a portfolio, Morgan suggested a balanced benchmark of 60 to 80 per cent exposure to shares and 20 to 40 per cent to bonds and other dampening assets. Portfolios of individual shares require 30 to 40 holdings alongside active monitoring, whereas 10 to 20 funds provide appropriate breadth. Morgan warned against creating a "stamp collection" of unstructured holdings, advising investors to start with overall strategy and populate each area with one or two funds.
Fund recommendations and manager strategies
Scott-Hopkins recommended compiling funds from conviction managers focused on three core themes: momentum in artificial intelligence, companies with strong competitive moats, and businesses with robust cash flow and pricing power to counter inflation.
Scott-Hopkins highlighted the Polar Capital Global Insurance fund, managed by the same manager for 25 years with average annual growth of 10 per cent, noting its negative correlation to equities during bear markets. He also tipped the nearly 100-year-old Brunner Investment Trust, which holds roughly 50 stocks worldwide to deliver broad revenue diversification.
McDermott offered specific fund ideas across key asset classes:
- Strategic bonds: GAM Star Credit Opportunities and Invesco Tactical Bond provide flexible access across fixed income.
- Absolute return: BlackRock European Absolute Alpha uses long and short positions to deliver positive returns regardless of market direction.
- Real assets: Cohen & Steers Diversified Real Assets and First Sentier Global Listed Infrastructure offer ballast from toll roads, utilities, and infrastructure.
- Growth, value, and quality: Ranmore Global Equity buys cheap value shares below market averages with an income, while IFSL Evenlode Global Equity backs quality growth names such as Mastercard and Visa.
- Multi-asset: Jupiter Merlin Balanced Portfolio holds 40 to 85 per cent in equities alongside bonds in a single package.
Global tracker risks and index concentration
Passive global tracker funds provide low-cost market access, but analysts warned they involve heavy concentration bets on US markets, which represent roughly two-thirds of global equity indices. Funds such as Fidelity Index World or iShares Core MSCI World UCITS ETF provide access to thousands of companies worldwide, but remain heavily skewed toward large US tech firms.
Jason Hollands, managing director of Bestinvest, stated: "The traditional assumption that investing in an index tracker automatically delivers broad diversification deserves renewed scrutiny."
Hollands noted that the Magnificent Seven - Nvidia, Microsoft, Apple, Alphabet, Amazon, Meta, and Tesla - account for one third of the S&P 500 Index. Adding semiconductor manufacturers Broadcom and Micron Technology brings the top ten stocks to 37.4 per cent of the entire index.
The artificial intelligence boom is also reshaping regional indices. The MSCI Emerging Markets Index holds close to 30 per cent exposure to three semiconductor companies: Taiwan Semiconductor Manufacturing Company (TSMC), Samsung Electronics, and SK Hynix. Consequently, Taiwan and South Korea have become the two largest country positions, pushing China down from around 43 per cent in 2020 to 18.9 per cent, with India in fourth place. Hollands warned that emerging market tracker buyers are inadvertently making major bets on semiconductor manufacturers and the AI cycle.
Alternative diversification strategies and equal weight funds
To mitigate concentration risk, Hollands suggested equal-weighted funds, which allocate equal weight to each company in an index. For US exposure, investors can combine a standard tracker with the Legal & General S&P 500 Equal Weight Index fund. Alongside a global tracker, investors can add the Invesco MSCI World Equal Weight UCITS Exchange Traded Fund.
Morgan noted that equal-weight strategies tilt toward cheaper value stocks in industrials, real estate, materials, and utilities. The Xtrackers S&P 500 Equal Weight UCITS ETF weights components equally at approximately 0.2 per cent and rebalances quarterly.
For defensive global equities, Morgan highlighted JO Hambro Global Opportunities, which maintains zero exposure to Nvidia, Apple, Amazon, Meta, Broadcom, and TSMC, as well as Trojan Global Income, which focuses on predictable businesses compounding earnings over time.
Hollands also recommended factor funds, such as the Invesco RAFI US Fundamental Value ETF. Holding the 1,000 largest US companies, it weights holdings based on five-year average sales, five-year average cash flow, book value at review date, and five-year average dividend distributions.
Four practical steps to diversify investments
McDermott outlined a four-step quick guide for investors looking to diversify:
- Do not rely purely on equities.
- Within equities, spread exposure further and avoid buying only recent winning trends.
- Check in regularly for a portfolio MOT every six to 12 months, using both ISAs and workplace pensions to optimise tax efficiency.
- If managing a portfolio is too complex, opt for a ready-made multi-asset fund.
