Building a Global Investment Portfolio: A Framework for International Investors

For most UK-based investors, portfolio construction means choosing a mix of UK equity funds, global trackers and some bonds. For internationally mobile HNW individuals — with assets, income and liabilities spanning multiple currencies and jurisdictions — the challenge is fundamentally different. The investment question and the tax and structure question cannot be separated.

This guide sets out a practical framework for constructing a global investment portfolio that is both well-diversified on the investment merits and appropriately structured for international tax efficiency.

Step 1: Establish your financial picture

Before selecting investments, map the full landscape:

Income streams: What is your employment or business income, and in which currency? What is the tax treatment in your country of residence?

Existing assets: What do you already hold, in what wrappers, in which jurisdictions? UK SIPP, ISA, offshore bond, direct equity holdings, property, cash?

Liabilities: What mortgages, loans or financial obligations do you have, and in which currencies?

Base currency: What is the currency of your essential living expenses? This drives the currency risk analysis.

Time horizon: When will you need capital — for children's education, retirement, a property purchase? Different portions of the portfolio have different time horizons.

Tax position: Where are you tax-resident? What is your marginal tax rate? Do any double taxation treaties affect your investment structuring?

This picture is the foundation. A portfolio designed without it is just an exercise in fund selection.

Step 2: Strategic asset allocation

Strategic asset allocation (SAA) is the long-term target split between major asset classes. Academic finance suggests asset allocation is the dominant driver of portfolio performance over time — far more so than individual security selection.

For a globally diversified HNW portfolio, the major asset classes typically include:

Equities (growth) — 30–60% for most growth-oriented investors. Global equity exposure should not be UK-centric: the UK market represents approximately 4% of global market capitalisation. A truly global equity allocation tracks the MSCI World or MSCI All Country World Index (ACWI), with tilts to specific regions or sectors as appropriate.

Fixed income (stability and income) — 15–40% for cautious-to-balanced investors. Government bonds provide stability and reduce portfolio drawdown in equity bear markets; corporate bonds offer additional yield for additional credit risk. Inflation-linked bonds (index-linked gilts, TIPS) provide inflation protection. Duration management is critical in a rising-rate environment.

Alternatives — 10–20% for sophisticated investors. This includes real assets (listed infrastructure, REITs), private equity (via listed PE funds or direct), hedge fund strategies and commodities. Alternatives provide diversification from traditional equity-bond correlations.

Real estate — direct or via REITs. For many HNW investors, property is already a significant portion of net worth (primary home, investment properties). The portfolio allocation to real estate should account for this existing exposure rather than adding to it reflexively.

Cash and near-cash — 5–15%. A cash buffer in the base currency covers living expenses for 12–24 months without requiring forced asset sales. This is particularly important for internationally mobile investors who may face unexpected currency or tax obligations.

Step 3: Geographic and currency diversification

Geographic diversification reduces concentration in any single country's economy, regulatory environment and political risk. A portfolio of US tech stocks and UK property, however individually well-chosen, is not diversified in the way that matters.

Currency diversification is a separate but related concept. Holding assets in multiple currencies — GBP, USD, EUR, CHF — provides a natural hedge for an internationally mobile investor whose expenses are in multiple currencies.

Practical points:

• Consider the base currency of each fund or instrument — a "global equity fund" domiciled in Luxembourg may hold USD-denominated stocks, GBP-denominated shares and EUR bonds, creating a complex currency exposure
• Currency hedged versus unhedged versions of the same fund can produce very different outcomes over 1–3 years
• For investors with long time horizons, currency movements tend to mean-revert — currency hedging may reduce short-term volatility but adds cost and complexity

Step 4: Wrappers and tax-efficient structuring

This is where portfolio construction for international investors differs most fundamentally from domestic investing.

UK SIPP — for UK pension savings. Tax relief on contributions, tax-free growth, flexible drawdown. Suitable for the retirement portion of the portfolio. Non-residents can still contribute up to £3,600 gross per year without relevant UK earnings.

Offshore bond — a unit-linked life assurance policy (Isle of Man, Ireland, Luxembourg, Channel Islands issuers). Gross roll-up: no annual tax on income or gains within the policy. The 5% annual tax-deferred withdrawal allowance provides income flexibility. Suitable for the medium-to-long-term investment portion for higher-rate taxpayers. Particularly powerful for the internationally mobile investor who plans to draw down in a lower-tax jurisdiction.

Direct investment account — a regulated investment account with a custodian. No tax wrapper, but maximum flexibility. Appropriate for assets that would trigger adverse tax treatment in a wrapper (some alternatives, certain property investments) or for investors in low-tax jurisdictions where a wrapper adds cost without proportionate benefit.

Company or holding structure — some HNW investors hold investment portfolios within a company (UK or offshore), particularly where business income already passes through a company. The interaction with personal and corporate tax rules must be carefully analysed.

The choice of wrapper is a tax decision, not just an investment decision. In many cases, the optimal structure holds different asset classes in different wrappers to minimise the overall tax drag across the portfolio.

Step 5: Rebalancing across borders

Rebalancing — selling assets that have grown above target and buying those that have fallen below — is a proven mechanism for maintaining the portfolio's risk profile and introducing a degree of contrarian discipline.

For international investors, rebalancing has additional dimensions:

• Transaction costs vary significantly by jurisdiction and asset class
• Withholding taxes on dividends and interest may differ between assets held in different jurisdictions
• CGT triggering — a rebalancing trade may trigger a taxable disposal. Rebalancing within an offshore bond or SIPP avoids this; rebalancing a direct account does not.
• Currency timing — rebalancing across currency classes may involve FX conversion costs

Rebalancing once or twice a year, with a tolerance band (e.g., rebalance if any asset class moves more than 5% from target), is a reasonable approach for most portfolios. Tax-loss harvesting — selling assets at a loss to realise a CGT loss that offsets gains elsewhere — can be incorporated into the rebalancing process.

Step 6: Drawdown planning

Building the portfolio is only half the exercise. The drawdown strategy — how, when and from where income is taken in retirement — determines the tax efficiency of the overall plan.

For internationally mobile investors, drawdown planning should consider:

• The sequence of withdrawals across different wrappers (e.g., draw taxable income first, allow offshore bond to continue rolling up)
• The impact of the annual 5% offshore bond allowance
• The State Pension commencement date and its effect on marginal tax rate
• The currency of required income versus the currency of portfolio assets
• Sequencing risk (see our dedicated article on pension drawdown)

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How Global Investments can help

We build and manage globally diversified portfolios for internationally mobile HNW clients. Our approach integrates investment strategy, tax structure and estate planning in a single coordinated service.

Contact us to discuss your portfolio strategy.

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Asset allocation ranges and portfolio principles in this article are illustrative. Investment decisions must be based on individual circumstances, risk tolerance and financial objectives. Investments can fall as well as rise in value. Past performance does not predict future results. Always obtain independent regulated advice.