Some increase my exposure to smaller companies. Others deliberately tilt towards the UK, income-producing shares or parts of Asia that receive relatively little weight in a conventional global index.

But one investment sits above them all.

The Vanguard FTSE Developed World UCITS ETF — better known by its London Stock Exchange ticker, VHVG — accounts for 40% of my ISA.

That is not an accidental allocation. It is the central workhorse of the portfolio: the holding I expect to provide most of its long-term growth while the remaining funds make smaller, deliberate adjustments around it.

VHVG tracks the FTSE Developed Index, which contains large and medium-sized companies across developed stock markets.

As of 30 June 2026, the ETF held approximately 1,977 companies. Around 68.6% of the portfolio was invested in the United States, followed by Japan at 6.6%, the UK at 3.5%, Canada and South Korea at 3.2% each, with further exposure across Europe and the developed Asia-Pacific region.

Its largest holdings included Nvidia, Apple, Alphabet, Microsoft, Amazon and Broadcom. However, buying VHVG is not simply a bet on a handful of American technology companies.

The fund also owns banks, industrial businesses, healthcare companies, consumer brands, energy producers, utilities and property companies across many different countries. Technology was its largest sector at 34.9%, but financials, industrials, consumer discretionary and healthcare together represented a substantial part of the portfolio.

That breadth is the first reason I like it.

With a single purchase, I gain ownership in nearly 2,000 businesses operating across the most established stock markets in the world.

It would be easy to look at the recent dominance of the United States and conclude that an S&P 500 tracker is all an investor needs.

I understand the attraction. American companies have produced extraordinary returns, and the US remains the world’s largest and most innovative stock market. But I do not know whether it will remain the best-performing market for the next 10, 20 or 30 years.

VHVG already gives me substantial US exposure because the index is weighted according to market capitalisation. When American companies grow and become more valuable, their weight in the fund rises. When companies elsewhere become more important, the index gradually adjusts.

I do not need to predict which country will dominate next. The fund follows the market. That is an important distinction. I am not avoiding America. I simply do not want my entire core portfolio dependent upon it.

The ETF has an ongoing charge of just 0.12% a year.

That means approximately £12 annually for every £10,000 invested, excluding platform fees and trading costs. Vanguard uses physical replication, purchasing a representative sample of the shares contained in the underlying index rather than attempting to manufacture the return through a synthetic contract.

VHVG is also an accumulation ETF.

The dividends paid by its underlying companies are retained and reinvested inside the fund rather than distributed to me as cash. Vanguard reported an underlying equity yield of around 1.5% as of June 2026. Those dividends may appear modest, but their reinvestment becomes increasingly powerful over long periods.

I am still building wealth rather than drawing an income, so this suits me perfectly. I do not need to decide where to reinvest each dividend or risk leaving cash sitting idle. The fund quietly does the work for me.

The size of an allocation should reflect the importance of the job it performs. VHVG receives 40% because it is the part of my ISA that requires the fewest assumptions.

I do not need small companies to outperform large ones. I do not need UK shares to experience a dramatic revaluation. I do not need a particular region, investment style or sector to lead the market.

I simply need profitable companies across the developed world to continue growing their earnings over the long term.

The other funds in my ISA are not there because I believe VHVG is inadequate. They are there because I want to introduce controlled differences around the core.

VHVG is the foundation holding that connects everything together.

No fund will ever be flawless.

Despite the word “World” in its name, VHVG does not include emerging markets. Investors will not receive direct exposure to markets such as China, India, Taiwan or Brazil through this ETF alone.

It also excludes small-cap companies, concentrating instead on large and medium-sized businesses.

The fund is heavily influenced by the United States and by a relatively small group of enormous technology companies. Its top ten holdings represented approximately 25.9% of its assets in June 2026, while the underlying portfolio traded at around 24.2 times earnings.

That is genuine concentration risk.

But I do not believe the answer is to abandon market-capitalisation weighting or attempt to guess which major companies are about to underperform.

My answer is to recognise the weakness and diversify elsewhere.

VHVG will never be the most exciting investment I own.

It will not produce the thrill of identifying an overlooked company before the wider market discovers it. It does not promise spectacular returns from a fashionable theme, emerging technology or single country.

That is precisely why I trust it with the largest allocation in my ISA.

Its job is not to be exciting. Its job is to give me low-cost ownership of nearly 2,000 established businesses, reinvest their dividends and allow the most successful companies to become progressively more important within the fund.

I can adjust the edges of my portfolio. I can increase my exposure to smaller companies, the UK or Asia. I can hold alternatives alongside it and rebalance using new contributions.

But at the centre, I want something broad, inexpensive and difficult to outthink.

For me, VHVG is not merely another fund in the portfolio.

It is the core engine room.

The Compounder
Long-term investing made simple.

The Compounder is for financial education and commentary only. I am not authorised or regulated by the Financial Conduct Authority and I do not provide financial advice, investment advice, or personal recommendations. Nothing published here should be taken as a recommendation to buy, sell, hold or switch any investment, fund, pension, ISA, crypto asset or financial product. Always do your own research and consider speaking to an FCA-authorised financial adviser if you are unsure.