IOO ETF: Can Mega-Cap Dominance Continue in a Less Accommodative Market?

The IOO ETF provides Australian investors with a concentrated way to own the world's largest multinational companies, known as global mega-caps. The fund, issued by BlackRock under its iShares brand, aims to track the performance of the S&P Global 100 Index, which comprises 100 blue-chip companies from major developed markets.

As of September 2026, IOO has grown into a multi-billion-dollar fund with around $5.9 billion in assets. The fund's holdings are dominated by the largest US technology companies, including Microsoft, Apple, Nvidia, Amazon, and Alphabet, alongside global leaders in finance, healthcare, and consumer goods.

However, the fund's performance is heavily reliant on the continued dominance of these mega-caps. With the US Federal Reserve turning more hawkish and valuations elevated, investors are questioning whether this group can maintain their leadership or if returns will broaden to a wider set of companies and regions.