Index Overhaul Looms Over World’s Largest ETF as Tech Rally Reshapes Portfolio

The $143B iShares Core MSCI World UCITS ETF nears all-time high ahead of MSCI's semi-annual index review, driven by surging US tech stocks and record fund inflows.

The iShares Core MSCI World UCITS ETF USD (Acc) is heading into a pivotal week. On 29 May, MSCI will implement its semi-annual index review, forcing the $143 billion fund to reshuffle billions of dollars in holdings. The rebalancing comes at a time when the ETF is already riding a powerful wave: a year-to-date gain of 8.05%, a price of €120.76, and a portfolio increasingly dominated by a handful of US tech giants.

The fund closed on Friday just a shade below its recent all-time high. That near-record level caps a 30-day run of 5.06% and reflects a broad bull market that has lifted global equities. The MSCI World Index itself hit 1,117.52 points on Thursday, a new record, driven by the same technology stocks that give the iShares ETF its lopsided exposure.

Tech’s outsized footprint

US equities account for 71.91% of the index, and information technology alone makes up 27.61%. Within that, Nvidia commands more than 6% of the entire portfolio – a single-stock concentration that would have been unthinkable in a supposedly diversified world fund a few years ago. The fund’s price-to-earnings ratio has climbed to nearly 26, a rich valuation by historical standards for developed-market equities.

That tech tilt has been the engine of recent gains. Both Advanced Micro Devices and Microchip Technology signalled robust demand for data-centre chips, feeding the ongoing artificial-intelligence rally that has propelled semiconductor and platform stocks. The Nasdaq and S&P 500 also notched new highs in the same session.

Underlying strength beyond hype

While AI euphoria is a clear driver, the rally has fundamental legs. Among the roughly 1,060 companies in the MSCI World universe, aggregate quarterly earnings jumped 22% and came in about 6.3% above analyst expectations. That beat gives the advance a firmer footing than pure valuation speculation.

Global equity funds have also provided a powerful tailwind. Up to 13 May, they recorded net inflows for the eighth consecutive week – the longest such streak in months. Over that period, $39.15 billion poured into global stock funds, with the technology sector alone attracting a record $10.65 billion. These capital flows are a structural support for the ETF, which holds a broad basket of developed-market shares but is highly sensitive to sentiment around US growth stocks.

What the rebalancing changes

The index review, announced by MSCI on 12 May, will take effect after the close on 29 May, with the new weights official from 1 June. The iShares fund, which uses a sampling methodology rather than holding every constituent in exact proportion, will physically adjust its portfolio to match the changes.

Three US names are among the largest additions to the MSCI World: healthcare services provider Medline A, infrastructure company MasTec, and energy services firm TechnipFMC. In the broader MSCI ACWI, 49 stocks will be added and 101 removed. The ETF’s trading volume is expected to spike as passive managers execute the necessary rebalancing trades.

The fund’s total expense ratio stands at 0.20%. As an accumulating vehicle, it reinvests dividends rather than distributing them, which further compounds the impact of its concentrated winners. For now, the iShares Core MSCI World ETF remains a global equity proxy whose short-term fortunes are tied to the AI-heavy US market, corporate earnings momentum, and the steady inflow of new money into stock funds – all of which will be tested when the index overhaul arrives.