Radiohead's fractured, disassembled opening to Kid A captured something in 2000 that portfolio managers are only now being forced to reckon with: when the familiar order dissolves, the answer isn't retreat — it's reordering. Acadian Asset Management's April 2026 research brief makes exactly that argument, and makes it with fifty years of data behind it.
The world Radiohead sang into in 2000 was already beginning to crack at its seams — the dot-com bubble inflating toward its inevitable rupture, geopolitical certainties quietly fraying beneath a surface of apparent prosperity. The song offered no comfort, only a strange, insistent logic: everything in its right place. Not everything is fine. Not everything is safe. But everything, properly arranged, has a place in the structure.
That is, almost precisely, the investment thesis Acadian Asset Management advances in Putting Portfolios Together when the World is Falling Apart1, published April 2026. The world is fragmenting. Markets are decorrelating. And the rational, mathematically grounded response is not to consolidate — it is to diversify more broadly than ever.
The Correlation That Globalization Built
For five decades, the architecture of the global economy expressed itself in the statistical convergence of equity markets. Acadian's dataset covers average pairwise correlations across the 23 developed market countries currently in the MSCI World Index, calculated using rolling 60-month windows of gross USD returns from January 1970 to March 2026.
The trend is unambiguous. Average DM cross-country correlation rose from 0.39 in the period 1970–1997 to 0.65 in the period 1998–2026. The U.S.–Germany bilateral correlation tells the same story in sharper relief: 0.35 before 1998, 0.81 after. Acadian frames this shift as the direct statistical consequence of globalization — falling trade barriers, capital account liberalization, the fall of the Berlin Wall (1989), NAFTA (1994), China's WTO accession (2001), and EU expansion through the 2000s.
Research cited in the paper reinforces the long historical arc. Goetzmann, Li, and Rouwenhorst (2005), examining global stock returns from 1850 to 2000, found that "correlations vary considerably over time and are highest during periods of economic and financial integration such as the late 19th and 20th centuries." The current era is not anomalous — it is historically legible.
When the Order Dissolves
Globalization's momentum began breaking down after the Global Financial Crisis. The Brexit vote (June 2016), Russia's full-scale invasion of Ukraine (February 2022), and the tariff announcements of the Trump administration (April 2025) each marked a further step back from integration. Whether this constitutes true deglobalization or merely what the literature terms "slowbalization" remains contested — but Acadian's analytical framework does not require certainty on that question.
This is where the Radiohead parallel cuts deepest. Everything in Its Right Place is not a song about order restored — it is a song about order dissolved and then reconstructed on different terms. The familiar has been taken apart. The question is not how to put it back together the old way. The question is how to arrange what remains into something that holds.
Acadian's answer is the same: when the old correlation regime dissolves, the investor's job is not to retreat into the familiar. It is to reconstruct the portfolio on the new terms that fragmentation actually offers — lower correlations, higher diversification benefit, broader protection.
The Diversification Dividend of Decorrelation
The paper's central insight is that as cross-country correlations fall, the mathematical benefit of global diversification rises. Acadian defines the diversification benefit as the reduction in portfolio volatility achieved by holding a diversified portfolio instead of a single country.
Under the lower-correlation pre-1998 regime, the MSCI World portfolio delivered a volatility of 14% — 37% lower than the 22% average volatility of its constituent countries. After 1998, with correlations elevated, that benefit compressed to 28%. The drawdown data reinforces the point: diversification reduced maximum drawdowns by 22% before 1998, compared to 14% afterward — a 1.6x advantage for the earlier, lower-correlation period.
The paper's conclusion is stated without hedging: "While the free lunch of global diversification is always valuable, it becomes especially nutritious when markets fragment and correlations decline."
In other words — when the world stops moving as one, each country finds its own place in the structure. And that separation, properly captured in a globally diversified portfolio, is exactly what protects.
The U.S. Exceptionalism Trap
One of the paper's most important contributions is its systematic dismantling of the case for U.S.-only equity portfolios. Post-1998 data, viewed in isolation, appears to validate the home-bias thesis: U.S. equities recorded a maximum drawdown of 51% versus 54% for the MSCI World, with similar volatility.
But Acadian identifies this as precisely the kind of reasoning that trailing performance makes seductive and future positioning makes dangerous. Before 1998, the U.S. had drawdowns and volatility that exceeded those of the world index. Germany, which had the mildest pre-1998 drawdown at -36%, deteriorated to -64% after 1998 — worse than the average DM country and worse than the global benchmark.
The regime reversal is stark. "Trailing performance can be a misleading guide to the future," the paper states. "It is not a law of nature that the U.S. always has lower risk than the world index."
The Radiohead frame applies here with particular force. The investor who looks at post-1998 U.S. performance and concludes the arrangement is permanent is listening to the old album expecting the same sounds. The world has already moved to Kid A. The sonic landscape has changed. The old map no longer describes the territory.
Uncertainty Is the Argument for Breadth
Acadian extends its argument beyond equities to the broader uncertainty landscape — including, notably, artificial intelligence. Which nations will be the winners of deglobalization? Which will capture the AI dividend? The firm's answer is explicit: nobody knows. And not knowing is itself the definitive case for holding everything.
"Which countries will be the winners? We don't know. The appropriate response, therefore, is to diversify across countries."
Currency exposure follows the same logic. Deglobalization introduces the possibility of dollar instability and exchange rate dislocation. A world portfolio spreads currency risk structurally — a hedge that a U.S.-only allocation simply cannot replicate.
The paper closes on a note that could serve as the investment world's equivalent of Thom Yorke's mantra: "If you want to minimize risk, then you should diversify more — not less — when markets decorrelate." Everything in its right place. Not concentrated. Not retreated. Arranged — deliberately, broadly, and with clear eyes — across the full map of what the world still offers.
Five Key Takeaways for Advisors and Investors
1. Deglobalization is a diversification signal, not a retreat signal.
As cross-country equity correlations fall, the mathematical benefit of holding a globally diversified portfolio increases. The instinct to home-bias in uncertain times is precisely backwards.
2. The pre-1998 template is the relevant benchmark.
If the world returns to pre-1998 correlation levels (average DM pairwise correlation of 0.39), the volatility reduction benefit of global diversification could be nearly twice what it was in the high-correlation post-1998 era.
3. U.S. outperformance is a data artefact, not a structural guarantee.
The post-1998 record of U.S. equity superiority reflects a specific regime. Before 1998, the U.S. had higher drawdowns and greater volatility than the world index. Country rankings rotate — and the rotation is unpredictable.
4. Currency diversification matters as much as equity diversification.
Dollar dominance is not guaranteed in a deglobalizing world. A world portfolio provides structural currency exposure breadth that a concentrated domestic allocation cannot replicate.
5. Uncertainty about winners is itself the case for breadth.
Neither deglobalization nor AI disruption comes with a map identifying the beneficiary nations. The risk-minimizing portfolio is the one that doesn't bet on knowing the answer — it holds all countries, puts everything in its right place, and lets diversification do the work.
Footnotes:
1 Acadian Asset Management. "Putting Portfolios Together when the World is Falling Apart." Acadian Asset Management, Apr. 2026, acadian-asset.com.
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