Diversification Had Its Best Year Since 2009. Here's What Drove It.

The year 2025 was a watershed moment for investors who stayed diversified. The persistent narrative that diversification is dead took a substantial hit when a broadly diversified portfolio outpaced a plain-vanilla 60/40 allocation by 5 percentage points. This represented the widest margin of outperformance since 2009.  

But what drove that gap, and what does it mean for how advisors should think about portfolio management going forward? 

This article draws on the Morningstar 2026 Diversification Landscape report to highlight key takeaways. We'll cover everything from fixed income and real assets to alternatives and inflation protection, providing actionable insights for your investment portfolio construction. 

In 2025, our broadly diversified test portfolio returned 18.3%, compared with a 13.3% return for a standard 60/40 portfolio consisting of US stocks and US investment-grade bonds. 

Several factors contributed to this outperformance. 

• A surge in gold: Gold climbed 67.4%, reinforcing its role as one of the most effective commodity diversifiers. 
• Stronger performance from non-US assets: International stocks outpaced US equities by a wide margin, benefiting from a weaker US dollar and relatively lower starting valuations.
• Lower correlations: Many asset classes moved less in lockstep, improving the effectiveness of diversification, particularly during periods of market stress such as tariff-related volatility earlier in the year.

There is an important caveat for long-term portfolio management. Over most trailing 10- and 20-year periods, the standard 60/40 allocation still led on risk-adjusted returns. However, 2025 proved that when broader asset classes align favorably, the stock market does not have to be the sole driver of growth. 

The standard mix of US stocks and investment-grade bonds remains formidable.  

Over most trailing periods in the past two decades, a basic mix of US stocks and high-quality bonds outperformed more broadly diversified portfolios. The standard 60/40 also delivered stronger risk-adjusted returns in every rolling 10-year period since early 2005. 

The strategy provides a reliable way to protect against loss and manage investment risk over long horizons. 

However, the landscape is shifting. Correlations between US and non-US stocks are trending lower, reflecting a weaker dollar and increasing fragmentation in global trade. This divergence may be opening a new window for broader diversification strategies.  

Additionally, the stock and bond correlation returned to negative territory in 2025 after displaying elevated, positive readings from 2022 through 2024. 

The takeaway for advisors is straightforward. You do not necessarily need to move clients too far beyond large-cap stocks and high-quality bonds to build effective portfolios. But targeted additions, particularly in environments like 2025, can improve outcomes at the margin. 

We are seeing new trends in recent years. Correlations between the US and developed international markets have trended lower since 2022 as the dollar weakened and global trade fragmented.  

For effective portfolio management, patience is essential. Rolling three-year correlations eventually reset, even after painful rate pivots. By staying the course, advisors can help clients realize the long-term mathematical benefits of holding uncorrelated assets. Good investment decisions require looking past short-term regime changes to protect against loss over the long run. 

Stocks and bonds tend to move more in tandem during inflationary periods, but bonds can still provide significant diversification benefits and play a critical role in providing ballast and reducing risk. 

These asset classes have historically been valuable hedges against inflation risk. 

• Commodities have historically excelled during high-inflation periods, particularly gold and oil. Gold maintained a near-zero correlation to equities. This makes it one of the most reliable alternative investment options for navigating turbulent markets.
• Treasury Inflation-Protected Securities, or TIPS, offer direct inflation hedging. They are especially useful when real yields are positive. 
• Cash remained one of the most reliable diversifiers during recent rate-hike cycles, providing liquidity and stability without taking on additional risk. 

By contrast, both stocks and core bonds have struggled during sustained inflation.  

Higher inflation typically makes for a more challenging environment for stocks, as it leads to higher operating costs in the form of raw materials, components, wages, and other expenses. 

Higher inflation can also make conditions challenging on the fixed-income side, but the impact is usually less direct. A surge in inflation often prompts the Federal Reserve to hike interest rates, which reduces bond prices and leads to tighter comovement between stocks and bonds. 

Across other asset classes, both developed- and emerging-market stocks have typically fared the worst during periods of high inflation, partly because such periods often lead to interest rate hikes that strengthen the US dollar. A stronger dollar, in turn, means lower returns on non-US assets when translated back into dollars, as well as a heavier burden for emerging markets with dollar-denominated debt. 

REITs have also performed poorly in most inflationary periods, despite their often-touted ability to raise rents as inflation rises. 

Adding real assets to an investment portfolio can be highly effective for reducing risk, provided allocations are sized correctly.  

By year-end 2025, the three-year correlation between commodities and US stocks dropped to just 0.05.  

• Industrial metals led the charge, with copper surging 38.7 percent, driven by demand for electrification and artificial intelligence infrastructure.
• Real estate investment trusts have historically shown correlations of around 0.70 with the broad market. They are useful for generating yield but are less reliable for pure diversification. 
• Office subsectors remain under pressure despite falling interest rates. 

The dispersion of commodity returns in any given year is wide; wealth management professionals must approach sizing and implementation with care, perhaps using targeted index funds. 

Alternative strategies are fundamentally designed to reduce drawdowns rather than maximize returns in bull markets. For example, equity market-neutral strategies showed a negative correlation of 0.18 with US stocks in 2025 over the past 3 years.  

• Systematic trend strategies posted a negative 0.04 correlation but underperformed in the fragmented, policy-driven market of 2025.
• Private equity and venture capital share much of the same risk profile as small-cap equities. They act as an alternative investment but introduce liquidity challenges and higher risks. 
• Semiliquid private fund structures showed visible stress in 2025. Liquidity risk is real and frequently underpriced by many investors. 
• Private credit, real assets, and real estate have lower long-term correlations; infrequent pricing can mask their true volatility. 

Financial advisors looking to protect against loss must carefully weigh these structural investment risk factors. 

For clients with an appetite for higher risk, specific assets offer distinct growth avenues. Cryptocurrency has delivered more than 150% annualized returns since 2010, the highest of any major asset class.  

• Bitcoin's three-year correlation with US stocks is now 0.49, up dramatically from near zero just a few years ago. 
• Crypto's extreme volatility means even a small allocation can have an outsized impact on the overall risk of an investment portfolio.
• Small-cap value and international value stocks have also provided meaningful investment strategies to diversify away from US large-cap growth concentrations.

For growth-oriented investors looking beyond the US stock market, emerging-market equities offer lower correlations and exposure to different economic cycles.  

Applying these insights to wealth management requires a structured approach.  

For most investors, a diversified mix of US large-cap stocks and high-quality bonds remains the core of sound portfolio management. 

• Cash and short-term bonds deserve a permanent place in drawdown portfolios, especially for retirees navigating rising-rate environments. 
• Gold has clearly earned its role as a reliable safe-haven allocation, while commodities broadly require more care and context due to extreme performance dispersion.
• International exposure can significantly improve diversification as US and global correlations drift lower. Emerging markets and non-US value stocks offer compelling risk-adjusted profiles. 
• Private investments and crypto may add breadth to an investment portfolio, but they come with structural risks that warrant careful due diligence from every financial advisor.

The 2025 data reminded investors why diversification still matters. The macroeconomic environment has shifted in ways that may sustain diversification benefits for longer. 

No strategy works perfectly in every regime. The historical tendency for correlations to rise during stress periods serves as a standing caution. The best approach remains intentional, well-researched, and built for the long term. 

To explore the underlying data and find the best vehicles for your clients, read the full Morningstar 2026 Diversification Landscape report and access our comprehensive fund research resources today. 

Advisors can leverage Morningstar's fund research tools in the Direct Advisory Suite to evaluate specific strategies on yield, growth, and expense ratios.