Shift to Passive Investment and Its Impact on Markets
Funds that are traded on exchanges, including various passive investment options, now account for over half of the total assets in US equity funds. This trend reflects a broader shift as investors move away from actively managed options. Yet, this dominance may lead to unintended consequences, potentially altering market behavior in significant ways.
A report from Research Affiliates in June 2025 outlines that capital-weighted index funds have surpassed actively managed assets in the allocation of investors. ETF Global Insights highlighted a stark shift, noting that global net inflows into ETFs reached about $2 trillion in 2024, while actively managed funds saw an unprecedented pullback of $450 billion.
However, this migration towards more affordable and transparent investment options has sparked changes that extend beyond mere cost savings.
The benefits of passive investing have, in some ways, eroded the diverse returns that initially made these products appealing. Furthermore, it could increase systemic risks as massive amounts of capital move in sync, often overlooking the fundamental value of individual companies.
Research indicates that stocks with substantial passive ownership display a stronger correlation to general market trends, whereas those held actively tend to diverge over time. The report describes this as “adjusted price action, not informed price discovery.”
It appears that the mechanics of ETF trading exacerbate this situation. When ETFs are bought or sold, they apply pressure across numerous stocks simultaneously, irrespective of the companies’ individual circumstances.
According to passive investment research, what they term “single adjusted transactions” arise as flows increase. When investors contribute to accounts or ETFs, these funds automatically purchase stocks based largely on market cap, without factoring in company-specific details.
Data from the S&P within the study reveals that, over the past 15 years, only a third of active US equity managers have managed to outperform benchmarks. The asset-weighted average fee for passive funds stands at 0.09%, in contrast to 0.64% for active funds, which has influenced substantial reallocation towards passive options due to performance and cost efficiencies.
The report cautions that centralized ownership might create weak points prone to synchronized selling. Large institutions may systematically avoid purchases during downturns, which could diminish diversification and trigger more frequent spikes in volatility.
During the dot-com bubble, for example, cap-weighted indices led to inflated valuations in tech stocks, ultimately resulting in significant losses, as highlighted by Bloomberg data. From 1995 to 2005, the S&P 500 returned an annual average of 11.4%, while an equally weighted version provided a 13.6% return.
Researchers suggest that adopting rebalancing strategies using non-price-based anchors could help counteract distortions caused by these flows. Their analysis indicates that this alternative approach to rebalancing has historically yielded favorable returns once price corrections occur.
