Passive investing could increase market volatility if it grows dominant enough, as fewer active traders would mean less efficient price discovery and sharper market swings. Some analyses suggest that once the passive share reaches around 65%, index volatility may rise sharply, and at 90% share, volatility could increase at cubic speed, leading to exaggerated boom and bust cycles.
The current passive share is well below those thresholds. All funds combined make up about 30% of the US equity market, and of that 30%, roughly 54% are passive index funds, meaning passive funds account for approximately 16.2% of the total US equity market. That leaves a wide gap before reaching the proposed danger zone of 65%.
Many users argue the market has a self-correcting mechanism. If passive investing created persistent mispricings, active investing would become more profitable, pulling capital back into active management and restoring balance. Others point out that active investors, even as a small percentage, still set prices, and passive funds simply follow those trends rather than driving them independently.
Key factors
Amplified swingsAt 65% passive share, volatility may increase sharply; at 90%, cubic speed increase becomes nearly inevitable
Reduced price discoveryToo few active traders could lead to mispricings and less efficient markets
Self-correction mechanismPersistent mispricings make active investing more profitable, pulling capital back and rebalancing the market
Current market sharePassive funds are about 16.2% of US equity, far below the proposed 65% danger zone
Active sets pricesPassive investing follows active investor trends rather than independently driving price movements
Ownership concentrationA few large asset managers could eventually hold voting control over virtually every major US corporation
Potential for Increased Volatility
Amplified Swings: Some Users suggest that if passive investing, particularly through index funds, becomes too dominant, it could amplify market swings due to less active price discovery. "Once the passive share reaches around 65%, index volatility may increase sharply. At 90% share, an increase in volatility at cubic speed is nearly inevitable, leading to exaggerated boom and bust cycles."
Reduced Price Discovery: A market dominated by passive investors might lack sufficient active traders to ensure efficient price discovery, potentially leading to mispricings. "If too much investing is passive then it will increase price discovery making active investing more lucrative."
Concerns from Experts: Even prominent figures like John Bogle have expressed concern about the concentration of ownership by a few large asset managers in passive investing. "John Bogle, Wall Street Journal in Nov 2018 'If historical trends continue, a handful of giant institutional investors will one day hold voting control of virtually every large U.S. corporation.'"
Counterarguments and Mitigating Factors
Self-Correction Mechanism: Many Users believe the market has a self-correcting mechanism where increased inefficiencies from passive investing would make active investing more profitable, thus rebalancing the market. "If indexing ever created big, persistent mispricings, it would literally become easier (more profitable) for active money to correct them, which pulls capital back into active."
Current Market Share: Despite concerns, the actual share of passive funds in the US equity market is still relatively low compared to the "danger zones" proposed in some papers. "I can point out that all funds only make up 30% of the US equity market, and that 54% of the 30% are passive index funds. So 16.2% of the US equity market consists of passive funds. And the danger zone starts at 65%?"
Active vs. Passive Influence: Some argue that active investors, even a small percentage, still drive price movements and that passive investing simply follows these trends. "10 year ago NVDA was ranked 350 in the S&P and it wasn’t like passive one day decided to run it up the ranks, active still sets prices passive just latches on"
Personal Experience with Volatility
Psychological Impact: As portfolios grow, the daily fluctuations can become significant, leading to psychological effects even for long-term passive investors. "in a typical day my portfolio is up or down what I make in 1.5 months working full time How does it affect you ? Does it change your mood ?"
Ignoring Short-Term Swings: Many passive investors learn to ignore daily or short-term volatility, focusing instead on long-term growth. "I just don’t look when it’s down, and only go in when I know it’ll feel good. Then I update our spreadsheet with those higher numbers haha. I never add in the drops. Works for well being! :)"
Volatility as an Opportunity: For some, volatility can be seen as an opportunity for rebalancing or buying dips, especially within a long-term strategy. "Volatility is nothing, just temporary oscillations that in fact represent opportunities to buy dips."
Are you concerned about the long-term impact of passive investing on market stability?
Bottom line
Passive investing may increase market volatility if its dominance continues to grow, potentially leading to exaggerated boom and bust cycles. Users also debate whether passive investing actually causes volatility or if it's merely a symptom of other market forces.
FAQ
At what point does passive investing become a problem for the market?
Volatility may increase sharply when passive investing reaches around 65% of the market, and at 90% share it could rise at cubic speed. Passive funds currently sit at roughly 16.2% of the US equity market, well below those thresholds.
Does passive investing cause stock market crashes?
There is debate about this. Some users argue that passive dominance could amplify boom and bust cycles through reduced price discovery. Others counter that active investors still drive price movements and passive funds simply follow those trends.
How much of the US stock market is passive?
All funds combined make up about 30% of the US equity market, and roughly 54% of those funds are passive index funds. This puts passive funds at approximately 16.2% of the total US equity market.
Can active investing fix mispricings caused by passive funds?
Many users believe so. If passive investing creates persistent mispricings, active investing becomes more profitable, which pulls capital back into active management and naturally rebalances the market.
What did John Bogle say about passive investing concentration?
In a November 2018 Wall Street Journal piece, Bogle warned that if historical trends continue, a handful of giant institutional investors could one day hold voting control of virtually every large US corporation.
How do long-term passive investors deal with volatility?
Many choose to ignore short-term swings and focus on long-term growth. Some view volatility as a buying opportunity, using dips to rebalance or add to their positions.
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