Index bubble


This passive investing/index bubble idea from a Michael Burry interview continues to circulate. The idea has appeal, not the idea that another recession is imminent, but the idea that we could accurately predict one coming, and that the cause could actually make sense to us. The argument is fairly simple. A larger percentage of people are buying index funds, especially the S&P 500, than ever before. Index fund investors tend not to analyze each company in the S&P 500, they simply buy the index which owns all of them. So Burry worries that since fewer and fewer people are conducting analysis on company fundamentals, the prices of these companies are going to be inflated by virtue of the simple fact that they’re included in an index, not because they’re good companies that people believe in. That makes sense. The question then, is how much analysis and trading do we need in order to maintain a decent level of price discovery in the market? If index funds stifle price discovery, how do we avoid a bubble? Here are a few responses:

  • Even a small amount of price discovery (studying fundamentals, making trades, supply and demand) makes a huge difference for prices to reflect value. We don’t need large swaths of the market conducting analysis.
  • If 100% of invested assets were in index funds the price discovery argument might hold some weight. You would have to assume that there would be almost no company fundamental analysis happening, not an unreasonable jump but still an assumption. However, the truth is that only about 45% of invested assets are in index funds, and there’s still a host of investors and dollars outside of passive index funds working to set prices.
  • Index investing actually adds data to the market, it contributes to price discovery. Instead of contributing data on specific stocks, it contributes to larger market sector data as people commit dollars to different indexes across the world, which is helpful market data.
  • Despite the growth of index fund investing, global stock trading volume has actually remained about the same over the last ten years. People use passive vehicles to actively trade. Many index fund dollars are in ETFs among the most traded funds on the market. Just because money is in index funds does not mean that it’s passive. The activity all contributes to price discovery.
  • Some passive investors (like us!) actually do use some fundamental analysis in constructing portfolios (structured funds). And even our passive investors occasionally make trades; in order to rebalance, when they make contributions or withdrawals, etc. Even the most passive investors contribute to price discovery.
  • If the market was losing efficiency and price discovery as a result of growing index fund investors, we would expect to see an uptick in active money manager performance. Active managers would find the mispriced companies in the index and reap corresponding rewards. But the data shows no improvement, active managers have performed slightly worse over the last three years than before.

Despite the uptick in index and passive investing, price discovery is as strong as it ever has been in the stock market. Michael Burry’s comments on the index bubble are interesting and even sound plausible, but upon close inspection look misguided. Passive investing is still the way to go, though you do have permission to dump those index funds.

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