A critique of the claim that passive investing is a bubble

If only one person does this I can call him names and downvote him. If there are two camps and both camps do this, people tribalize and everything goes meta. Then no further actual discussion can take place.

If you're talking about index mutual funds, then the author is just plain wrong. Any open-ended fund offering daily liquidity will trade, and therefore produce market impact, to meet its daily redemptions.

If you're only talking about ETFs, then this is technically correct. Besides the occasional index re-constitution, unlevered index ETFs don't do any trading. However it's definitely not true that there's no market impact. As the fund grows (or shrinks) the shares just don't magically appear in the portfolio. Somebody has to go out and buy (or sell) those shares, and like any trading volume, that creates market impact.

The mechanism that ETFs actually use is something called "Authorized Participants" (or APs for short). Basically market makers have the right to create or redeem shares in the ETF. To create new shares, they go out and buy all the stocks in the index, then hand a basket over to the ETF fund manager, who then hands back new shares of the equivalent value. And to destroy shares, the AP hand over shares in the ETF, and the fund manager hands back a basket of shares from the index.

If there's high demand for investors to own the ETF, that'll push up the ETF's stock price. As the price rises relative to the index value, APs will detect an arbitrage opportunity. They'll go out and buy the basket of stocks in the index at a cheaper price, then create new ETF shares at the richer price, and pocket the difference. Vice versa if there's demand from investors to exit the ETF.

The mechanism keeps the ETF price closely pegged to the index, because the further out of line it gets the more arbitrageur activity pushes it back in line. While also flexibly satisfying investors' specific demand for the ETF at any given time. Basically it delegates the role of trading from the fund manager, who usually doesn't have any special expertise in trading, to highly specialized trading firms and market makers.

However, as you can clearly see, market impact most definitely exists. If a flurry of investors rush to enter or exit an ETF, then a huge amount of trading has to be done to create or redeem the shares. Just because the APs create this trading impact, instead of the fund itself, is a distinction without a difference. The underlying stocks in the index are subject to market impact.

Active funds literally own the market. When you buy an index fund of the total stock market, you are literally buying the stock market in proportion to the shares held by all active investors. If you sum up the collective holdings of active managers, what you basically get is a market-cap-weighted index. Index fund investors are simply buying what the active investors have laid out for them.

I don't have the knowledge to evaluate this statement, but to me, it undermines Burry's point that passive investing distorts prices.

And this bit that he quotes from someone else expands on the point:

The use of price signals by those who played no role in setting them may be capitalism’s most important feature. That most of us and most of our dollars don’t have to pick stocks, or to price air conditioners, is a great benefit and taking advantage of it makes us honest smart capitalists, not commissars.

As I understand it, Burry's argument is that index funds distort prices because capital is being allocated in an automated and uniform way, instead of being allocated according to the expertise of a diverse, success-weighted group of investors who are motivated to make intelligent and informed decisions. At some point the difference between the index-fund-driven prices and the "true" prices according to informed opinion will become obvious, and investors will attempt to flee index funds, popping the bubble. The rebuttal in this argument is that active investors are still controlling the market because index funds mirror their activity. We will never reach a state where people will rush to "escape" from the index funds to actively managed funds, because index funds will always approximate the aggregate opinion of the actively managed funds.

This accords with my naive idea of how index funds work, but I don't know if they actually do work that way, so I can't evaluate the soundness of either argument.