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How Index Investing and ETFs Affect Asset Prices and Market Quality

Article Quant Q&A · Author: finmathstudent

Summary

The document collects research leads on how index investing and ETFs may affect equilibrium prices, volatility, correlations, information production, liquidity, and corporate oversight. The motivating model has two risky assets with jointly Gaussian payoffs and two investors with different access to investments: one can hold both assets, while the other can invest only through a market-tracking ETF. The document does not solve for equilibrium prices; it offers literature to help refine that research question.

The cited papers report varied effects. Index investing is associated with lower market volatility but an uncertain effect on correlations, while other work discusses increased comovement among index constituents, shifts in liquidity, reduced information production, and possible changes in stock-price efficiency and shareholder monitoring. These findings are presented as a set of starting points and counterpoints, not as a unified conclusion. Several cited works are described as working papers or forthcoming, so their status and claims may require independent verification.

Key ideas

  • The motivating question concerns equilibrium pricing when some investors can access assets only through an ETF.
  • Research cited links index investing to possible changes in volatility, correlations, and comovement.
  • The literature also examines effects on liquidity, information production, price efficiency, and corporate oversight.
  • The reported findings vary, and some cited work is identified as preliminary or forthcoming.

Tags

Full text
# ETF pricing papers


# ETF pricing papers












May I request for research paper recommendations, if any, on existing models that study how the presence of ETFs affect equilibrium prices of the underlying assets?

I am exploring a project on a similar topic, but I would like to better understand current literature to refine the model I'm using.

The framework I'm working with is: For a $1$-period model, assume there are two assets with final payoff $S_1$ and $S_2$ that are jointly Gaussian and both have unit supply. Suppose there are two CARA investors, with total wealth $x$. The first investor invests in both assets but the second can invest only in an ETF that tracks this market. Both investors seek to maximize the expected utilities of their final wealth. What then are the equilibrium prices $p_1$ and $p_2$ of the respective assets?

Let me know if this is an appropriate site to ask this question.

Thanks for reading.

## Answer by kurtosis (score 3, accepted)

https://quant.stackexchange.com/a/57625

There are a few papers out there.

A good starting point os the (always relevant) Grossman and Stiglitz (1980) "On the Impossibility of Informationally Efficient Markets" which shows that markets cannot be perfectly efficient without analysts being rewarded for their efforts (and is mentioned by many of the following articles as explaining some of what is observed).

The paper mentioned by fesman in the comments is also excellent: Chabakauri and Rytchkov (2015) "Asset Pricing with Index Investing" shows index investing reduces market volatility but has an indeterminate effect on correlations.

Appel, Gormley, and Keim (2016) have a paper "Passive Investors, Not Passive Owners" which shows that index funds voting as a bloc leads to more oversight of firm management and changes which increase shareholder value.

He and Shi (2017) "Index portfolio and welfare analysis under heterogeneous beliefs" notes how in the presence of index investors, even investors with more accurate beliefs may benefit from switching to index investing.

Hirschleifer, Huang, and Teoh (2017) "Index Investing and Asset Pricing under Information Asymmetry and Ambiguity Aversion" shows that offering a risk-adjusted market portfolio may eliminate individual stock alphas.

Gregoire (2020) "The Rise of Passive Investing and Index-linked Comovement" shows that stocks in the S&P 500 tend to comove more with each other and less with other stocks. (This would seem to either disagree with or improve upon Chabakauri and Rytchkov's work.)

Russ Wermers has a forthcoming paper (2020?) "Active Investing and the Efficiency of Security Markets" which shows that active (and not passive, i.e. index) investing improves price efficiency.

Davidson Heath has a few which are in the working paper stage such as:

- "ETF Trading and the Bifurcation of Liquidity" (with Brogaard and Huang) which shows liquidity has been improved for index member stocks but not for other stocks;

- "On Index Investing" (with Coles and Ringgenberg) which shows index-linked investing reduces information production for individual index member stocks but that price efficiency is unchanged; and,

- "Do Index Funds Monitor?" (with Macciocchi, Michaely, and Riggenberg) which shows the rise of index investing leads to less corporate oversight if index member firms.

Since these disagree with (or add nuance to?) Appel, Gormley, and Keim (2016) and Wermers (2020?), I suspect they would make interesting counterpoints.

I could surely go on and list more (Steve Ross's APT paper, for example). however, that should be plenty to get you started.

Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.