# The Inelastic Market Hypothesis: A Microstructural Interpretation

**Authors:** Jean-Philippe Bouchaud  
**arXiv:** [2108.00242](https://arxiv.org/abs/2108.00242)  
**Date:** 2021-07-31  
**Summary page:** https://www.summarizepaper.com/en/paper/2108.00242v5/

## Key points

- The paper aims to reconcile the Inelastic Market Hypothesis (IMH) with the order-driven view of markets
- Market price fluctuations are primarily influenced by order flow, whether it is informed or non-informed
- The Latent Liquidity Theory predicts GK's multiplier $M, which measures how much a company's market value increases when one dollar worth of its stocks is purchased
- The study finds that $M is approximately equal to unity, as previously observed by Gabaix and Koijen
- $M increases with stock volatility and decreases with the fraction of daily traded market capitalization
- Trading activity plays a significant role in driving market volatility
- Order flow predominantly contributes to price fluctuations in various asset classes beyond just stock markets

## Summary

In the paper titled "The Inelastic Market Hypothesis: A Microstructural Interpretation," Jean-Philippe Bouchaud aims to reconcile Gabaix and Koijen's recent Inelastic Market Hypothesis (IMH) with the order-driven view of markets that has emerged within the microstructure literature over the past two decades. The author reviews empirical evidence and arguments that support the idea that market price fluctuations are primarily influenced by order flow, whether it is informed or non-informed. One key aspect discussed in the paper is the Latent Liquidity Theory of price impact, which provides a precise prediction for GK's multiplier $M. This multiplier measures how much the market value of a company increases on average when one dollar worth of its stocks is purchased. The central finding of this study is that $M is approximately equal to unity, as previously observed by Gabaix and Koijen. Furthermore, it is shown that $M increases with stock volatility and decreases with the fraction of daily traded market capitalization. The paper also presents several empirical results suggesting that trading activity plays a significant role in driving market volatility. These findings support the notion that order flow, rather than other factors, predominantly contributes to price fluctuations in various asset classes beyond just stock markets. Overall, this study provides a microstructural interpretation of Gabaix and Koijen's Inelastic Market Hypothesis by examining empirical evidence and arguments related to order flow's influence on market prices. The findings highlight the importance of trading activity in understanding market dynamics across different asset classes.