Does Algorithmic Trading Improve Liquidity?
Read the paperopens doi.org in a new tab
What they found
The authors used the NYSE's staggered rollout of automated quote dissemination in 2003, which sharply increased algorithmic trading, as a natural experiment. For large-cap stocks, the increase in algorithmic trading narrowed spreads, reduced adverse selection, and made quotes more informative, while the effects were smaller and less clear for small caps. This was among the first rigorous evidence that algorithmic trading improved liquidity rather than harmed it.
What you can use
- Algorithmic trading made large-cap stocks cheaper to trade for everyone, including retail.
- The benefits were concentrated in large, liquid stocks; small caps saw less improvement.
- Narrower spreads also mean fewer easy profits for anyone trying to earn the spread manually.
Caveats
Studies one exchange's change in 2003, before HFT reached today's scale. It measures liquidity in normal conditions, not during stress events like the 2010 flash crash.
Tags: microstructure, algorithmic-trading, liquidity, hft
Summaries are our own reading of the paper, not the authors' words. Educational only, not advice. Discuss it in Book Club.