Why it matters
It’s a sign of healthy competition and stable microstructure. When improvement disappears, market quality is degrading.
Trading use: the point is not vocabulary. The point is prediction: what changes when this shows up?
Common trap
Assuming improvement is guaranteed. In stressed regimes, improvement vanishes and slippage grows.
Example
During liquid hours, your limit order fills slightly better than your price. Around news, the same order doesn’t fill or fills worse. Market quality changed.
Operational cue: if you can’t point to it on the chart, in the DOM, or in your broker logs, treat it as a story and trade smaller.
Notes
Quick rule
- If you see this repeatedly, you are in a different regime than your model assumes.
- Regime change usually means position size change.
- When in doubt: trade smaller, or don’t trade.