Curriculum/market-impact
Market Impact
market microstructure·L1 · combinator·stub
Replacesthe belief that a 100-share order and a 100,000-share order pay the same per-share cost.
Market impact is the price move caused by a trade. Kyle 1985 derives a linear impact (lambda × signed-size) under information asymmetry. Almgren-Chriss 2000 decomposes impact into permanent (price discovery) and transient (liquidity consumption) components. The empirical *square-root law* (Bouchaud-Farmer-Lillo) is the cross-strategy regularity: impact scales with √volume, not linearly.
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- almgren-chriss-permanent-transientmodel to implementationAlmgren-Chriss splits impact into permanent (the price never returns) and transient (decays over minutes). The split is operational: permanent impact bounds the strategy size; transient impact bounds the execution speed.
- square-root-lawshared measurementEmpirically, impact scales as √(executed volume / daily volume) across markets, asset classes, and decades. The square-root law is one of the most robust regularities in finance — and it falsifies any linear-impact model that does not collapse to it.
This concept is a node in the curriculum DAG. The full lab — page blocks, done state, references — has not been authored yet. The relations above describe where it sits in the graph.
Author at: content/concepts/market-impact/card.ts