Backtests assume fills at mid. Live trading pays spread, fees, and impact. The papers below are the core references for optimal execution, the square-root law, and modern microstructure views of metaorder impact.
Optimal execution
The framework behind TWAP/VWAP scheduling and implementation shortfall benchmarks. Start with Almgren-Chriss, then the empirical equity impact calibration.
Optimal Execution of Portfolio Transactions
Classic trade-off between market impact and timing risk. Defines the efficient frontier of execution strategies. Risk.net
Direct Estimation of Equity Market Impact
Empirical calibration of temporary and permanent impact on US equities. Practical coefficients for participation sizing. Risk.net
Optimal Execution of Portfolio Transactions: A Review
Accessible survey of the optimal execution literature through the early 2000s. Good bridge from theory to desk practice.
Square-root law and no-arbitrage impact
Temporary impact often scales with the square root of participation rate. Gatheral's work connects impact models to absence of dynamic arbitrage.
No-Dynamic-Arbitrage and Market Impact
Shows which impact functional forms are consistent with no-dynamic-arbitrage. Explains why linear impact is fragile.
How Markets Slowly Digest Changes in Supply and Demand
Metaorder impact, propagator models, and long memory in order flow. Foundational microstructure perspective.
Practical checklist
- Estimate impact per name using your own fill data when possible
- Stress test at 2x and 5x intended participation rate
- Separate temporary and permanent impact in post-trade analysis
- Re-run backtests with a sqrt or linear impact penalty
For ongoing microstructure preprints see arXiv q-fin.TR.