Iterative Cap Redistribution
Install and import
npm install fintech-algorithmsimport { calculate } from "fintech-algorithms/index-and-benchmark-engineering/weighting-and-capping/iterative-cap-redistribution";Signature
calculate(data)Worked example
verified This is the worked example published in the article, replayed by the test suite on every run. The output cannot drift.
Input
{
"ids": ["A", "B", "C", "D", "E", "F"],
"rawWeights": [0.42, 0.22, 0.14, 0.1, 0.07, 0.05],
"cap": 0.25,
"tolerance": 1e-10,
"maxIterations": 100
}Call
calculate(data)Returns
object with 6 fields: ids, weights, cap, iterations, maxWeight, weightSum
{
"ids": ["A", "B", "C", "D", "E", "F"],
"weights": [0.25, 0.25, 0.194444, 0.138889, 0.097222, 0.069444],
"cap": 0.25,
"iterations": 3,
"maxWeight": 0.25,
"weightSum": 1
}Diagrams
Calculation flow
Iterative Cap Redistribution calculation flow
flowchart LR
A["Point-in-time inputs"] --> B["Validate units and timing"]
B --> C{"Contract feasible?"}
C -->|No| D["Reject with reason"]
C -->|Yes| E["Calculate Iterative Cap Redistribution"]
E --> F["Recompute invariants"]
F --> G{"Checks pass?"}
G -->|No| D
G -->|Yes| H["Publish audited output"]
Iterative Cap Redistribution methodology state
stateDiagram-v2
[*] --> FrozenInputs
FrozenInputs --> Validated: contract passes
FrozenInputs --> Rejected: missing or infeasible
Validated --> Calculated: apply named rule
Calculated --> Audited: invariants pass
Calculated --> Rejected: invariant fails
Audited --> Published: version and timestamp recorded
Published --> Revised: approved correction
Revised --> FrozenInputs: rebuild from retained source state
How it works
This page states the contract — how to call it correctly. The article explains the concept: why it works, and where it breaks.
References
- S&P Dow Jones Indices Index Mathematics Methodology — S&P Dow Jones Indices
- S&P DJI Equity Indices Policies & Practices — S&P Dow Jones Indices
- FTSE Russell Capping Methodology — FTSE Russell, LSEG
- FTSE Russell Index Policy and Methodology Library — FTSE Russell, LSEG
- MSCI Global Investable Market Indexes Methodology Library — MSCI
- MSCI Minimum Volatility Indexes Methodology — MSCI
- S&P Risk Control 2.0 Indices Methodology — S&P Dow Jones Indices
- Principles for Financial Benchmarks — International Organization of Securities Commissions
- Regulation (EU) 2016/1011 — European Union
- Portfolio Selection — Harry Markowitz
- On the Properties of Equally-Weighted Risk Contributions Portfolios — Sébastien Maillard, Thierry Roncalli, and Jérôme Teïletche
- Fundamental Indexation — Robert Arnott, Jason Hsu, and Philip Moore
- FTSE Currency Hedging Methodology Overview — FTSE Russell, LSEG