Definition
Index Methodology
Index methodology is the detailed, published rulebook governing how an index selects, weights, caps and reviews its constituents, ensuring the index is transparent, replicable and consistent over time.
Indian index providers such as NSE Indices and BSE publish methodology documents covering eligibility, weighting (free-float, equal-weight or factor-based), capping limits, review schedule and treatment of corporate actions. Investors and fund managers rely on this rulebook to understand what they are tracking.
Methodology determines an index's behaviour: sector and stock concentration, turnover at rebalancing, and exposure to factors. A change in methodology, such as adding a cap or shifting the review frequency, can meaningfully alter the index and the funds that track it, so providers consult and announce changes in advance.
Related terms
- Index ConstructionIndex construction is the set of rules defining how an index is built, including eligibility criteria, weighting scheme, number of constituents and selection thresholds for liquidity and size.
- Index RebalancingIndex rebalancing is the periodic adjustment of constituent weights back to their methodology-defined levels, accounting for price moves, capping limits and corporate actions, without necessarily changing the membership.
- ReconstitutionReconstitution is the periodic review in which an index changes its actual constituents, adding stocks that now meet the criteria and removing those that no longer qualify.
- Capping (Index)Capping is an index rule that limits the maximum weight any single constituent, or group such as a sector, can have, preventing excessive concentration and ensuring diversification.
Plain-English explainer from The Dispatch Investors Encyclopedia. General information, not financial advice.