Definition
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.
Indian indices apply capping to comply with diversification norms and regulatory limits, for example single-stock caps in sectoral or thematic indices and the 25%/35% diversification rules that mutual-fund-linked indices must respect. When a stock's weight breaches the cap at a review, the excess is redistributed to others.
Capping is re-applied at each rebalancing, so a fast-rising constituent is periodically trimmed in the index, forcing tracking funds to sell it and buy laggards. This introduces a small contrarian, mean-reverting tilt and is an important determinant of an index's turnover and concentration risk.
Related terms
- Free-float Market CapitalisationFree-float market capitalisation values a company using only the shares available for public trading, excluding locked-in holdings of promoters, governments and strategic investors.
- 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 MethodologyIndex 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.
- 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.
Plain-English explainer from The Dispatch Investors Encyclopedia. General information, not financial advice.