Index Weight (constituent weight): Definition and Formula

Definitions

A 5% weight means that constituent represents 5% of the declared index weighting basis at that point.

Weight is the constituent's eligible weighted value divided by the aggregate eligible value, after currency, float, capping, and timing rules.

Current weight, target weight, opening weight, and return contribution are different quantities.

w_i = X_i / sum(X_j)

LaTeX: w_i=X_i/\sum_j X_j

Symbol	Meaning	Unit
`X_i`	eligible weighted value for constituent i	value unit
`X_j`	eligible weighted values for all constituents	value unit

Output unit: decimal weight

A governed index record identifies index weight with its applicable methodology version, effective time, source, and units.

Index Weight does not have one universal implementation without the named index methodology, data cutoff, and governance context.

S&P Dow Jones Indices Index Mathematics Methodology S&P Dow Jones Indices · first party methodology
Supports: preferred label, short definition, technical definition, formula
Limits: Authoritative for the provider's indices; conventions are not universal defaults for every index or security-level return series.
Fintech Builder Glossary Definition Contract The Fintech Builder · internal governed contract
Supports: variant distinction
Limits: Defines governed platform behavior rather than claiming these policies are universally prescribed by external McClellan methodology.