Direct Answer
The S&P 500 is a rule-based measurement of large-cap u.s. equities, maintained by S&P Dow Jones Indices. Like every index it owns nothing: it is a number produced by applying a published weighting formula to a selected list of companies, revised on a schedule the provider sets.
What this index covers
The S&P 500 covers large-cap u.s. equities, within the United States market. S&P Dow Jones Indices defines which securities are eligible, how they are selected from that pool, and how much each one contributes to the published number.
The name states a target of 500 companies. A target is not a guarantee of the exact count on any given day: corporate actions, dual share classes and pending additions all move the real number around it.
How constituents are weighted
Swoopr has not verified the weighting method for this index against S&P Dow Jones Indices's current methodology document, so none is stated here rather than guessed. The provider link below is authoritative.
Current S&P 500 constituents
S&P Dow Jones Indices publishes and licenses the S&P 500 constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights.
Related reading
- All stock market indexes: how indexes are built, weighted and revised.
- United States indexes: others covering the same region.
- Index concentration: measuring how much of an index sits in its largest holdings.
- Index rebalancing and inclusion effects: what happens to a stock when index membership changes.
Frequently Asked Questions
Who maintains the S&P 500?
S&P Dow Jones Indices maintains the S&P 500 and publishes the methodology document that defines its eligibility and weighting rules.
What does the S&P 500 measure?
It measures large-cap u.s. equities. The index is a calculated number applying a weighting formula to a selected list of companies, and it holds nothing itself.
Where can I see the current S&P 500 constituents?
S&P Dow Jones Indices publishes the current constituent list. Swoopr does not republish it, because index providers license constituent data and Swoopr holds no such licence.