What the screen is — and what it isn't
The candidate screen is a transparent, rule-based filter. It takes every U.S. equity that is not currently in the S&P 500, checks it against the index's published eligibility criteria, ranks the survivors by market cap, and sorts them into tiers. It measures how closely a company resembles the pool the index committee draws from — nothing more.
It is not a probability, a forecast, or a guarantee. Additions to the S&P 500 are decided by the S&P Index Committee at its sole discretion. Meeting every published rule is necessary but never sufficient: the committee can add a company that screens poorly or pass over one that screens perfectly. Treat a high tier as a description of the setup, not a prediction.
The eligibility gates
A company must clear every one of these hard gates to be counted as eligible. Failing any single gate makes it ineligible (and excluded from the screen):
- Domicile. The company must be U.S.-domiciled. A foreign country of incorporation does not disqualify a company that S&P still treats as U.S.-domiciled — chiefly one that files a domestic annual report (10-K) rather than a foreign one (20-F / 40-F), the same test the SEC uses for a domestic registrant. Flex Ltd — incorporated in Singapore but a 10-K filer — is a recent example.
- Security type. Common stock, equity REITs, and business development companies (BDCs) qualify. ETFs, ADRs, MLPs, closed-end funds, and SPACs do not.
- Market cap. At or above the published threshold — $22.7B as of 2025-07-01. The float-adjusted figure must be at least half that ($11.35B).
- Public float. More than 50% of shares must be publicly floated.
- Liquidity. A float-adjusted liquidity ratio of at least 0.75, with at least 250k shares traded in each of the prior 6 months.
- Profitability. Positive as-reported (GAAP) earnings in the most recent quarter and over the trailing four quarters combined.
- Seasoning (screen heuristic). Our screen also requires at least 12 months since the company's IPO. S&P publishes no explicit IPO seasoning rule; this gate is our own filter to exclude recently listed companies that lack a track record.
Ranking and tiers
Eligible companies are ranked by market cap among all non-members. A 0–100 readiness score blends how far each clears the gates, weighting market-cap headroom 40%, liquidity 25%, public float 20%, and profitability 15%. Any factor whose data is missing is dropped and the remaining weights renormalize.
The market-cap rank drives the tier — the largest eligible non-members are the pool the committee realistically draws from:
- Strong candidate. Passes every published eligibility rule and is among the largest companies not yet in the index — the kind of profile the committee draws from. Not a prediction.
- On the bubble. Passes the published rules and is large enough to be in the conversation, but sits behind bigger eligible names.
- Eligible (crowded). Meets the published rules, but many larger eligible companies rank ahead of it.
Concretely: eligible names ranked in the top 10 by market cap are tiered Strong candidate; through rank 40, On the bubble; everything eligible below that is Eligible (crowded).
When additions happen
Constituent additions and removals happen continuously throughout the year, driven by corporate events — mergers, acquisitions, spin-offs, bankruptcies, and delistings. There is no fixed additions schedule.
The quarterly rebalance (third Friday of March, June, September, and December) updates float-adjusted constituent weights only. It is a float-and-weight checkpoint, not an additions window. S&P occasionally times a new addition to coincide with a rebalance, but that is coincidental — the committee can and does add companies at any time a corporate event creates an opening.
The sector-balance overlay
On top of the additive factors, a single overlay nudges the score by sector. The committee tends to keep the index roughly representative, so a candidate in a sector that is currently under-weight versus the equal-sector baseline gets a small boost, and one in an over-weight sector a small discount. The overlay is capped to a narrow band (roughly ±8%) so it can nudge, never dominate. Current sector weights are derived from the index's own constituents.
Data sources and known limits
The screen is re-materialized nightly. A few honest caveats:
- Float and liquidity ratio. The exact public-float and float-adjusted-liquidity figures the committee uses are not in our data set. Where they are unavailable, those checks are flagged rather than enforced — so a listed candidate could still fail them.
- Security-type classification. We distinguish common stock, REITs, and funds with a best-effort heuristic from the company profile. Mortgage REITs and MLPs that are mislabeled upstream may slip through.
- Domicile signal. For a foreign-incorporated company we read U.S. domicile primarily from its latest annual-report form type (10-K vs 20-F / 40-F), backed by a short manual list. Where filing data is missing, we fall back to the country of incorporation — so a U.S.-managed foreign filer could be held out until its filing data is available.
- Discretion is the ceiling. Even a perfect data set could not predict a committee decision. See the disclaimer below.
Disclaimer
This is a transparent, rules-based screen — not a prediction or a probability. Additions to the S&P 500 are decided by the S&P Index Committee at its sole discretion; meeting every published criterion is necessary but never sufficient, and the committee can add a company that screens poorly or pass over one that screens well.
Related
See the live screen on the S&P 500 likely next additions page, or the historical record on the additions & removals page.