What Are the S&P 500 Inclusion Criteria? Market Cap, Float, and Earnings

To join the S&P 500, a company must clear a stack of quantitative tests and then be selected by the index committee. The S&P 500 inclusion criteria set a $22.7 billion minimum market capitalization, a float and liquidity floor, U.S. domicile, a listing on an eligible U.S. exchange with at least 12 months of trading, and positive GAAP earnings in the most recent quarter and across the last four combined. Meeting every rule earns eligibility, not a seat. A committee picks who actually goes in.

Market Capitalization Threshold

The minimum total company-level market cap is $22.7 billion, a figure S&P Dow Jones Indices updated in July 2025. The prior threshold was $20.5 billion, and $18 billion before that. S&P revisits the number periodically so the index keeps tracking the large-cap segment as overall valuations move.¹

Clearing that headline number is not enough on its own. The float-adjusted market cap at the individual security level must also reach at least 50% of the total company-level minimum. In practice, that means the publicly tradable shares need a market value of roughly $11.35 billion or more.¹

Public Float and Liquidity

The S&P 500 uses a float-weighted methodology, so thinly traded stocks with concentrated ownership do not qualify even if their headline market cap is huge. A company must have an Investable Weight Factor of at least 0.1, meaning at least 10% of its shares must be available to the general public. Shares locked up by insiders, controlling shareholders, or other strategic holders do not count.²

The stock also has to trade actively. Two liquidity tests apply:

The ratio of annual dollar value traded to float-adjusted market cap must be at least 0.75. A stock with a $15 billion float that traded only $5 billion in shares over a year would fail (ratio of 0.33).
The stock must trade a minimum of 250,000 shares in each of the six months before the evaluation date.²

The reason is practical. When trillions of dollars in passive funds rebalance, the stock has to absorb that flow without wild price distortions.

U.S. Domicile

The S&P 500 is meant to reflect the U.S. economy, so only U.S.-domiciled companies qualify. S&P Dow Jones determines domicile through a multi-factor test rather than by looking only at the state of incorporation. The U.S. share of fixed assets and revenues must represent a plurality of the company’s total, though it does not need to exceed 50%. If fixed assets and revenues point to different countries, fixed assets take priority.³

If that test is inconclusive, S&P may still treat a company as U.S.-domiciled when its primary listing, headquarters, and place of incorporation are all in the United States. The geographic breakdown comes from whatever the company reports in its own annual filings.³

Eligible U.S. Exchange Listing

The stock has to trade on an eligible U.S. exchange. The list is broader than many people assume: the New York Stock Exchange, Nasdaq, NYSE Arca, NYSE American, Cboe BZX, Cboe BYX, Cboe EDGA, Cboe EDGX, the Nasdaq Global Select Market, and the Nasdaq Global Market.²

One timing rule catches newly public companies off guard. The stock must have been trading on an eligible exchange for at least 12 months before the committee will consider it. For companies that went public through a SPAC merger, S&P treats the de-SPAC transaction as the equivalent of an IPO, so the 12-month clock starts from the date the SPAC deal closed rather than from when the blank-check company first listed.²

The Earnings Test

This is where the S&P 500 filters out high-flying companies that generate attention but not profit. The rule has two parts, and a company must pass both:

GAAP net income from continuing operations must be positive in the most recent fiscal quarter.
The sum of GAAP net income from continuing operations over the four most recent consecutive quarters must also be positive.²

The “continuing operations” language matters. One-time gains from selling a division, or unusual write-downs from discontinued segments, are stripped out. The committee wants to see that the ongoing business makes money under standard accounting, not that a profitable quarter got engineered through asset sales.

This is one of the biggest practical barriers to inclusion. A company can easily clear the market-cap and liquidity thresholds while remaining unprofitable, and many large tech and biotech firms have waited years for the S&P 500 specifically because they could not string together the necessary quarters of positive GAAP earnings.

Eligible Security Types

Only certain kinds of securities qualify. Common stock is the default. Real estate investment trusts are eligible, with the notable exception of mortgage REITs, and business development companies are also allowed.

The list of what cannot get in is longer: closed-end funds, exchange-traded funds, American depositary receipts, limited partnerships, and SPACs. A SPAC itself can never join the index, though the operating company that emerges after a de-SPAC merger can be considered once it has 12 months of post-merger trading history.²

Multi-Class Share Structures

From July 2017 through early 2023, S&P Dow Jones Indices barred companies with multiple share classes from being added to the S&P 500, regardless of size or profitability. Firms already in the index at the time were grandfathered in, which is how Alphabet and Meta stayed as constituents. In April 2023, following a public consultation, S&P reversed the policy. Companies with dual-class or multi-class voting structures are now eligible, provided every other criterion is met.

The Index Committee’s Role

Passing every quantitative test puts a company on the eligibility list. It does not put the company in the index. The final call belongs to the S&P Dow Jones Indices Index Committee, a small group of analysts and economists who exercise real discretion. That is why the S&P 500 is often described as a semi-rules-based index rather than a purely mechanical one.²

The committee’s most visible concern is sector balance. It compares each sector’s weight in the S&P 500 against that sector’s weight in the broader S&P Total Market Index. If technology is overrepresented relative to the full market, the committee may pass over an otherwise-qualified tech candidate in favor of one from an underweight sector such as energy or materials.

The committee also considers whether a company looks like a stable, long-term constituent. A stock that rocketed past the market-cap minimum on a speculative spike may get a longer look before being added. There is no queue, and meeting the criteria does not entitle any company to the next open slot.

How Additions Actually Happen

The index is fixed at exactly 500 constituent companies, so every addition requires either a removal or an existing vacancy. Vacancies most commonly arise from mergers, acquisitions, or spin-offs that cause a current member to be delisted. Changes also happen during quarterly rebalancing, which takes effect on the third Friday of March, June, September, and December.²

Changes are typically announced about five business days before they take effect, giving index funds time to adjust. The committee meets monthly but can announce changes outside that schedule when a corporate event forces faster action, such as a merger closing suddenly.

Staying In Is Easier Than Getting In

The bar for continued membership is deliberately lower than the bar for entry. S&P’s own guidelines state that the market-cap criteria are for additions, not for ongoing membership. A current constituent whose market cap drifts below $22.7 billion is not automatically removed and stays unless “ongoing conditions warrant an index change.”¹

The buffer exists for a reason. Without it, a stock hovering near the threshold would bounce in and out of the index, forcing index funds into pointless and expensive round-trips. Removals more often come from corporate events, acquisitions, bankruptcies, or a shift of domicile outside the United States, than from a slow drift in valuation.²

1
S&P Dow Jones Indices. S&P Dow Jones Indices Announces Update to S&P Composite 1500 Market Cap Guidelines
2
S&P Global. S&P U.S. Indices Methodology
3
S&P Global. S&P Dow Jones Indices Clarifies Domicile Language for U.S. Indices