GUIDE

How the league is calculated

The one-line version

Every company in the league table has a derived market capitalization: the daily closing price from the IEX exchange, multiplied by the number of shares outstanding that the company itself reported to the US Securities and Exchange Commission. Companies are sorted by that number, largest first, and the first hundred make the table. Everything else on this page explains the details behind that sentence, including the cases where it is not quite so simple.

Who can enter

The starting list is the SEC's own directory of listed tickers. We keep securities shown on Nasdaq, NYSE, NYSE American, NYSE Arca and Cboe, and we group them by the company's SEC identifier (its CIK) rather than by ticker. That way a ticker change does not create a brand-new company, and a company with several listed securities is treated as one issuer.

Some listings are removed before any valuation happens. Preferred-series tickers and a short, sourced list of other non-common instruments, such as notes and depositary symbols, are dropped because they are not the common equity we are measuring. A separate, sourced list excludes commodity and exchange-traded trusts that are not operating companies. The category code alone is never used to exclude a company, because the same code also covers genuine operating businesses.

Where the share count comes from

Public companies file reports with the SEC, and the cover page of each report is tagged in a machine-readable format. One of those tags, part of the Document and Entity Information (DEI) set, is the number of shares outstanding. We take the most recent value whose reporting period ended within the previous 400 days and which had already been filed by the snapshot date. If several filings describe the same period, the newest filing wins. If the newest filing contains conflicting values that cannot be explained, the company is left out rather than guessed at. Repeated copies of the same number are never added together.

Several share classes

Some companies have more than one class of listed common stock. The cover-page figure alone cannot tell us how many shares belong to each class, so a company with several tickers only qualifies when a hand-maintained mapping lists every class, its share count and the SEC filing that supports it. Each class is multiplied by the close of its own ticker and the results are added up. A class without its own listing can be valued through another listed class using a documented conversion ratio. If the mapping is missing, incomplete or out of date, the company is excluded and the reason is recorded in the snapshot.

ADRs and foreign issuers

A US-listed American depositary receipt usually represents a fixed number of the underlying ordinary shares, but the SEC share count describes the ordinary shares. Multiplying one by the other directly would give a wildly wrong answer. For these issuers we require a documented ratio of underlying shares per receipt before a value is published. Foreign-form filers, and issuers with extremely large share counts that are incorporated outside the United States, are treated as needing that ratio. Without it they are excluded. The large-count rule is a safety heuristic, not proof that a company has depositary receipts.

Sanity checks and exclusions

A company is also left out if it has no IEX bar for the completed session, no usable SEC share count, or a share count too old to trust. As a guard against data errors, any market cap that differs from the previous retained snapshot by more than a factor of three in either direction is excluded before ranking. The homepage coverage panel shows how many issuers were eligible and how many were excluded in the latest capture (3155 eligible from 6036 in the listing universe, 3265 excluded in the snapshot dated 2026-10-30).

Ranking and ties

Market caps are rounded to whole US dollars and sorted from largest to smallest. If two companies end up with exactly the same value, the one with the lower stable company identifier comes first, so the order never depends on the order of a file. The top hundred are published with rank 1 to 100.

Rank change and change percentage

Rank change is the company's rank in the earlier snapshot minus its rank in the current one, so a positive number means it moved up. A company that was not in the earlier top hundred has no earlier rank and is labelled New; that word does not mean newly listed. We never assume the missing rank was 101. Change percentage is the current derived market cap divided by the previous retained one, minus one. It compares with the most recent earlier snapshot, which may be several sessions back after a weekend, a holiday or a gap. Because market cap is price times shares, the figure can move when a company reports a new share count as well as when its price moves.

Known limitations

• Stale share counts. A cover-page count is as of its own date, often weeks before the snapshot. Buybacks, issuance or splits since then are not reflected unless a split has been manually sourced and recorded.
• IEX is not the whole market. The close comes from a single exchange, not the consolidated official close. For heavily traded names the two usually sit close together, but they can differ, especially for thinly traded securities. The feed used is recorded in each snapshot.
• Broad labels. Country is the SEC incorporation jurisdiction, not where a company operates, and sector is a broad SEC industry group.
• Derived, not official. These are our own calculations from public inputs. They are not an official index and may differ from figures published elsewhere.

For primary sources, see SEC EDGAR, the SEC's EDGAR APIs and the Alpaca documentation for market data.

Informational only, not investment advice.