How this instrument works
Free float is the slice of a company's stock that can actually change hands on the open market — total shares outstanding minus the portion locked up with insiders, founders, governments, or other strategic holders who are not selling. A company can report 50 million shares outstanding on its balance sheet while only 30 million of that count ever trades, because the remaining 20 million sit in restricted or closely-held accounts subject to a lock-up, a control agreement, or plain founder inertia.
Index providers such as the S&P and MSCI do not weight constituents by total shares outstanding; they weight by float, because a holding nobody can buy should not move a benchmark the way a fully liquid one does. A committee tracking a newly public company revisits that figure every time a lock-up expires, an insider files to sell, or a strategic stake changes hands, since each event changes how much stock is actually available to absorb buy and sell orders.
The subtraction only reflects what a filing discloses as restricted or closely held; it says nothing about how thinly a stock actually trades day to day, since even freely tradable stock can sit unmoved in index funds and pension accounts for years. A shrinking float against a fixed outstanding count also proves nothing about value on its own — it can come from a company retiring public shares through buybacks just as easily as from insiders quietly accumulating more.
- Enter Total shares outstanding, taken from the company's latest 10-K or 10-Q cover page.
- Enter Restricted / closely-held shares — stock held by insiders, founders, or other parties under a lock-up or control agreement.
- Read Free float in the result: the portion of the company available for public trading.
- Recalculate after an insider sale filing or a lock-up expiry — the figure shifts with each such event, even when the outstanding count does not.
Worked example — a 50 million-share company
Take a company with 50,000,000 total shares outstanding, of which 20,000,000 are held by its founders and other insiders under a lock-up. Free float = 50,000,000 − 20,000,000 = 30,000,000 — the portion of the company actually available for public trading rather than sitting with a restricted holder.
That 30,000,000-share float, not the full 50,000,000 outstanding, is the figure an index committee would use to weight the stock in a benchmark such as the S&P 500, and it is the number traders watch when judging how easily a large order can move the price without the other 20,000,000 shares ever reaching the market.
Questions
What counts as a restricted or closely-held share?
Restricted stock cannot yet be sold freely by the insiders who hold it — it sits under an IPO lock-up, an employee vesting schedule, or an SEC Rule 144 holding period. Closely-held stock is simply stock a founder, executive, government, or strategic partner has chosen to keep; nothing legally stops a sale, but it is not part of the tradable supply either. Companies disclose both figures in the shares-outstanding note of their 10-K filing.
Why isn't free float the same as market capitalization?
Market capitalization multiplies total shares outstanding by price, valuing every share the company has issued, restricted or not. Free float only measures how much of that count can actually trade; multiplying it by price gives the smaller, float-adjusted figure index providers use for weighting instead of full market cap.
Does free float change over time?
Yes. It rises whenever a lock-up expires, an insider files to sell, or the company issues new unrestricted stock, and it falls when insiders buy more shares or the company retires public stock through a buyback. Index committees reassess the figure on a fixed review schedule and after major events like secondary offerings, precisely because it moves.
Why do index funds weight by float instead of total shares?
An index weighted this way counts only the stock that could realistically be bought, so its weights reflect what is tradable rather than what merely exists on paper. Weighting by total shares outstanding would overstate a company's pull on the index if a large block of its stock is locked away with insiders and never trades.
Is a low float automatically a red flag?
No — a small float can simply mean the founders retained a large stake, common right after an IPO. It does mean the stock can swing harder on comparatively small buy or sell orders, since fewer shares are absorbing that volume, so thinly floated names often move more than their market cap alone would suggest.
Where do I find a company's restricted share count?
Public companies disclose insider and restricted holdings in the share-count line of a 10-K or 10-Q cover page, in proxy statements, and in Schedule 13D or 13G filings with the SEC. Market-data providers also publish a float figure directly, though what each one classifies as restricted varies slightly.
References
Read this first: This instrument shows arithmetic, not advice. Real offers add fees, taxes and terms that vary by lender and place — verify the figures against your actual paperwork before deciding anything.