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Key Takeaways
- Free float starts with shares outstanding and removes excluded strategic holdings.
- Float percentage divides free-float shares by shares outstanding.
- Float-adjusted market cap multiplies free-float shares by the stock price.
- Public float includes eligible institutional holdings as well as retail holdings.
- A small float concentrates the tradable supply; compare it with volume, spread and depth to see whether the stock actually trades thin.
What is free float?
Free float is the portion of a share class available for public trading after strategic holdings are removed. It equals shares outstanding minus the strategic block, and it is the supply that index weights, short-interest ratios and low-float screens run on.
Public float includes institutional holdings such as funds and pensions alongside retail holdings; only strategic blocks come out.
Formula
Free-float shares = shares outstanding × investable weight; free-float market cap = share price × free-float shares- Free-float shares are the shares the public can trade, after strategic holdings such as insider, parent-company and government stakes come out.
- Investable weight equals free-float shares divided by shares outstanding.
How to calculate free float and float-adjusted market cap
A company has 120 million shares outstanding at $25 per share, including 30 million shares in excluded strategic holdings.
- 120 million − 30 million = 90 million free-float shares
- 90 million / 120 million = 75% investable weight
- 120 million × $25 = $3.0 billion total market capitalization
- 90 million × $25 = $2.25 billion free-float market capitalization
The company has 90 million free-float shares, equal to 75% of shares outstanding. At $25, float-adjusted market cap is $2.25 billion and total market cap is $3 billion.
Float-adjusted indexes weight each stock by its float market value, $2.25 billion here against $3 billion total. A float change at the next index review moves the stock’s weight, and index funds trade to match.
How traders read float alongside trading activity
A small float concentrates the tradable supply, which is why traders screen for it before catalysts and squeezes: the same buying meets fewer available shares. Compare trading volume with that supply, then examine the bid-ask spread and market depth for the execution picture.
Short interest divided by float shows how much of the public supply is sold short. Days to cover divides short interest by average daily volume to show how many sessions of normal trading a buyback would take. A large share of the float sold short with many days to cover is the classic squeeze setup.
Issuance, buybacks, strategic stake sales and lockup releases change the share count or the strategic block. A lockup release adds sellable supply on a known date, so mark it on the calendar and watch volume into it. Into that date, options flow shows which strikes and expirations around the release draw the largest premium, and the options profit calculator prices your position through the lockup date.
Limitations of free float
- Check the provider. Each one decides which holdings count as strategic, so two data sources can publish different floats for the same stock.
- Update the float after every share event. Issuance, buybacks, stake sales and lockup releases change it between a provider’s updates.
- Confirm a low float with the tape. Volume, spread and depth show whether the small supply actually trades thin and swings wide.
- Check who holds the float. When funds and pensions hold much of it, fewer shares change hands than the float suggests.
- Quote each short ratio with its denominator: float for the short-interest percentage, average daily volume for days to cover.
Bottom line
Free float measures the shares available to public investors, and float-adjusted indexes use it to weight their constituents. Use it to frame a stock’s supply, judge activity with volume, spread and depth, and keep float, shares outstanding and average volume distinct when you calculate short-interest ratios.
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Sources and Further Reading
How entries are sourced, calculated and updated: editorial methodology.