Public float is the portion of a company's shares that is available for trading by the public, excluding shares held by insiders, controlling shareholders, and other closely held blocks.
A company's total shares outstanding are not all freely traded. Some are held by founders, executives, directors, and large strategic or controlling shareholders who do not routinely buy and sell. The public float is what remains: the shares actually available to the broad market. Float is usually expressed as a number of shares or as a percentage of shares outstanding.
Float matters because it shapes how a stock trades. A small float means fewer shares change hands, which tends to produce lower liquidity and higher volatility, since even modest orders can move the price. A larger, well-distributed float generally supports smoother trading and tighter spreads. For small and micro-cap companies, a thin float is a common reason a stock is difficult to trade and difficult for larger investors to enter or exit.
Float also affects institutional interest directly. Many funds have internal limits on how much of a company's float they are willing to own, and they need enough available shares to build a meaningful position without dominating the stock. A company with a very small float can therefore be effectively off-limits to certain investors regardless of how attractive the business is.
Understanding float is part of understanding a company's investability. A strong business with a tiny float faces a different set of investor relations challenges than one with ample tradable shares. Broadening the shareholder base and, over time, supporting healthy liquidity are ways a company can make its float work in its favor.