What it means
When a private company decides to sell shares to the public through an initial public offering, it rarely lists all of its existing shares on the stock exchange. Company founders, early venture capital backers, and senior executives usually retain a large chunk of the ownership.
These insider shares are locked away, meaning they do not circulate freely. The remaining portion forms the public float.
Why does this matter for non-finance managers? The size of the public float directly influences how easily a stock trades and how volatile its price might become.
If a company has a very small public float, meaning most shares are controlled by just a few people, even a small trade can cause wild swings in the share price. Conversely, a large float usually means a more stable and liquid market for the company stock.
Stock exchanges and major market indexes often look closely at the public float before letting a company join their lists, because they want enough trading activity to support normal market operations. In daily practice, financial analysts use the public float to calculate market capitalisation more accurately, focusing on the shares that actually matter for public trading.
For business leaders, keeping an eye on the float helps in understanding market sentiment, planning future share issuances, and managing shareholder relations effectively. It acts as a vital gauge of market depth, helping investors judge whether they can easily buy or sell their holdings without drastically moving the share price.
Imagine a housing estate with 100 homes where the builder keeps 70 to rent out and refuses to sell them. Only 30 houses are listed on the open market for buyers, and those 30 houses represent your public float.
In practice
Real-world examples
Example 1
TechStart Inc. issues 10 million total shares. Founders and executives hold 7 million. The public float is 3 million shares, which are traded freely by everyday retail investors on the stock market. A single large order for 300,000 shares would be 10% of the float, so it could move the price noticeably.
Example 2
LocalBrew Pubs lists on a regional exchange with 1 million shares. The founding family keeps 600,000 to maintain control. The public float of 400,000 shares is bought by local fans and small investment funds, and the thin trading means buyers sometimes wait days to fill an order.
Example 3
MegaRetail PLC has 100 million shares total. Executives own 10 million, and a strategic partner holds 40 million that it has agreed not to sell. The remaining 50 million shares form the public float available to the general investing public, which is why its shares trade easily every day.
Think of it
Imagine a housing estate with 100 homes. The builder keeps 70 houses to rent out and refuses to sell them. Only 30 houses are listed on the open market for buyers. Those 30 houses represent your public float.
Formula
Calculation
Public Float = Total Shares Outstanding - Restricted Shares (Insider Holdings + Locked-up Shares)
Worked example: a company has 10,000,000 total shares issued, and insiders and founders own 6,000,000 restricted shares. Public Float = 10,000,000 - 6,000,000 = 4,000,000 shares.
The float percentage is 4,000,000 / 10,000,000 = 40%. If the shares trade at $12, the full market capitalisation is 10,000,000 x $12 = $120,000,000, but the float-adjusted market capitalisation, which counts only freely traded shares, is 4,000,000 x $12 = $48,000,000.Case study
Seen in the real world
This is a fictional, illustrative scenario. BrightRetail, a growing fashion chain, prepared to float on the London Stock Exchange. The founding family owned 8,000,000 shares, and early angel investors held 2,000,000 shares subject to a lock-up agreement for the first year. BrightRetail issued 5,000,000 new shares to the public during its listing, bringing the total shares outstanding to 15,000,000.
When calculating the initial public float, the finance team excluded the 8,000,000 family shares and the 2,000,000 locked-up angel shares. This meant the public float was exactly 5,000,000 shares, representing one-third of the total company. During the first week of trading, high demand met this relatively small supply of 5,000,000 shares. Because the public float was constrained, the share price jumped significantly as eager buyers competed for a limited pool of stock.
At an assumed price of $4, the full market capitalisation was 15,000,000 x $4 = $60,000,000, while the float-adjusted figure was 5,000,000 x $4 = $20,000,000. The Chief Financial Officer monitored the float closely, knowing that once the one-year lock-up expired the float would rise to 7,000,000 shares, or about 47% of the total. The larger float might calm the price volatility.
Watch out
Common mistakes
- Assuming total shares issued and public float are always the same number.
- Forgetting that shares held by company directors count as restricted and are excluded from the float.
- Believing that a small public float automatically means a company is performing well financially.
Questions
People also ask
Why do companies keep some shares out of the public float?
Founders and executives retain large blocks of shares to maintain voting control over the business and align their financial interests with long-term company growth.
Can the public float change over time?
Yes. The float increases if the company issues new shares or if insiders sell their locked shares. It decreases if the company buys back its own shares from the open market.
Is a larger public float always better?
Not necessarily. A larger float provides better trading liquidity and stability, but a smaller float can sometimes lead to sharper price gains if demand suddenly spikes.