Shares outstanding counts every share a company has issued and not bought back; the float is the slice of those shares the public can actually trade. The gap between them is made up of insider, controlling-holder and locked-up shares. It decides how much stock is really available when a crowd shows up, which is why a quote screen can show SpaceX with a float worth about $54 billion against share classes that add up to nearly $2 trillion at the Class A price. Most traders grab both numbers from a quote screen. That is a mistake, because the screen is often wrong.

Below: the SEC definitions, four real tickers checked against their filings at the October 19, 2026 close, and a checklist for doing it yourself.

The definitions, straight from the SEC

Shares outstanding is the issued share count held by investors, insiders included. Every 10-K and 10-Q cover page must give it. The Form 10-K instructions ask the registrant to "indicate the number of shares outstanding of each of the registrant's classes of common stock, as of the latest practicable date." Note the words each class. That detail matters below.

Float (public float) is the part held by non-affiliates. Under SEC Rule 12b-2, an affiliate is a person that "directly, or indirectly through one or more intermediaries, controls, or is controlled by, or is under common control with" the company. In practice that means officers, directors and controlling holders. The same rule computes public float by multiplying the non-affiliate share count by the last sale price. It then uses that dollar figure to sort filers:

• Accelerated filer: non-affiliate equity of $75 million or more, but less than $700 million.
• Large accelerated filer: $700 million or more.
• Smaller reporting company: public float under $250 million.

Each test is measured on the last business day of the second fiscal quarter.

Restricted and insider shares are the rest: affiliate holdings, plus pre-IPO stock that Rule 144 or a lock-up keeps off the market.

Where each number lives:

• 10-K / 10-Q cover: the share count by class, with an as-of date.
• 10-K cover: the aggregate market value held by non-affiliates. $AAPL's fiscal 2025 10-K put it at about $3,253,431,000,000 as of March 28, 2025. Apple excluded executive officers' and directors' shares for that figure.
• 424B4 prospectus: the "outstanding immediately after this offering" line, plus a "Shares Eligible for Future Sale" table showing when locked-up stock unlocks.

Four tickers, checked against the filings

The vendor columns come from Financial Modeling Prep (FMP) as pulled October 19–20, 2026. The filing column is what the company itself told the SEC. The float value is our arithmetic: vendor float shares × the October 19, 2026 close.

$SPCX: FMP's outstanding figure matches the 10-Q cover to the share, but it is the Class A count only. The 5.49 billion Class B shares are not in it. Per the 424B4, those shares carry 10 votes each and can convert into Class A. Count every class and the vendor's 4.75% float becomes 2.78%.

The vendor float has a second problem. It is below the 638.9 million Class A shares the 10-Q says SpaceX sold in its June IPO. The 424B4 calls those IPO shares freely tradable unless an affiliate holds them. FMP's dataset does not say how it gets to 365.9 million, so treat that number as one estimate, not a fact. Coverage of the IPO is in our piece on SpaceX's first earnings report.

$CBRS: FMP's outstanding count is 11,031,474 shares short of the three-class total on Cerebras' 10-Q cover. It is a small gap, but the float percentage moves with it.

$AAPL: this is the boring benchmark. Only about 25.1 million shares sit outside the vendor float, so the float and outstanding numbers are effectively the same.

$PUSA: this is the stale-data case. The S-3 count is 7.81 times FMP's count. At $1.94, the filing count gives a market value of about $327.5 million, against $41.9 million on the vendor count. The vendor float figure rests on the old base, so it tells you nothing until a post-merger filing gets processed. The merger math is in Powerus PUSA Stock After the Merger: The Numbers.

Why traders care about the gap

Low float, bigger moves. When only a few shares are available, a burst of orders has less stock to absorb it, so the price has to move further to find sellers. Historically, low-float names have shown outsized swings on news. In 2026 data, the largest overnight gap-up was $NXTC at +323.9%: it closed at $2.18 on July 13 and opened at $9.24 on July 14. FMP lists $NXTC at 2,934,133 float shares as of October 19, 2026. That float is measured months after the gap, so read it as an illustration, not proof.

Squeezes. Short interest is usually quoted as a percentage of float. Shrink the float and the same short position looks heavier, which leaves fewer shares to buy back if shorts rush for the exit. That is the mechanism. It does not predict anything.

Lock-ups refill the float. Unlocking restricted stock can multiply the tradable supply. The SpaceX 424B4 lays out more than a dozen staged releases, including:

• Up to 911.5 million shares after the first earnings release.
• Tranches of about 7% of the locked-up pool on set days from August 20 to October 24, 2026 (up to 328.4 million each on September 24, October 9 and October 24).
• Up to 1.3 billion after the September-quarter results.
• The rest of the 180-day pool on December 8, 2026, with Mr. Musk's shares locked until June 12, 2027.

Cerebras' lock-up ends at the earlier of the second trading day after its September 30, 2026 quarter's earnings or 180 days after the prospectus. Powerus lock-up shares release in thirds: at closing, at 90 days and at 180 days. How to read these schedules is covered in our IPO lock-up expiration guide.

Index weighting. The Russell US Equity Indexes methodology (v7.2, August 2026) has two rules that matter here:

• Members are weighted by "available (also called float-adjusted) market capitalization," which is the closing price times available shares.
• Companies with less than 5% of shares available are ineligible, with an exception for some fast-entry IPOs.

FTSE Russell computes float using its own definitions, so a vendor percentage cannot settle the question of eligibility.

Dilution. Outstanding shares can jump without a single trade. The Powerus S-3 registers a $250 million shelf plus a resale of 7,409,209 shares.

Checklist: verify float yourself

1. Open the latest 10-Q or 10-K cover on EDGAR. Write down the as-of date and add every share class.
2. Search for 8-Ks, S-1s, S-3s and 424B filings dated after that cover. Mergers, offerings and conversions all change the count.
3. For a recent IPO, read the 424B4 line "outstanding immediately after this offering" and its lock-up table.
4. Subtract affiliate holdings, using the beneficial-ownership table in the prospectus or proxy.
5. List what could still be added: warrants, options, RSUs and convertibles. These sit in the prospectus "excludes" list.
6. Compare your number with the vendor's. If they disagree, trust the filing and note the date.
7. Re-run the check after every corporate event.

Common mistakes

Using vendor counts after a merger or offering. $PUSA is the textbook case: 21.6 million shares on the vendor screen against 168.8 million in the October 19, 2026 S-3.

Confusing authorized shares with outstanding. Authorized shares are a ceiling written into the company's charter, not a count of what has been issued. SpaceX was authorized to issue 52,257 million common shares as of June 30, 2026, about four times what it actually had outstanding.

Ignoring warrants and options. The Cerebras 424B4 excluded two blocks from its share count:

• 33,445,026 Class N shares issuable under the OpenAI Warrant, at $0.00001 per share and subject to vesting.
• 28,361,707 option shares as of December 31, 2025.

The Powerus resale covers 5,049,542 pre-funded warrant shares. None of these show up in a cover-page count until they are exercised.

Counting one class. Dual-class stocks like $SPCX make a single-class percentage look precise when it is really partial.

FAQ

Is float the same as shares outstanding?

No. Outstanding covers every issued share, insiders included. Float excludes affiliate and restricted holdings. For $AAPL the two are nearly identical, at 99.83% per FMP. For a fresh IPO they can be far apart.

Where is a company's float in its SEC filings?

The 10-K cover reports the dollar value held by non-affiliates as of the last business day of the second fiscal quarter. The share count by class is on every 10-K and 10-Q cover. For a recent IPO, the 424B4 adds the lock-up schedule.

Does a low float mean a squeeze is coming?

No. A small float means fewer shares are available to trade. Historically that has gone along with bigger swings in both directions, but it says nothing about which way the next move goes.

Why does my broker show a different float?

Data vendors update on their own schedules and use their own methods. After a merger, offering or lock-up release, their numbers can lag the filings for weeks. More explainers are in our Analysis section and on the I'M A STOCK TRADER homepage.