Biggest Small-Cap Gaps September 24, 2026: Float and Volume

Direct answer: On September 24, 2026, the three largest measured small-cap gaps were APUS (+205%, float 1.51M), SRZN (+89%, float 11.75M) and PFSA (+71%, float 0.53M). These moves reflect extreme volume-to-float ratios—up to 35x for APUS—and illustrate how a tight float mechanically amplifies volatility. No specific catalyst is established here; only the measured numbers are reported.

The September 24, 2026 leaderboard: three measured gaps

The September 24, 2026 session saw three US small-caps post opening price gaps far above market averages. The numbers below come from the FloatVerify database, compiled from SEC filings and market feeds.

Ticker	Name	Gap	Intraday max	Float (M)	Price ($)	Volume (M)	Vol/float ratio
APUS	Apimeds Pharmaceuticals US, Inc.	+205%	+272%	1.51	5.04	53.4	~35x
SRZN	Surrozen, Inc. Common	+89%	+121%	11.75	33.69	7.7	~0.65x
PFSA	Profusa, Inc.	+71%	+116%	0.53	3.02	36.6	~69x

All three share a common trait: tight float (under 12 million shares), exceptionally heavy volume. The volume-to-float ratio exceeds 35x for APUS and 69x for PFSA. Every share available for public trading changed hands multiple dozens of times in a single session.

On a small-cap gapping like this, the concentrated turnover creates simple mechanics: when volume runs 30 or 40 times the float, you're no longer in a normal market. You're in a ping-pong where the same shares circulate repeatedly among active traders, and price climbs until a seller finally agrees to let go.

What float is and why it matters

Float represents the number of a company's shares actually available for public trading. You calculate it by subtracting from total outstanding shares those held by insiders, affiliates, and shareholders subject to sale restrictions (lock-up, contractual clauses).

Example calculation:

• Total outstanding shares: 15 million
• Shares held by insiders and affiliates: 13.5 million
• Public float: 1.5 million

This figure is never static. Every new share issuance—public offering (registered direct), private placement (PIPE), warrant conversion or option exercise—changes the outstanding share count and therefore the float. FloatVerify dates every data point because a float measured on September 15, 2026 can be obsolete by September 20 if dilution happened in between.

Float is read from SEC filings:

• Form 10-K (annual report): outstanding share count, insider holdings
• Form 10-Q (quarterly report): updated share count
• Form S-1 (offering registration): detail of upcoming dilution
• Form 424B5 (final prospectus): confirmation of shares issued and price

FloatVerify compiles these sources and surfaces divergences between them ("source split") rather than presenting a single figure that would mask contradictions. Because in reality, float data is never perfectly synchronized. Knowing where a number comes from—and when it was measured—is the difference between trading on fresh data or on a ghost.

Mechanism: volume, float and price pressure

When transaction volume for a stock exceeds its float multiple times in a single session, it creates concentrated price pressure. Every available share changes hands repeatedly. If buyer demand structurally exceeds seller supply, price rises mechanically until a new equilibrium forms.

Take APUS on September 24, 2026:

• Float: 1.51 million shares
• Volume: 53.4 million
• Ratio: ~35x

In theory, each share of the float traded 35 times. In practice, some shares never sold (long-term holders), while others circulated dozens of times among active traders. This concentrated turnover amplifies volatility: a sudden influx of buyers finds few sellers willing to part with shares at the current price. Price adjusts upward until a seller accepts.

The reverse holds true. When selling pressure dominates (massive profit-taking, SSR lifted, dilution announced), price can drop as fast as it rose. I've seen stocks with 0.53M float run +116% intraday and close flat the next day. The mechanism doesn't distinguish direction—it amplifies the excess, whatever it is.

SSR, dilution and structural risks

Stocks posting gaps of this magnitude generally trigger Short Sale Restriction (SSR), an SEC rule (Regulation SHO, Rule 201) that activates automatically when a stock falls 10% or more from the prior close. Once SSR is in place, short sales can only be executed above the best bid (ask), limiting aggressive selling pressure.

SSR remains active for the rest of the session and the following session. All three stocks from September 24 likely triggered SSR during their climb or the subsequent consolidation, depending on their intraday trajectory.

Dilution remains the major structural risk. Small-caps with tight floats often have a history of repeated share issuances to fund operations (cash burn). Every new issuance increases outstanding shares, dilutes existing shareholders, and changes the float. FloatVerify tracks this data in real time and displays the annualized dilution rate (shares issued over trailing 12 months / total shares) to quantify this risk.

A spectacular gap says nothing about a company's intrinsic value. It reflects a temporary imbalance between supply and demand on a restricted float. Whether this move will hold depends on external factors (catalysts, results, upcoming dilution) that FloatVerify doesn't predict—it measures what is, not what will be.

Why these stocks and not others?

No specific catalyst is established here for APUS, SRZN or PFSA. FloatVerify reports measured moves without attributing undocumented causes. Gaps can be triggered by:

• Clinical trial results announcement (biotech)
• Contract or partnership
• Regulatory change
• Media coverage
• Volume influx with no identifiable catalyst (momentum trading)

Without an SEC document or press release dated September 24, 2026, we can only observe the move, not explain it. This rigor distinguishes FloatVerify from platforms that extrapolate causes from fragile correlations. You see the numbers; you judge what they mean.

Where this data comes from

FloatVerify compiles float data from primary sources:

• SEC EDGAR: filings 10-K, 10-Q, S-1, 424B5, 8-K
• Regulation SHO: daily list of stocks under SSR
• Market feeds: volume, price, bid/ask in real time

Every figure is dated and sourced. When two sources (for example, a 10-Q filing and a 424B5 prospectus) give different floats for the same company, FloatVerify displays both with their respective dates. This transparency lets you judge the freshness and reliability of a figure, rather than taking it as given.

Recap

Point	Takeaway
Biggest gap	APUS +205% (float 1.51M, volume 53.4M, ratio ~35x)
Second place	SRZN +89% (float 11.75M, volume 7.7M)
Third place	PFSA +71% (float 0.53M, volume 36.6M, ratio ~69x)
Key mechanism	Tight float + heavy volume = concentrated price pressure and amplified volatility
Primary risk	Dilution (repeated share issuances) that increases float and reduces each shareholder's stake
Data source	SEC filings (10-K, 10-Q, S-1, 424B5), Regulation SHO, market feeds
FloatVerify approach	Dated and sourced figures, display of divergences between sources (source split), no prediction

FAQ

What was the biggest small-cap gap on September 24, 2026?

APUS (Apimeds Pharmaceuticals US, Inc.) posted the largest gap at +205% on the open with an intraday peak of +272%. Its float was 1.51 million shares against 53.4 million in volume, roughly a 35x volume-to-float ratio.

Why does a low float amplify price moves?

Float represents the number of shares available for public trading. When volume trades the float multiple times in a single session, each available share changes hands repeatedly, creating concentrated buying or selling pressure that can drive significant price swings.

Where do you find the float for a US-listed small-cap?

Float is calculated from SEC filings (Forms 10-K, 10-Q, S-1, dilution effects) by subtracting shares held by insiders and affiliates from total outstanding shares. FloatVerify compiles this data and surfaces divergences between sources rather than presenting a single figure.

Does float change over time?

Yes. Every new share issuance (public offering, PIPE, warrant conversion) changes the outstanding share count and therefore the float. That's why FloatVerify dates every data point: a float measured before dilution is no longer valid after.

What does SSR (Short Sale Restriction) mean for these stocks?

SSR is triggered automatically when a stock falls 10% or more from the prior close. It prohibits shorting on the bid, limiting part of the selling pressure. All three stocks from September 24 likely triggered SSR during or after the session.

Sources

• SEC EDGAR — official database of US-listed company filings (Forms 10-K, 10-Q, S-1, 424B5, 8-K)
• Regulation SHO — short sale regulatory framework and Rule 201 (SSR)
• Referenced SEC forms: 10-K (annual report), 10-Q (quarterly report), S-1 (offering registration), 424B5 (final prospectus), 8-K (material event)
• FloatVerify — compilation of float, dilution and cash burn data from the primary sources above

See the float, sourced and dated, on FloatVerify.

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FloatVerify shows the float, dilution and cash burn of US small-caps, every number sourced and dated—and surfaces divergences between sources ("source split") instead of one falsely certain figure.

Disclaimer: FloatVerify is a data tool, not an investment advisory service. Nothing here is a recommendation to buy or sell. Data, not advice.