Biggest Small-Cap Gaps 2026-09-04: Float and Dilution Sourced

Direct answer: The September 4, 2026 session recorded four notable small-cap gaps: IMRN (+78% intraday, 8.07 million float), TANH (+70% intraday with a +4434% opening gap, 14.43 million float), WETO (+34% intraday, 82.08 million float), and YMT (+26% intraday, 7.63 million float). These moves reflect the mechanical impact of heavy volume on a restricted share pool, without prejudging the origin or durability of each gap.

Four notable moves from the session

On September 4, 2026, four US-listed small-caps posted significant intraday swings. FloatVerify consolidated market data and SEC filings to establish the following table:

Ticker	Max intraday gap	Opening gap	Float (millions)	Closing price	Volume
IMRN	+78%	+63%	8.07	$1.7701	64,498,561
TANH	+70%	+4434%	14.43	$22.43	59,878
WETO	+34%	+124%	82.08	$2.55	12,696,778
YMT	+26%	+46%	7.63	$2.82	256,933

IMRN (Immuron Limited) posted the largest intraday gap in absolute percentage terms: +78%. The stock opened +63% above the prior close, then climbed further. Observed volume: 64.5 million shares on an 8.07 million float—roughly 8x the available share pool. That ratio translates to massive rotation: theoretically, each share changed hands eight times during the day, which mechanically amplifies volatility.

TANH (Tantech Holdings Ltd.) shows an exceptional opening gap of +4434%. That kind of number usually signals a recent reverse split, merger, or other structural corporate event. Without a specific catalyst in the raw data, you can't attribute this gap to a single cause. On a gapping small-cap, checking the prior days' 8-K filings becomes reflex—a 1-for-50 reverse split can produce this sort of apparent jump. The intraday gap measures +70% from the adjusted open, with volume of 59,878 shares on a 14.43 million float.

WETO (Wetour Robotics Limited) opened +124% above the prior close and finished the day +34% higher. Volume: 12.7 million shares on an 82.08 million float, roughly 15% of the pool. Moderate ratio, but the opening gap testifies to a marked supply-demand imbalance at the start of the session. When offers are scarce on the order book, even moderate volume can move price brutally.

YMT (Yimutian Inc.) closed +26% above the prior session, with a +46% open. Float of 7.63 million, volume of 256,933 shares (about 3% of float). Less intense in rotation, but marked enough to make the recap.

No specific fundamental catalyst (earnings release, contract, FDA approval, merger) is provided here. That doesn't mean one doesn't exist, but it must be verified in SEC filings and official releases before drawing conclusions.

The thin-float, heavy-volume mechanism

Float—the number of shares actually available for public trading, excluding insider lock-ups and regulatory restrictions—plays a mechanical role in price swing amplitude. Thin float + heavy volume = heightened sensitivity. Each buy or sell carries more weight when the pool of available shares is restricted. Sustained demand flow can push price up fast; conversely, seller flow can drop it.

The volume/float ratio is a useful proxy for estimating this mechanical pressure. When a day's volume represents 100% of float or more, that means on average each share changed hands once. In reality, some shares turn over multiple times, others not at all. The higher the ratio, the more intense the rotation.

IMRN traded 64.5 million shares on an 8.07 million float, a volume/float ratio of roughly 8x. In theory, each float share traded eight times during the day. In practice, part of the float didn't move (passive holders, unaccounted lock-ups). Active shares therefore turned over even more frequently. This massive rotation mechanically amplifies volatility.

Conversely, YMT traded 256,933 shares on a 7.63 million float (about 3%). The +26% intraday gap occurred with moderate rotation, suggesting either a concentrated supply-demand imbalance (few offers on the book) or large block transactions.

This mechanism says nothing about direction of movement (up or down) or sustainability. It describes only the mechanical price sensitivity to a given volume flow. Direction depends on supply-demand balance; sustainability depends on the underlying catalyst and float structure (lock-ups, coming dilution, regulatory restrictions).

Sourced and dated float: a moving figure

Float is not a constant. It shifts with every dilution (PIPE issuance, ATM program, warrant exercise, convertible conversion) and every contractual unlock (expired lock-up, lifted affiliate restrictions). A float measured in February can be stale by September if the issuer raised capital in between.

Primary sources for reconstructing float are SEC filings:

• Forms S-1, 424B (prospectuses): indicate the number of shares registered for public sale, insider contractual lock-ups, and initial capital structure.
• Forms 10-K, 10-Q (quarterly and annual reports): provide total shares outstanding as of a given date.
• Forms SC 13D/G: detail holdings above 5% and identify affiliates subject to restrictions.
• Forms 8-K: announce material events (dilution, reverse split, merger) that alter float.

Float is therefore dated: it corresponds to the capital state at a specific date, and must be recalculated after each dilutive event. A reliable data tool displays not just the figure but also its update date and calculation source (prospectus, 10-Q, etc.). FloatVerify goes further by displaying divergences between sources ("source split") when multiple filings give different figures, instead of presenting a single falsely certain number.

Regulation SHO and SSR: the role of short-sale restrictions

When a small-cap stock posts a +78% or +70% intraday gap, it often triggers the SSR (Short Sale Restriction) rule from the SEC's Regulation SHO. Automatic trigger: the stock loses 10% or more from the prior close. Consequence: prohibition on shorting at the best bid price for the rest of the day and the following day. Short sellers can still sell, but only at the best bid or above (uptick rule).

Why does this matter? SSR reduces immediate sell pressure by forcing shorts to wait for an uptick, which can slow a stock's free fall. It doesn't block short sales, and it doesn't prevent a stock from continuing to decline if sell pressure is sufficient.

In the case of the September 4, 2026 bullish gaps, SSR probably wasn't active at the open (since the stocks were rising), but it can trigger later in the day if a sharp reversal causes a 10%+ drop from the prior close. Traders track SSR status via the daily public file published by the exchanges (NYSE, Nasdaq).

SSR doesn't explain bullish gaps. It influences market dynamics once the gap is established: if the stock reverses and loses 10%, SSR mechanically brakes shorts, which can limit correction amplitude.

Dilution and warrants: the structural risk of small-caps

Small-caps frequently raise capital via PIPEs (Private Investment in Public Equity), ATM (At-The-Market) programs, or warrant issuances. Each issuance increases shares outstanding and mechanically reduces each existing shareholder's percentage ownership (dilution).

Warrants play a particular role: they give the holder the right (but not the obligation) to buy shares at a fixed price (strike) during a given period. Market price above strike? Warrants become "in the money" and their exercise becomes likely. Each exercise creates new shares and increases float.

Theoretical example: an issuer with 10 million shares outstanding and 5 million exercisable warrants at $2 will see its float increase 50% if all warrants are exercised (moving to 15 million shares). Effective float therefore depends not only on existing shares but also on outstanding dilutive instruments (warrants, options, convertibles).

Investors can identify these instruments in prospectuses (S-1, 424B) and quarterly reports (10-Q), "Equity and Dilution" section. An 8 million float today can become 12 million tomorrow if 4 million warrants are exercised. Float must therefore be dated and sourced: an isolated figure without an update date is unusable.

Where to read this data and how to cross-check

Float, dilution, and volume data are read across several complementary sources:

1. SEC EDGAR (sec.gov/edgar): public database of all mandatory filings from US-listed issuers. Search by ticker to access forms S-1, 10-K, 10-Q, 8-K, SC 13D/G.
2. Prospectus forms (S-1, 424B): initial capital structure, insider lock-ups, issued warrants.
3. Quarterly and annual reports (10-K, 10-Q): total shares outstanding, recent dilution, outstanding dilutive instruments.
4. Forms 8-K: material events (PIPE, reverse split, massive warrant exercise).
5. Public SSR files (Nasdaq, NYSE): daily list of stocks subject to SSR.

A reliable data tool like FloatVerify automates this collection and consolidates figures by displaying the source and date of each data point. When multiple sources give contradictory figures (e.g., a 10-Q indicates 10M shares but a recent 8-K announces dilution not yet reflected in the 10-Q), FloatVerify displays both figures and the divergence ("source split") instead of choosing arbitrarily.

Recap

Point	Takeaway
Four notable gaps on 2026-09-04	IMRN +78%, TANH +70% (+4434% opening gap), WETO +34%, YMT +26%.
Float and volume	IMRN: volume 8x float; TANH, WETO, YMT: more moderate ratios. The volume/float ratio is a mechanical proxy for price pressure.
Dated and sourced float	Float evolves with every dilution (PIPE, ATM, exercised warrants). A stale figure misleads. Always verify date and source (prospectus, 10-Q, 8-K).
Regulation SHO and SSR	SSR triggers automatically after a 10%+ drop and brakes short sales. It doesn't explain bullish gaps but influences correction dynamics.
Dilution and warrants	Exercised warrants increase float. An 8M float today can become 12M tomorrow. Read prospectuses and 10-Qs to identify outstanding dilutive instruments.
Primary sources	SEC EDGAR (sec.gov/edgar), forms S-1, 424B, 10-K, 10-Q, 8-K, SC 13D/G. Cross-check sources to detect divergences.

FAQ

What were the biggest small-cap gaps on 2026-09-04?

The four most notable moves were IMRN (+78% intraday, 8.07M float), TANH (+70% intraday with an extreme +4434% opening gap, 14.43M float), WETO (+34% intraday, 82.08M float), and YMT (+26% intraday, 7.63M float). All showed significant volume relative to their float.

What is float and why does it matter for understanding these gaps?

Float is the number of shares actually available for public trading, excluding insider lock-ups and regulatory restrictions. A thin float paired with heavy volume creates mechanical price pressure: each buy or sell carries more weight when the pool of available shares is limited. Float is a dated figure that changes with every dilution or unlock.

Where do you find a small-cap's float and how do you verify it's current?

Float is reconstructed from SEC filings (forms S-1, 424B, 10-K, 10-Q, SC 13D/G). Total shares outstanding appear in quarterly and annual reports; locked holdings (insiders, affiliates, lock-up agreements) are listed in prospectuses and 13D/G filings. Float = shares outstanding - locked shares. Since these figures shift with every dilution (PIPE, ATM, exercised warrants), a February float can be stale by September.

Why does TANH show a +4434% opening gap?

An opening gap in the thousands of percent usually signals a recent reverse split or structural corporate event (merger, spin-off, massive unlock). Without a specific catalyst in the data, you can't pin this gap to a single cause; you need to check the issuer's SEC filings to identify the exact transaction. The figure underscores the importance of cross-checking sources and dating every data point.

Is the volume-to-float ratio a reliable volatility indicator?

It's a useful mechanical proxy but incomplete. A high volume/float ratio (say 5x or 10x the float traded in a day) means each share changed hands multiple times and buyer or seller pressure can move price fast. That said, the ratio says nothing about direction, catalyst, or actual order book depth. Always combine it with regulatory restrictions (SSR), contractual lock-ups, and dilution data for the full picture.

Sources

• SEC EDGAR (sec.gov/edgar): public database of mandatory filings from US-listed issuers.
• Forms S-1, 424B: IPO and public offering prospectuses, detailing initial capital structure and lock-ups.
• Forms 10-K, 10-Q: annual and quarterly reports providing shares outstanding and dilutive instruments.
• Forms 8-K: material event announcements (dilution, reverse split, warrant exercise).
• Forms SC 13D/G: declarations of holdings above 5%, identifying affiliates and restrictions.
• Regulation SHO (sec.gov): SEC rule governing short sales and the SSR (Short Sale Restriction).
• Public SSR files: daily lists published by Nasdaq and NYSE of stocks subject to SSR.

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.