Low Float Stock Scanner
What It Actually Does (And Doesn't)

What Is a Low-Float Stock Scanner?

A low-float stock scanner is a piece of software that continuously scans every ticker on the US exchanges and OTC markets, then filters out everything except stocks with a small tradable share count. "Float" refers to the shares actually available for public trading - not the total shares a company has issued. A company can have 200 million shares outstanding but only 8 million in the float if insiders, funds, or a lockup agreement hold the rest.

Because there are fewer shares to go around, low-float stocks can move fast when buying or selling volume spikes. A scanner's job is to catch that spike early - usually by checking float size alongside relative volume, price change, and sometimes news or halts - and send an alert. Some scanners run manually inside a trading platform. Others, like rules-based alert services, run automatically in the background and email or text you when a stock clears every condition.

Why Float Size Changes How a Stock Trades

Float size matters because it directly affects supply and demand math. When 5 million shares are available and buy orders suddenly outnumber sellers, the price has to move a lot to find a new equilibrium. With a 500-million-share float, the same dollar amount of buying barely moves the needle. This is the mechanical reason low-float names show bigger percentage swings, both up and down, than large-cap stocks.

It also means these stocks are thinner - wider bid/ask spreads, more slippage on market orders, and a higher chance of a halt if volatility triggers exchange circuit breakers. None of that is inherently good or bad; it's just a different risk profile than a mega-cap. If you want the full mechanics of how float is calculated and why it differs from shares outstanding, see this low-float explainer.

The Core Filters Most Scanners Run

Not every scanner uses the same criteria, but most low-float tools are built around some combination of the following filters:

• Float size - typically under 10-20 million shares, sometimes tighter
• Relative volume - today's volume compared to the stock's normal average
• Price range - many scanners exclude sub-penny stocks or cap the price to stay in a specific risk band
• Percentage change - a minimum move up or down over a set window
• News or catalyst presence - a press release, filing, or halt that could explain the volume
• Market cap - filtering out companies too small to have any real liquidity

A rules-based scanner only sends an alert when a stock clears every condition on its checklist, not just one or two. That's the difference between a screener you scroll through manually and an actual alert system - the former shows you a list, the latter tells you when something specific and repeatable has already happened.

Build Your Own Scanner vs. Use a Paid Service

You can build a basic low-float scanner yourself using free or low-cost screener tools from most brokers, then manually check float, volume, and news each time something trips your filters. This works fine if you have time to sit at a screen and don't mind doing your own verification on every hit.

Paid alert services exist because most people don't have that time, and because a well-built rules engine can check eight conditions across thousands of tickers every 15 minutes - something no human can do by hand across the whole market. The tradeoff is you're trusting someone else's rules and, often, their marketing. Before paying for any service, check whether they publish real, dated alert history rather than cherry-picked screenshots. This alert-services comparison walks through what to look for.

Risks You Can't Filter Out

No scanner, no matter how many conditions it checks, removes the underlying risk of trading low-float stocks. A few things worth knowing before you rely on any alert:

• Low-float stocks can gap or halt violently in either direction with no warning
• Companies with small floats often have weak fundamentals and can dilute shares (issue more stock) shortly after a run-up, which tanks the price
• Wide spreads mean your actual fill price can differ meaningfully from the last quoted price
• A scanner alert tells you a stock matched a pattern historically associated with movement - it is not a prediction and not a signal to act

Anyone using a low-float scanner should treat it as a research starting point, not a signal to trade off of blindly. This content is for education only and isn't financial advice.

How to Judge Any Scanner's Track Record

The single best way to evaluate a scanner or alert service is to look at its published history, warts and all. Anyone can show you their five best trades. Far fewer will show you every alert, including the ones that lost money. If a service only posts winners, that's a red flag, not proof of skill.

Ask three questions before trusting any scanner's claims: Is the log timestamped and unfiltered? Does it include losers? Can you verify the entry price against public market data? A scanner that can't answer yes to all three isn't giving you enough information to judge whether its rules actually work.

Where Ignition Fits

Ignition Alerts is a rules-based scanner that checks the entire US market every 15 minutes for low-float, micro-cap stocks and only emails an alert when a stock clears all eight of its conditions - float size, volume, price action, and a few others it doesn't hide. It's built as a tool to flag setups worth researching further, not a signal service that tells you what to do with your money.

The reason it's worth mentioning here at all is transparency: every alert, win or loss, is published in the complete public track record, and the logic behind the rules is explained in plain language on the how the method works page. 25 alerts have exceeded +100% to date (best: MTEN +765% from $1.1) - full unfiltered log at https://ignitionalerts.com/performance.html. Past alerts, including that one, say nothing about what happens with the next one - low-float stocks are volatile in both directions, and this is educational information, not a recommendation to buy or sell anything.

Risk disclaimer: low-float and micro-cap stocks are among the most volatile, illiquid securities in the market; total loss is possible and nothing in this article is financial advice. Ignition Alerts is a research tool - it never tells you to buy or sell. Read the full risk disclosure.

Frequently asked questions

What share count counts as a low float?

There's no single legal definition, but most scanners and traders consider anything under 10-20 million shares in the tradable float to be low float. Some tighten that further to under 5 million for what's sometimes called a micro-float. The exact cutoff varies by tool and by strategy.

Are low float stocks riskier than large-cap stocks?

Generally yes, in the sense that price swings tend to be larger and faster in both directions. Thin trading volume, wide spreads, and higher dilution risk all add to that. This isn't a reason to avoid them outright, but it does mean position sizing and risk awareness matter more than with a heavily traded large-cap name.

Can a scanner guarantee a stock will keep moving after an alert?

No. A scanner alert only confirms that a stock matched a specific set of historical conditions at a specific moment - it says nothing about what happens next. Markets are unpredictable, and past pattern matches don't guarantee future results.

How often should a low-float scanner refresh?

It depends on your goals, but many rules-based scanners refresh every 15 minutes during market hours to catch volume and price shifts as they build, rather than waiting for end-of-day data. Faster refresh rates matter more for intraday setups than for longer-term research.

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