Float and short interest, explained properly

Outstanding, float, and the difference

Shares outstanding is every share the company has issued and that remains issued — the number used to compute market capitalisation. You'll find it on the cover page of any 10-Q or 10-K, stated as of a recent date.

Public float is the portion of those shares that is actually available to trade in the open market. It excludes shares that are restricted or closely held:

• Shares held by officers and directors
• Shares held by affiliates — broadly, holders of more than 10%
• Restricted stock that hasn't satisfied its holding period
• Shares subject to a lock-up agreement after an IPO or a financing

In a micro-cap the gap is frequently enormous. A company can report 60 million shares outstanding while insiders and a private-placement investor hold 45 million of them, leaving a 15-million-share float. Market cap is computed off the 60 million; the price is set by the 15 million.

Why float size changes behaviour

Price is set at the margin by whoever is willing to transact right now. Float determines how much stock is standing there to absorb an order.

Consider two companies, both with genuine news that attracts $3 million of buying in an afternoon:

Company A doesn't have better news. It has fewer sellers. The same demand meets a fraction of the supply, so the price has to travel further to find people willing to part with stock. That is the entire mechanism behind "low float runners."

The symmetry is the part people forget: the same thinness that produces a 90% day produces the 50% retracement the following morning, because there is equally little bid standing underneath. Low float is not a bullish attribute. It is a volatility attribute.

Rough conventions — not rules, and vendors differ:

Float is a moving target

This is the single most expensive misunderstanding in micro-cap trading. People screen for a 4-million-share float, buy the thinness, and never check whether that number is still true — or about to stop being true.

Float grows when:

• The company sells shares. A registered direct offering or an at-the-market programme puts new, freely tradable stock into the market. An active ATM can quietly add millions of shares over weeks.
• Warrants are exercised. Most small-cap financings attach warrants. When the stock runs above the exercise price, those warrants convert into new float — precisely during the rally.
• Convertible notes convert. Notes that convert at a discount to market price create more shares the lower the price goes, which is why this structure is so corrosive.
• A resale registration goes effective. An S-1 or S-3 registering shares on behalf of existing holders doesn't raise the company a dollar — it converts restricted shares into sellable ones. Float can double overnight with no press release.
• A lock-up expires. Insider and pre-IPO stock becomes sellable on a known date.

And float shrinks on a reverse split — along with everything else. A 1-for-20 reverse split turns a 40-million-share float into 2 million shares. Screeners will show a brand-new "low float" stock; nothing about the business has changed, and in small caps a reverse split is very often the precondition for the next offering.

How short interest is actually reported

Short interest is not live data, and the gap between what people assume and how it works causes real losses.

In the US, FINRA requires firms to report short positions in customer and proprietary accounts twice a month — as of the settlement date mid-month and the settlement date at month-end. FINRA then publishes the consolidated figures on a published schedule, typically around eight business days after the reporting settlement date.

The practical consequence:

• The number you're looking at describes a position that existed one to three weeks ago.
• If a stock doubled last week, the short interest on your screen predates the move entirely.
• Shorts may already have covered — or piled in — and the report will not tell you for another two weeks.

Some vendors sell estimated daily short data derived from securities-lending markets. That's genuinely more current, but it measures borrowing activity rather than reported short interest, and it's an estimate. Know which of the two you're looking at before you trade on it.

Percent of float, days to cover, and utilisation

Three derived figures do most of the work:

Short interest as a percent of float

Shares short divided by float. It tells you how crowded the short side is relative to available supply. Above roughly 20% of float is heavily shorted; above 30% is unusual and tends to mean either a widely-held conviction that the company is impaired, or a structural short related to a convertible.

Be careful: if your float estimate is wrong, this ratio is wrong by the same factor. And the denominator changes — a big offering mechanically lowers short interest as a percent of float without a single share being covered.

Days to cover (short ratio)

Shares short divided by average daily volume. If 6 million shares are short and the stock trades 600,000 a day, that's 10 days to cover: shorts collectively could not exit quickly without bidding the stock up substantially.

This is usually the more useful of the two, because it accounts for liquidity. Twenty percent of float short in a stock that trades its entire float every day is not a trapped position. Five percent short in a stock that trades 0.5% of its float a day might be.

Utilisation and borrow fee

Utilisation is the share of lendable inventory currently out on loan; the borrow fee is the annualised cost of that loan. High utilisation with a high fee — "hard to borrow" — means supply of lendable stock is scarce. It's the most current of these signals because it comes from the lending market rather than a twice-monthly filing, and a rapidly rising fee is a real-time indication that shorting is getting expensive.

What a squeeze is, and what it isn't

A short squeeze is a specific mechanism: the price rises, shorts face margin calls or unacceptable mark-to-market losses, and they buy to close. That buying is price-insensitive — it has to happen — which pushes the price higher and forces the next tier of shorts to do the same.

The conditions that make it possible are not exotic:

1. A meaningful short position relative to float
2. Low available float to buy back into
3. High days to cover, so exiting takes time
4. A catalyst that makes holding the short untenable
5. Expensive or scarce borrow, which raises the cost of waiting

Three honest caveats:

• Most heavily shorted stocks never squeeze. They are heavily shorted because the short thesis is correct. Elevated short interest is, far more often than not, a signal about the company rather than an opportunity.
• The data is stale. By the time a name appears on a "most shorted" list and gets discussed, the position it describes may be weeks old.
• Companies sell into squeezes. A small-cap whose stock triples has every incentive to file an offering into the strength — and often does so within days. New shares are exactly the supply the squeeze was missing.

Reg SHO, threshold lists and failures to deliver

Two pieces of market plumbing come up constantly in small-cap discussion, usually with more significance attached than they carry.

Regulation SHO governs short selling, including the locate requirement — a broker must have reasonable grounds to believe stock can be borrowed before executing a short sale — and the close-out requirements for persistent delivery failures. Reg SHO also contains the alternative uptick rule: if a stock falls 10% or more from the prior close, short sales are restricted to prices above the national best bid for the rest of that day and the next.

Threshold securities lists are published daily by the exchanges. A security lands on the list when failures to deliver reach a specified level relative to shares outstanding for five consecutive settlement days. It indicates a persistent settlement problem, which in small caps frequently reflects scarce borrow.

Failures to deliver data is published by the SEC twice monthly, with a lag. FTDs happen for mundane operational reasons as well as from naked shorting, and a high FTD count is not by itself evidence of manipulation. It is one data point about settlement friction, no more.

A practical checklist

Before treating float or short interest as part of a thesis:

1. Pull shares outstanding from the most recent 10-Q or 10-K cover page — not from a screener.
2. Get float from two vendors. If they disagree materially, find out why before proceeding.
3. Check for a reverse split in the last 12 months. If there was one, current float readings tell you nothing about historical behaviour.
4. Scan the filing history for S-1 and S-3 registrations, 424B prospectus supplements, and any ATM programme. Count the shares that could arrive.
5. Count warrants and convertibles outstanding, and their exercise or conversion prices, from the latest quarterly filing.
6. Note the as-of date of the short interest figure, and ask what has happened since.
7. Compute days to cover yourself, using a volume average that reflects normal conditions rather than one inflated by a single spike day.

Frequently asked questions

Can short interest exceed 100% of float?

Yes, and it does not require anything improper. The same share can be lent, sold short, bought by a new holder whose broker lends it out again, and sold short a second time. Reported short interest counts each short sale; float counts each share once. Very high readings are a sign of intense lending activity and scarce supply, not automatic proof of naked shorting.

Is a low float bullish?

No. It amplifies whatever is happening. The same mechanism that produces spectacular up days produces the collapse afterwards, and thin books make exits harder in exactly the moments you most want one.

Why do float figures differ between websites?

Because float is derived, not reported. Vendors make different judgements about which holders count as affiliates, and they update on different schedules — some lag a quarterly filing by weeks. Neither is necessarily wrong; they're measuring with different rulers.

Does high short interest mean the company is bad?

It means a number of participants are positioned for the price to fall, and it's worth finding out why. Read the bear case on its merits. Sometimes it is dilution, sometimes cash burn, sometimes a convertible-related hedge that carries no directional view at all.