Short Interest

What days to cover actually measures

Days to cover is the short position divided by the security's average daily trading volume. It answers one question: if every short seller decided to buy back at once, and they were the only buyers, how many full trading days would that take?

That framing is the whole point. A position of ten million shares means nothing by itself — it is enormous in a security that trades two hundred thousand shares a day and trivial in one that trades forty million. The ratio is what makes two securities comparable.

It is also the mechanism behind a squeeze, which is why the metric gets attention. When the number is large, the shorts cannot exit without being the dominant buyer for days on end, and their own buying pushes the price against them. When it is one or two, they can be out by lunchtime and nothing is crowded about the position.

Three measurements, one word

“Short” gets used for three datasets that do not measure the same thing, and reading one as another produces confident nonsense.

• Short interest — this page. A balance: shares borrowed, sold, and not yet bought back, as of a settlement date. Reported twice a month.
• Short volume — a flow. Trades flagged short on the day they execute. Most of it is a market maker shorting to fill your buy order and flattening minutes later, which is why the market-wide median sits near half and means nothing.
• Fails to deliver — a settlement break. Shares that did not arrive on time. Overwhelmingly operational, and explicitly not evidence of naked shorting.

A security can be high on one and low on the others. Reading them together is the only way any of them is informative.

Why this page does not show percent of float

Percent of float is the number most sites lead with, and it is the number we cannot honestly print. Float — shares actually available to trade, after insiders and restricted holdings — is not in any filing. Every float figure in circulation is a commercial vendor's estimate, they disagree with each other by material amounts, and they are licensed. Publishing one here would mean republishing a vendor's proprietary estimate as though it were the regulatory filing it sits next to.

Days to cover uses FINRA's own average-volume figure from the same file, so every number on this page comes from the one source.

Limits worth stating

• It lags. Positions are as of a settlement date roughly a week before publication, and the file arrives twice a month. In a fast-moving name the real position has already changed.
• Volume is FINRA's, not the consolidated tape. For a security whose trading is mostly on a foreign primary listing, the US average volume understates reality and days to cover comes out far too high. Several perennial members of this list are exactly that case rather than crowded shorts.
• A position is not a view. A large short can be one leg of a convertible-arbitrage or merger-arbitrage trade, or an index hedge, with no directional opinion attached at all.
• Zero-volume securities are dropped. FINRA writes a sentinel value where average volume is zero; it is stored as no value rather than as an enormous days-to-cover figure.

Where this comes from

FINRA publishes a consolidated short interest file twice a month, free and public, covering every equity security its members report. It is parsed here directly. Each security's own page pulls this together with its filings, ownership and settlement fails — see any ticker under security pages, or the rest of the Markets section.