ORTEX short interest data: live estimates, methodology and API.
Exchanges publish short interest twice a month, roughly seven business days after the positions settle, so the official print is up to four weeks old by the time the next one arrives. ORTEX models it from securities-lending data and updates the estimate through the trading day, alongside the cost to borrow (borrow fee), availability, utilization and days to cover. These are the estimates professional desks work from and the financial press quotes.
See the data itself
- Short interest overview →Most-shorted stocks, short extremes, short changes and sector averages
- ORTEX Short Index →Market-wide short positioning
Example stocks: AAPL short interest · TSLA short interest · NVDA short interest · GME short interest
Short interest
Daily and intraday short interest, cost to borrow and utilization for more than 52,000 securities.
ORTEX has estimated short interest every trading day since 2012. Official figures arrive twice a month and around eleven days late. ORTEX publishes a daily estimate for more than 52,000 securities before the US open, updates it through the session, and puts a confidence range on every number. Cost to borrow, utilization, days to cover, availability and the positions disclosed to regulators sit alongside it, so the whole short side of a stock is one dataset.
of ORTEX estimates were within one percentage point of free float of the official figure, across 2.1 million official prints in the US, Canada, Australia and Hong Kong since August 2023.
Measured against every exchange-reported settlement figure. Estimate frozen before the official print.
See squeeze risk building on longs and shorts, weeks before the official print.
Fourteen years of daily, point-in-time short data for factor and event research.
Cost to borrow and availability to size, finance and time a short.
The whole short side, in one dataset
Every number a short book, a risk desk or a squeeze screen needs, on one row per stock per day.
Shares short every day, as a percentage of free float and in dollar value, with upper and lower confidence bounds. A daily read between official report dates.
Short interest re-estimated through the session as lending moves, for around 15,800 US securities, with a live snapshot for any stock.
The ORTEX cost to borrow for new loans and for all loans. The clearest single measure of how hard a stock is to short, and when that is changing.
Shares on loan, the share of lendable supply in use and its daily change, and the shares still available to borrow.
More than 600,000 positions disclosed to 14 regulators in Europe, the UK and Japan since 2003: who is short, how much, and since when.
Days to cover over four volume windows, and one 0 to 100 score that ranks a whole market by short-side pressure.
Official short interest is late and infrequent; lending data on its own is noisy. ORTEX combines both into one daily estimate with a confidence range, removes dividend-driven lending that is not short selling, and scores itself against every official print.
Estimate vs official print
The daily ORTEX estimate against every official FINRA figure for one US stock through a fourfold rise in short interest.
- Official data
- Twice a month, around eleven days after settlement
- ORTEX
- Every trading day before the open, plus intraday
- The move
- 31m shares short in September 2025 to 140m by December
While short interest in BYND quadrupled, the ORTEX line showed each step up to two weeks before the official figure.
The line was published every morning. Each dot is the official figure, which arrived around eleven days after its settlement date. September 2025 to July 2026, before the company's 2026 reverse split.
The metrics, defined
More terms, from free float to short squeezes, in the short interest glossary.
Shares sold short as a percentage of the free float, the shares actually available to trade. ORTEX estimates it from securities-lending data and updates it through the trading day, instead of waiting for the twice-monthly exchange snapshot.
The annualized fee to borrow shares for short selling. A rising borrow fee means the lending market is tightening; an expensive borrow makes shorts costly to hold.
Shares still available to borrow, relative to shares already borrowed. As availability dries up toward zero, new shorts cannot be opened and existing shorts get harder to maintain, a classic squeeze ingredient.
The share of lendable stock currently out on loan. High utilization plus a rising borrow fee is a crowded short.
Short interest divided by average daily volume: roughly how many trading days short sellers would need to buy everything back.
Reading a squeeze setup
The ingredients tend to appear together: high short interest as a percentage of free float, shrinking availability, expensive borrow and high days to cover. When a catalyst hits a stock in that state, short sellers all need the same exit at the same time. ORTEX data made that setup visible before the Beyond Meat squeeze in October 2025, when Reuters cited ORTEX estimates of short interest above 100% of the public float.
Short interest and borrow figures are ORTEX estimates produced by our models, not exchange or regulatory filings. Estimates revise as new lending data arrives.
How fast a short squeeze moves
Faster than the official data. GameStop went from about $17 to an intraday $483 in under three weeks in January 2021, starting from short interest that the SEC’s own staff report later put above 100% of the public float. The whole move fit inside a single twice-monthly reporting cycle.
AMC did it twice the same year. In January 2021 the shares ran from about $2 to $20 in three weeks. The June echo was faster still: from roughly $12 to an intraday $72.62 in seven trading sessions, a move that cost funds on the short side more than a billion dollars in a single week.
The record belongs to Volkswagen in October 2008. Porsche disclosed control of about 74% of the shares on a Sunday; with the state of Lower Saxony holding another 20%, short sellers sitting on roughly 12% of the stock were left chasing a free float of about 6%. The price went from around €210 to an intraday €1,005 in the two trading days that followed, briefly making Volkswagen the most valuable company in the world. That is the five-fold move sketched in the chart above.
None of those moves waited for an exchange print. Live estimates are the only way to see the setup while it is still building, and the unwind while it is still tradeable.
On the platform, in your code, in your models
Everything on this page is live on the ORTEX platform and ships raw over the REST API, Python SDK and Excel add-in, from single-stock queries to full-universe bulk files.
And the data earns its keep beyond squeeze watching. Our Short Momentum Stock Score trading model, built partly on this short interest data, returned 2,458% over the last 16.80 years, against 817% for the S&P 500 Total Return. That is 2.8× the index, compounding at 21.3% a year.
Get the same data your desk quotes.
Live short interest on the platform, over the REST API and Python SDK, or straight into Excel. Start free, no card required.
See also: Stock Scores, Index Rebalance forecasts and the ORTEX API.