How to Detect Short Squeezes Using Free Public Data
Short squeeze detection is typically marketed as a premium feature on expensive institutional platforms. Services like Ortex and S3 Partners charge hundreds per month for estimated short interest data. But the underlying source data is public — FINRA publishes daily short volume and bi-monthly short interest reports, and the SEC releases Fails-to-Deliver data every two weeks. The real value is not in the raw data but in how you combine and interpret it.
The core challenge is that official short interest from FINRA is only published twice per month, on roughly the 15th and the last business day. Between reports, short interest could spike or collapse and you would not know. Daily FINRA short volume data fills this gap. Short volume represents the number of shares sold short on a given day, and the Short Volume Ratio (SVR) measures short volume as a percentage of total volume. An SVR above 50% means more than half of the day's trading involved short selling.
To estimate daily short interest between official reports, you need a cover rate model. The cover rate represents the fraction of daily short volume that gets covered (bought back) rather than held as new short positions. By calibrating this rate against actual changes in short interest between consecutive FINRA SI reports, you get a stock-specific multiplier that makes your daily estimates converge to the known values on report dates. The formula is straightforward: estimated SI today equals estimated SI yesterday plus today's short volume times (1 minus cover rate). This gives you a daily interpolated short interest estimate that anchors to official data twice a month.
SEC Fails-to-Deliver data adds another dimension. FTDs occur when a seller fails to deliver shares to the buyer within the standard settlement period. Elevated and rising FTDs often indicate that short sellers are struggling to locate shares to borrow, which increases the probability of a forced buy-in and potential squeeze. FTD momentum, measured as the trend in FTD counts over recent reporting periods, is a leading indicator of short-side stress.
The Short Pressure Score combines these signals into a single composite metric. In VolEdge, we weight SI% of float at 30%, Short Volume Ratio at 20%, Days to Cover at 20%, FTD Momentum at 15%, and Put Flow Bias at 15%. Stocks scoring above 80 with SI above 15% of float are flagged as squeeze candidates. This is not a guarantee that a squeeze will happen, but it identifies the names where the conditions are most favorable — high short interest, active short selling, rising FTDs, and bearish options positioning all converging at once.
Days to Cover deserves special attention. It measures how many days it would take for all short sellers to buy back their positions based on average daily volume. A DTC above 5 means that short covering would take a full trading week at normal volume levels. If a catalyst forces short sellers to start covering, low-float stocks with high DTC can see explosive moves because there simply are not enough shares trading to absorb the demand quickly.
The practical application for options traders is powerful. When short pressure is elevated and IV is also high, the options market is pricing in the possibility of a large move. If you believe a squeeze is likely, buying calls or call debit spreads gives you defined-risk exposure to the upside. If you think the shorts are right and the stock will decline, put credit spreads collect elevated premium. Either way, combining short pressure data with IV analytics gives you a more complete picture than either dataset alone.
VolEdge's Short Pressure Scanner runs this analysis across 150+ stocks continuously, ranking them by composite score. Free users see the top 5 results. Pro users get the full scanner with expandable rows showing 90-day short interest history, calibrated cover rates, and score breakdowns. No Ortex subscription required.