Short Interest Tracking Reference
Direct answer: Short interest is the number of shares sold short that have not yet been covered (bought back). It is reported twice monthly by FINRA. Key metrics: Short Interest Ratio (days to cover) = short interest divided by average daily volume. Short Interest as % of float above 20% is considered high; above 40% is extreme. High short interest can signal bearish consensus or potential short squeeze.
Short Interest Key Metrics
| Metric | Definition | Threshold (approximate) |
|---|---|---|
| Short Interest (shares) | Total shares currently sold short and not yet covered | Compare to float and average volume |
| Short Interest % of Float | Short shares divided by total float shares | High: above 15%; Extreme: above 40% |
| Short Interest Ratio (Days to Cover) | Short shares divided by average daily volume | High: above 5 days; Extreme: above 20 days |
| Short Squeeze Potential | High % float + high days-to-cover + increasing short interest | Short squeeze risk: all three elevated simultaneously |
| FINRA reporting frequency | Twice per month (mid-month and month-end, published approximately 1 week later) | Data has 1-2 week lag |
Source: FINRA: Short Interest Data. Last verified: September 2026.
Frequently asked questions
What is a short squeeze and how does it happen?
A short squeeze is a rapid price increase triggered when short sellers are forced to buy back shares to cover losses, which itself drives prices higher, forcing more short covering. Mechanics: (1) highly shorted stock begins rising (for any reason -- good news, random buying, social media attention); (2) short sellers face growing losses; (3) those with margin accounts face margin calls requiring them to close shorts; (4) forced buying pushes price higher; (5) other short sellers see the price rising and rush to cover before losses grow; (6) cascade of buying accelerates the price spike. Famous squeezes: GameStop (2021, from approximately $20 to $483 in 2 weeks), Volkswagen (2008, briefly the world's most valuable company). Squeezes are unpredictable in timing and magnitude.
Where can investors find current short interest data?
Free short interest data sources: FINRA's short interest database (finra-markets.morningstar.com) publishes bi-monthly data for all exchange-listed stocks. Major financial sites (Nasdaq.com, Barchart.com, MarketWatch) republish FINRA data with additional metrics. Paid sources for real-time data: S3 Partners (institutional), Ortex (popular with retail short-squeeze traders), IHS Markit (institutional). The key limitation of FINRA data: it has a 1-2 week lag. For fast-moving short squeezes (like GameStop 2021), lagged data is nearly useless. Real-time borrow fee data (cost to borrow shares for short selling) is also available from prime brokers and platforms like Interactive Brokers.
Does high short interest predict negative returns?
Academic research (Dechow et al. 2001, Asquith et al. 2005) shows stocks with the highest short interest underperform those with the lowest, suggesting short sellers are on average correct in identifying overvalued stocks. However, the effect is noisy: many highly shorted stocks do fall, but some generate enormous short squeezes (GameStop, AMC, Bed Bath and Beyond). Short interest is informative but not predictive enough to drive trading decisions alone. High short interest combined with improving fundamentals (a catalyst that could force covering) is more actionable than high short interest alone. Retail traders should be very cautious about short squeeze plays -- squeeze timing is unpredictable, stocks can remain heavily shorted for years without squeezing.