Short interest is the number of a company's shares that have been sold short and not yet bought back. US brokers report it to FINRA twice a month, and FINRA publishes it seven business days after each settlement date [3][4]. Two ratios make the raw number useful: short interest as a percent of shares (how much of the stock is bet against) and days to cover (how many days of normal trading it would take short sellers to buy the shares back). As of the September 30, 2026 settlement date, DataPorium data show Wolfspeed (WOLF) as the most-shorted US stock worth more than $1 billion, with 50.7% of its shares outstanding sold short and 11.4 days to cover [1].
What is short interest?
A short sale is the sale of a stock the seller does not own. The broker lends the shares, from its own inventory, from other clients' margin accounts or from another lender, and the short seller hopes to buy them back later at a lower price and return them [6]. While the position is open, the short seller pays interest on the loan, pays any dividend the stock distributes to the lender, and must meet margin rules [6]. Because a share price can keep rising, the SEC notes that a short sale exposes the seller to potentially unlimited losses, while a buyer can lose at most what was invested [6].
Short interest adds up every open short position in a stock on one date. Across all US stocks and ETFs, DataPorium data show 56.9 billion shares sold short on September 30, 2026, up 25.3% from 45.4 billion a year earlier (September 30, 2025) [1].
How often is short interest reported?
FINRA Rule 4560 requires member firms to report short positions in all customer and proprietary accounts, in exchange-listed and over-the-counter stocks, twice a month: for a settlement date around the 15th and one at month end [3]. Reports are due by 6 p.m. Eastern Time on the second business day after the settlement date, and FINRA publishes the totals seven business days after it [3][4]. The data are always about a week and a half old when they appear.
| Settlement date | Firms report by | FINRA publishes |
|---|---|---|
| September 30, 2026 | October 2 | October 9 |
| October 15, 2026 | October 19 | October 26 |
| October 30, 2026 | November 3 | November 10 |
| November 13, 2026 | November 17 | November 24 |
| November 30, 2026 | December 2 | December 9 |
| December 15, 2026 | December 17 | December 24 |
| December 31, 2026 | January 5, 2027 | January 12, 2027 |
Source: FINRA, 2026 short interest reporting dates [3].
The schedule nearly changed in 2026. On May 1, 2026, FINRA filed a proposal to move to weekly reporting, with publication five business days after each settlement date [4]. FINRA withdrew the filing on August 5, 2026, so the twice-monthly schedule remains in place [5].
How do you read short interest: percent of float and days to cover
Short interest as a percent of float or shares outstanding
The raw share count means little on its own, so it is divided by the company's shares. The float is the shares available to trade, excluding those held by insiders and other locked-up holders; shares outstanding counts every share. Because the float is smaller, short interest as a percent of float is always higher than the same figure on shares outstanding. DataPorium's percentages use shares outstanding [1].
Most stocks are lightly shorted. The SEC staff found that short interest is often below 2.5% for large non-financial companies and below 13% for small ones, and that few stocks, if any, exceed 50% on a given date [7]. Size and percentage can point in opposite directions: Nvidia (NVDA) had the largest short position in dollar terms on September 30, 2026, 311.4 million shares worth an estimated $71.4 billion, yet that was only 1.3% of its shares outstanding [1].
Days to cover
Days to cover, also called the short interest ratio, divides short interest by average daily trading volume. Wolfspeed had 26,850,248 shares sold short on September 30, 2026 and traded an average of 2,347,797 shares a day, so 26,850,248 / 2,347,797 = 11.4 days to cover [1]. A high figure means short sellers would need many sessions of normal volume to exit, which matters when they all try to leave at once.
Which stocks are the most shorted right now?
The ten most-shorted US-listed stocks with a market value above $1 billion and average volume above 500,000 shares a day, as of September 30, 2026:
| Company | Shares short | % of shares outstanding | Days to cover | Change since Sept. 15 |
|---|---|---|---|---|
| Wolfspeed (WOLF) | 26.9 million | 50.7% | 11.4 | +2.9% |
| Capricor Therapeutics (CAPR) | 18.8 million | 41.2% | 4.5 | -4.3% |
| Ondas Holdings (ONDS) | 228.5 million | 39.3% | 3.4 | -3.6% |
| SoundHound AI (SOUN) | 158.9 million | 38.6% | 9.7 | -3.7% |
| Eos Energy Enterprises (EOSE) | 134.8 million | 37.0% | 4.7 | +12.4% |
| T1 Energy (TE) | 77.1 million | 36.3% | 3.8 | +16.6% |
| Under Armour Class A (UAA) | 65.1 million | 34.5% | 6.0 | +21.8% |
| Tripadvisor (TRIP) | 38.2 million | 32.6% | 8.7 | +7.3% |
| PureCycle Technologies (PCT) | 58.6 million | 32.5% | 9.7 | +4.2% |
| Intellia Therapeutics (NTLA) | 45.1 million | 32.2% | 9.5 | -3.4% |
Source: DataPorium Short Interest Screener, settlement date September 30, 2026, published by FINRA on October 9, 2026 [1][3]. The full ranking, with filters for market value, sector and exchange, is on the DataPorium short interest screener.
What do borrow fees add?
Short interest shows how many shares are borrowed; the lending fee shows how hard they are to borrow. The fee is an annual rate charged on the value of the borrowed shares, and it climbs when lendable shares run short. The SEC staff found that average lending fees were 1.5% from January 2007 to July 2018, and only 222 companies had a fee above 100% at any point in that period [7]. GameStop (GME) later reached that extreme: its cost to borrow topped 100% in the second quarter of 2020 and was around 25% in January 2021 [7]. A high and rising fee alongside high short interest is a sign that the trade is crowded and expensive to hold.
Does high short interest predict lower returns?
On average, somewhat, but not reliably. Short sellers are often well-informed investors, and a study of NYSE, Amex and Nasdaq stocks by Paul Asquith, Parag Pathak and Jay Ritter found that equally weighted portfolios of high-short-interest stocks generally underperformed [8]. The same study found that value-weighted portfolios, where large companies count more, did not underperform, and that results from short periods were misleading [8]. High short interest is a signal worth checking, not a forecast for any single stock.
What is a short squeeze?
A short squeeze happens when a rising price forces short sellers to buy shares to close their positions, and that buying pushes the price higher still, forcing more short sellers out [7]. High short interest, many days to cover and a small float make a squeeze more likely, because exits are crowded and few shares are for sale.
GameStop, January 2021
GameStop's short interest reached 109.26% of its shares outstanding on December 31, 2020, and 122.97% of its float in January 2021 [7]. That is possible because the same shares can be lent, sold and lent again [7]. DataPorium data show 71.2 million shares sold short on that date and 6.1 days to cover [2]. The stock closed at $347.51 on January 27, 2021, more than 1,600% above its January 11 close, and hit an intraday high of $483.00 on January 28 (prices before the company's 4-for-1 split in July 2022) [7]. Short interest fell 65.4% to 21.4 million shares by January 29 [2]. The SEC staff found that short covering contributed to some of the rise, but that it was a small fraction of buying and that positive sentiment, not buying-to-cover, sustained the rally [7]. As of September 30, 2026, 8.5% of GameStop's shares outstanding were sold short [2].
Volkswagen, October 2008
On Sunday, October 26, 2008, Porsche disclosed that it held 42.6% of Volkswagen's ordinary shares plus cash-settled options on another 31.5%, a total of 74.1%, and said there were far more short positions than expected [9]. With the state of Lower Saxony also holding a large stake, few shares were left for short sellers to buy. Volkswagen's stock rose from 211 euros at the close on Friday, October 24, to more than 1,005 euros on October 28, briefly making it the world's most valuable listed company [10].
Short interest shows how many shares are bet against a company; days to cover and borrow fees show how hard it would be for those bets to unwind.
Key takeaways
- Short interest is reported to FINRA twice a month and published seven business days after each settlement date; the September 30, 2026 data came out on October 9 [3].
- Days to cover divides shares short by average daily volume: Wolfspeed's 26.9 million shares short equaled 11.4 days of trading on September 30, 2026 [1].
- US short interest totaled 56.9 billion shares on September 30, 2026, up 25.3% in a year [1].
- High short interest has predicted weaker returns only for equally weighted portfolios, not value-weighted ones, in academic tests [8].
- GameStop's short interest peaked at 109.26% of shares outstanding on December 31, 2020, before the January 2021 squeeze took the stock to an intraday high of $483.00 [7].
Frequently asked questions
What is a high short interest percentage?
There is no official threshold, but SEC staff found short interest is usually below 2.5% for large companies and below 13% for small ones, and few stocks exceed 50% [7]. As of September 30, 2026, Wolfspeed was at 50.7% of shares outstanding [1].
How is days to cover calculated?
Divide the number of shares sold short by the average daily trading volume. 26,850,248 shares short divided by 2,347,797 shares a day gives Wolfspeed 11.4 days to cover as of September 30, 2026 [1].
When is short interest data released?
FINRA publishes it seven business days after each of the two monthly settlement dates. The October 15, 2026 data are scheduled for October 26 and the October 30 data for November 10 [3].
Can short interest be more than 100%?
Yes. When a buyer of shorted stock lends those shares out again, the same share is counted short twice. GameStop reached 109.26% of its shares outstanding on December 31, 2020 [7].
Sources & References
- [1] DataPorium Short Interest Screener (most-shorted US stocks, settlement date September 30, 2026)
- [2] DataPorium Stock Market (GameStop short interest history since 2017)
- [3] FINRA, Short Interest Reporting (2026 reporting and publication dates, accessed October 13, 2026)
- [4] SEC, Release No. 34-105482, Notice of Filing of a Proposed Rule Change to Amend FINRA Rule 4560 (May 13, 2026)
- [5] FINRA, SR-FINRA-2026-012 rule filing page and notice of withdrawal (August 5, 2026)
- [6] SEC Office of Investor Education and Assistance, Investor Bulletin: An Introduction to Short Sales (updated September 9, 2026)
- [7] SEC Staff, Staff Report on Equity and Options Market Structure Conditions in Early 2021 (October 14, 2021)
- [8] Asquith, Pathak and Ritter, Short Interest and Stock Returns, NBER Working Paper 10434 (April 2004)
- [9] Porsche SE, Porsche heads for domination agreement (press release, October 26, 2008)
- [10] Harvard Law School Forum on Corporate Governance, Market Efficiency and Limits to Arbitrage: Evidence from the Volkswagen Short Squeeze (September 15, 2021)