What is Short interest?
In short
The number of shares sold short and not yet covered, often shown as a % of float. Published twice a month in the US.
Also known as: days to cover, short squeeze
Short interest is the number of shares that have been sold short and not yet bought back (covered). It is often shown as a percentage of the float, the shares available for public trading. In the US, brokers report it to FINRA and it is published twice a month with some delay.
Key metrics
- Short interest % = shares sold short ÷ float × 100%
- Days to cover = shares sold short ÷ average daily volume. Roughly how many days of trading it would take for all shorts to cover.
How to read it
High short interest means many investors expect the stock to fall — sometimes pointing to real problems in the company. On the other hand, it is also future buying power: if good news hits, shorts are forced to buy at the same time and a short squeeze can follow. The higher the days to cover, the sharper a squeeze can be.
Limitations: the data is published with a lag, so it doesn't fully reflect the current situation. High short interest by itself is neither a "sell" nor a "buy" signal — it's just one piece of market sentiment.
Example
Illustrative: a stock has a float of 60M shares, 12M shares sold short and average daily volume of 3M.
- Short interest: 12 ÷ 60 = 20% of float.
- Days to cover: 12 ÷ 3 = 4 days.
Another stock: float 200M, short 6M (3%), daily volume 10M → days to cover 0.6. Squeeze risk is far higher in the first stock.
Mistakes and tips
Check the short interest date: the data is several days old and things may have changed.
Don't buy just because high short interest 'means a squeeze' — often the shorts turn out to be right.
Watch short interest together with relative volume and news — squeezes usually start with a catalyst and a volume spike.
Frequently asked questions
- What short interest is considered high?
- There's no hard line, but above 10% of float is often seen as high and above 20% as very high.
- Where does short interest data come from?
- In the US brokers report to FINRA; the data is published twice a month and shown on financial websites.
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Related terms
Read more on this
- Short interest: what short positions tell you (and is shorting halal?)What short interest and days to cover mean, how to read FINRA data, what it doesn't tell you — and what scholars say about short selling.
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