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Short interest is the total number of shares currently sold short and not yet covered. It is reported bi-monthly by exchanges and often expressed as a percentage of float or as days-to-cover (short interest divided by average daily volume).
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Key takeawayStocks with short interest above 25% of float carry elevated squeeze risk. Premium sellers should avoid naked calls on these names and use wider credit spreads with defined risk instead.
💡 Why It Matters
Short interest above 20% of float significantly increases the probability of short squeezes and gamma squeezes, making premium selling on these names much riskier. It also inflates put premiums, creating deceptively attractive-looking selling opportunities.
⚙ How It Works
Short interest is reported by exchanges on the 15th and last business day of each month, with a 2-day processing delay. Days-to-cover (short interest divided by average daily volume) measures how many days it would take all short sellers to cover. Values above 5 days indicate squeeze vulnerability.
📋 Example
XYZ has 28% short interest and 7 days-to-cover. IV is 65% versus 40% historical average. The 20-delta put spread pays $1.80 on $5 wings. While this looks rich, the elevated IV reflects real squeeze risk. A 30% rally would push your call spreads deep ITM if you sold both sides.
⚠ Common Mistakes
Traders sell strangles on high-short-interest stocks assuming the risk is symmetric. Short squeezes make the upside risk much larger than the downside risk. If you sell premium on these names, skew your positions toward puts only and avoid naked or spread calls.
❓ FAQ
What is Short Interest?
Short interest is the total number of shares currently sold short and not yet covered. It is reported bi-monthly by exchanges and often expressed as a percentage of float or as days-to-cover (short interest divided by average daily volume).
Why does Short Interest matter for premium sellers?
Stocks with short interest above 25% of float carry elevated squeeze risk. Premium sellers should avoid naked calls on these names and use wider credit spreads with defined risk instead.
How does Short Interest work?
Short interest is reported by exchanges on the 15th and last business day of each month, with a 2-day processing delay. Days-to-cover (short interest divided by average daily volume) measures how many days it would take all short sellers to cover. Values above 5 days indicate squeeze vulnerability.
What are common mistakes with Short Interest?
Traders sell strangles on high-short-interest stocks assuming the risk is symmetric. Short squeezes make the upside risk much larger than the downside risk. If you sell premium on these names, skew your positions toward puts only and avoid naked or spread calls.
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