When you open an options chain for the first time, two numbers in particular tend to cause confusion: volume and open interest. They appear side by side, both look like contract counts, and beginners often assume they mean the same thing. They do not — and understanding the difference is one of the most practical skills you can develop as an options trader.
Open interest is one of the clearest signals of market participation and liquidity available on any options chain. Once you understand what it measures, how it changes, and how to use it alongside volume, you will be able to select better contracts, avoid illiquid traps, and read where other traders are concentrating their positions.
Quick Answer
Open interest is the total number of options contracts that are currently active — meaning they have been opened but not yet closed, exercised, or expired.
- When a new contract is created between a buyer and a seller, open interest increases
- When an existing contract is closed or expires, open interest decreases
- Open interest resets as contracts expire, but volume resets every trading day
Higher open interest at a given strike typically means better liquidity, tighter bid-ask spreads, and easier trade execution. Low open interest means the opposite — harder to enter, harder to exit, and often at a worse price.
How Open Interest Works
Every options contract requires two parties: a buyer and a seller. Open interest tracks the net number of contracts that currently exist as active, unclosed positions in the market.
Here is how the count changes:
Opening a new position: Trader A buys one call option from Trader B, who writes (sells) it. This is a brand new contract — it did not exist before this transaction. Open interest increases by 1.
Closing a position: Trader A later sells that same call option to Trader C. Since Trader A is exiting a long position and Trader C is entering one, the total number of open contracts stays the same. Open interest does not change.
Both sides closing: If Trader A sells and Trader C happens to be closing an existing short position (not opening a new one), both sides of the trade are closed simultaneously. Open interest decreases by 1.
Exercise or expiration: When a contract is exercised or expires worthless, it is removed from the market entirely. Open interest decreases.
This is why open interest changes more gradually than volume — it only moves when contracts are genuinely created or destroyed, not every time they change hands.
Open Interest vs. Volume — The Key Difference
This is the most common source of confusion for new options traders, and it is worth being precise about.
| Metric | What It Measures | When It Resets |
|---|---|---|
| Volume | Number of contracts traded today | Resets to zero at market open every day |
| Open Interest | Total active contracts currently outstanding | Changes continuously, resets only as contracts expire |
Example: An options contract shows 8,000 in volume and 3,200 in open interest.
What does that tell you? It means 8,000 contracts changed hands today, but only 3,200 net new contracts were created. The rest were existing contracts being traded between participants who were opening, closing, or rolling positions — but not creating net new exposure.
Volume without open interest context can be misleading. A contract with high daily volume but very low open interest may simply be heavily day-traded with most positions closed by end of day — not necessarily a signal of sustained directional conviction.
The Four Open Interest and Volume Combinations
Experienced traders look at OI and volume together because the combination tells a more complete story than either metric alone.
| Volume | Open Interest | What It Likely Means |
|---|---|---|
| High | Rising | New money entering the market — bullish or bearish conviction building |
| High | Falling | Existing positions being closed — trend may be weakening |
| Low | Rising | Positions building slowly — quiet accumulation, watch for breakout |
| Low | Falling | Positions unwinding with little activity — low interest in this contract |
The most significant signal is high volume with rising open interest — it means new participants are committing capital, not just existing holders reshuffling positions. This is the combination unusual options activity trackers look for when flagging potential institutional positioning.
Why Open Interest Matters for Liquidity
Liquidity is one of the most underappreciated factors in options trading, especially for beginners. It directly affects how much you pay to enter a trade and how much you lose when you exit.
The key liquidity indicator tied to open interest is the bid-ask spread — the gap between what buyers will pay and what sellers will accept.
High open interest example:
- Strike: $100 call, 30 days out
- Open interest: 12,000 contracts
- Bid: $3.90 / Ask: $4.10
- Spread: $0.20 (5%)
Low open interest example:
- Strike: $100 call, 30 days out
- Open interest: 45 contracts
- Bid: $2.50 / Ask: $4.20
- Spread: $1.70 (68%)
In the low OI example, you pay $4.20 to buy and receive only $2.50 to sell — a built-in loss of $1.70 the moment you enter. On 1 contract (100 shares), that is $170 of immediate friction. On 10 contracts, $1,700.
This is why checking open interest before placing any options trade is non-negotiable. A contract can look attractive on premium alone but destroy value through poor liquidity.
💡 On Webull and Tastytrade, open interest is displayed directly on the options chain for every strike. Tastytrade in particular flags liquidity concerns automatically, making it easier to avoid low-OI traps before you place a trade.
How to Use Open Interest When Selecting Covered Call Strikes
For income traders selling covered calls, open interest is a practical filter — not just a theoretical concept.
When selecting a strike to sell, look for these OI characteristics:
Minimum open interest: At least 300–500 contracts at your target strike. Below this threshold, the bid-ask spread is likely to be wide enough to meaningfully reduce your effective premium.
Open interest relative to your trade size: If you are selling 5 contracts, you want OI well above 500. If you are selling 50 contracts, you need OI in the thousands. Your order should not represent a significant portion of the total open interest — if it does, you will move the market against yourself.
Rising OI at your target strike: If open interest has been building at your intended strike over several days, it means other traders are actively positioning there. This usually means better liquidity and tighter spreads when you go to execute.
At Gainsumo, when evaluating covered call opportunities on positions like KULR, FRMI, and RDW, open interest at the target strike is one of the first filters applied — before looking at the premium itself. A generous premium on a contract with 20 open interest is not a good trade.
Open Interest at Key Strike Levels — What It Signals
Large concentrations of open interest at specific strikes are meaningful beyond just liquidity. They can reveal where market participants collectively expect price action to be significant.
Call walls: When a large amount of call open interest exists at a specific strike above the current price, it can act as informal resistance. Market makers who sold those calls are typically hedging by selling shares as the stock approaches that level, which can slow or cap upward price movement.
Put walls: Large put open interest below the current price can act as informal support. Market makers who sold those puts hedge by buying shares as the stock falls toward that level, which can cushion downside.
This dynamic is related to the concept of gamma exposure — the hedging activity of market makers around large OI strikes — and it is why stocks sometimes appear to gravitate toward or get repelled from round-number strike prices.
Max Pain Theory and Open Interest
One concept that uses open interest data is max pain — the strike price at which the maximum number of options contracts expire worthless, resulting in the maximum financial loss for options buyers collectively.
The theory: options sellers (often market makers and institutions) have an incentive for the stock to close at or near the max pain strike at expiration, because that is where they keep the most premium.
Max pain is calculated by finding the strike price where the total dollar value of outstanding calls and puts (weighted by open interest) is minimized for buyers.
Is max pain reliable? It is a useful data point, not a predictive rule. Stocks do not consistently pin to max pain, and many other forces influence price at expiration. But when a stock is trading near the max pain level heading into expiration week, it adds context worth noting — particularly for traders managing positions into expiration.
What Rising and Falling Open Interest Tell You
Rising open interest signals that new positions are entering the market. Traders are committing capital, not closing out. This is neither inherently bullish nor bearish — it simply means conviction is building. Pairing rising OI with the direction of price and whether call or put OI is rising gives you more information.
Falling open interest signals that existing positions are being closed. This can happen because:
- Contracts are expiring worthless
- Traders are taking profits
- Traders are cutting losses
- Positions are being rolled to a different expiration date
Rapidly falling OI after a significant price move often means the move has run its course — the traders who drove it are exiting.
Open Interest and Market Sentiment
Large, unusual concentrations of open interest at specific strikes are sometimes used as a sentiment indicator — particularly in the context of unusual options activity scanning.
Example:
- Stock currently trading at $95
- Massive call open interest suddenly building at the $110 strike, 30 days out
- Volume at that strike is 10x normal
This pattern — especially if the call buying is being done by a single large player — can indicate that someone with significant capital is positioning for a move above $110 before expiration. Whether that is informed speculation or a hedge against an existing position is unknowable from the data alone. But it warrants attention.
This is the foundation of unusual options activity analysis, which we cover separately in our guide to spotting unusual options activity.
Common Beginner Mistakes With Open Interest
Treating open interest as a directional signal
Open interest tells you how many contracts exist — not whether the dominant position is long or short. A call with 10,000 open interest could be 10,000 traders long, 10,000 traders short (writing covered calls), or any combination. Direction requires additional context.
Confusing high volume with high open interest
A contract can have massive volume in a single day from day traders opening and closing positions, while open interest barely moves. Volume is activity; open interest is commitment.
Trading low open interest contracts because the premium looks attractive
A wide bid-ask spread on a low-OI contract will cost you more in execution slippage than almost any premium advantage. Always check OI before executing.
Ignoring open interest when rolling positions
When rolling a covered call to a new strike or expiration, check that the target has adequate OI. Some strikes — especially on smaller stocks — have very limited liquidity past the nearest monthly expiration.
Frequently Asked Questions
What is a good level of open interest for options trading?
There is no universal threshold, but most experienced traders look for at least 300–500 contracts of open interest at their target strike as a minimum. For active day traders or larger position sizes, 1,000+ is preferable. The most actively traded strikes on major stocks like Apple or Nvidia will have open interest in the tens of thousands.
Does open interest update in real time?
No — open interest is typically updated once per day, after the previous trading session closes. Volume updates in real time throughout the trading day. This means the OI figure you see during market hours reflects the prior day’s closing count, not current activity.
Can open interest predict stock price movement?
Not directly. Open interest shows positioning but not direction. Used alongside price action and volume, it can provide context about conviction and liquidity — but it is not a standalone predictive tool.
What happens to open interest when an option is exercised?
It decreases. An exercised option is closed — the contract no longer exists as an open position. The holder has taken delivery of (or sold) the underlying shares instead.
Is high open interest always good?
For liquidity purposes, yes — higher OI generally means tighter spreads and easier execution. But extremely high OI concentrated at a single strike can also indicate a crowded trade with potential for rapid unwinding if the position moves against participants.
How is open interest different from total market volume?
Total market volume aggregates all contracts traded across all strikes and expirations in a single day. Open interest is the cumulative sum of all unclosed contracts across all strikes and expirations at any given moment. They measure related but distinctly different things.
Final Thoughts
Open interest is one of the clearest, most actionable pieces of data on any options chain — and most beginners walk right past it looking only at premium and strike price.
Used correctly, it helps you avoid illiquid contracts with punishing spreads, identify where market participants are building meaningful positions, and select covered call strikes with enough participation to execute efficiently.
The most important habit to develop: before placing any options trade, check the open interest at your target strike alongside the bid-ask spread. If OI is thin and the spread is wide, move to the next strike or the next expiration until you find a contract with adequate market participation.
For a complete picture of the options chain and all the data points that matter alongside open interest, see our guide: What Is an Options Chain? A Simple Beginner Guide.
Ready to put this into practice? Webull gives you free access to real-time options chains with open interest data on every contract. When you are ready to trade covered calls for income, Tastytrade surfaces liquidity metrics and probability data directly in the chain — making OI-based filtering fast and intuitive.
Gainsumo is a content and education platform. This article is for informational purposes only and does not constitute financial advice. Options trading involves substantial risk of loss.
