Checking a Chain Is Worth Trading
Four numbers, four thresholds, and what ignoring them costs over a year of round trips.
Worth reading first: What a Wide Spread Really Costs You
Course catalogue99 lessons
Liquidity is the difference between a strategy you can manage and one you are stuck in. A wide chain does not stop you opening a position. It stops you closing, rolling, or adjusting it without giving back most of what you collected.
Four numbers tell you almost everything, and all four are visible on the chain before you trade.
What a wide spread actually costs
Move the spread width and watch where a realistic fill lands relative to the mid. The gap is a cost you pay on the way in and again on the way out.
Bid $1.95 · Ask $2.05
Filling at the mid means meeting in the middle. You give up half the spread each way. It is not guaranteed, but on a liquid chain it usually fills.
The four numbers
1. Spread width, as a percentage of the mid
The absolute width tells you little. A $0.05 spread on a $0.20 option is enormous; the same width on a $6.00 option is negligible.
Relative spread = (ask − bid) ÷ midThe number that actually matters.
Under 5% is comfortable. Between 5% and 10% is workable if you intend to hold to expiration. Above 10%, closing early costs a meaningful share of the credit, and above 20% the position is effectively one-way.
2. Open interest at the strike
Open interest counts contracts currently outstanding at that strike and expiration. It is the best single proxy for whether anyone else is trading where you want to trade.
A few hundred is fine for a single contract. Under about 100 you are likely to be the only participant, and the quoted spread is a market maker's opening offer rather than a reflection of real two-sided interest.
3. Volume today
Open interest is a stock; volume is a flow. High open interest with zero volume for days means positions were established once and nobody is trading them now.
Volume is also the more honest number around expiration, when open interest lingers on strikes nobody is touching.
4. Whether the whole chain is coherent
Scan the strikes either side of yours. On a liquid chain, prices step down smoothly and spreads stay similar. On an illiquid one you see gaps, strikes with no bid at all, and premiums that do not decline as you move further out of the money.
An incoherent chain means the quotes are not being maintained, which means the price you see is not necessarily a price you can get.
| Metric | Comfortable | Avoid |
|---|---|---|
| Spread ÷ mid | Under 5% | Over 10% |
| Open interest at strike | 500+ | Under 100 |
| Volume today | Some, most days | Zero for days |
| Chain shape | Smooth, two-sided | Gaps, missing bids |
Thresholds worth applying before you look at the premium.
Where liquidity tends to live
Monthly expirations beat weeklies on the same underlying, especially the third-Friday cycle where institutional flow concentrates.
Round strikes beat odd ones. The $50 strike will nearly always be tighter than $52.50.
Near the money beats far out. Deep out-of-the-money strikes on a second-tier name are frequently untradeable in size.
Broad ETFs beat single names, consistently and by a wide margin, one of several reasons they suit the wheel.
Trading a marginal chain
Sometimes you want a position on a chain that is acceptable rather than good. Two habits help.
Always use limit orders, priced at the mid. A market order on a wide chain fills at the far side, and the far side is where the loss is. Start at the mid and walk the price in small steps if it does not fill.
Plan to hold to expiration. If you cannot afford to cross the spread twice, build the position expecting to let it expire, which means the strike has to be one you are comfortable seeing through, since early management is not really available to you.
What can go wrong
Judging the spread in absolute cents. $0.05 is huge on a $0.20 option.
Trusting open interest alone. It can be stale; volume shows current activity.
Using market orders. On a wide chain that is a donation.
Checking liquidity after choosing the strike. It should be a filter on the underlying, applied before you look at premium at all.
Key takeaways
- Judge the spread relative to the mid, not in absolute cents, under 5% is comfortable, over 10% is not.
- Open interest shows accumulated interest; volume shows whether anyone is trading it today. Check both.
- Scan the surrounding strikes: gaps and missing bids mean the quotes are not being maintained.
- You cross the spread twice per round trip, so weekly cycles multiply friction by roughly 100 a year.
- Liquidity is a filter on the underlying, applied before you look at premium at all.
Check your understanding
1. An option is bid $0.20, ask $0.25. Is that spread wide?
2. A strike shows 4,000 open interest but zero volume for a week. What does that suggest?
3. Why does spread width matter more for weekly sellers than monthly sellers?
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