How is an options chain laid out?
Most platforms build the chain the same way, as in the drawing at the top of this page:
- Expirations run across the top as tabs or a list, often with the days left. Each expiration is its own chain.
- Strikes run down the middle column, from low to high.
- Calls sit on the left and puts on the right, each with its own columns. Some apps show only calls or only puts and switch with a toggle.
- A line or a highlighted row marks the stock price, here $102.40, between the 100 and 105 strikes.
- In-the-money contracts are shaded: calls with strikes below the price, puts with strikes above it.
- Options chain
- The list of all calls and puts on one underlying for one expiration, with one row per strike and columns for prices, activity and Greeks.
- In the money (ITM)
- A call whose strike is below the stock price, or a put whose strike is above it. Chains usually shade these contracts.
What do bid, ask, mark and last mean?
Prices are quoted per share, and a standard US stock option covers 100 shares, so multiply by 100 for the cost of one contract. The bid is the highest price a buyer is offering now, roughly what you would get if you sold at market. The ask is the lowest price a seller will accept, what you would pay if you bought at market. The mark is usually the midpoint, (bid + ask) ÷ 2, and platforms use it to value open positions.
Last is the price of the most recent trade and change is that price against the previous close. On a quiet contract the last trade can be hours old, so trust the live bid and ask more. In the drawing, the $105 call is quoted 2.41 bid and 2.51 ask: the mark is 2.46, and buying one contract at the ask costs $251.
- Mark (mid price)
- The midpoint between the bid and the ask, (bid + ask) ÷ 2. Platforms use it to value positions; it is a reference price, not a guaranteed fill.
What do volume, open interest and implied volatility tell you?
Volume counts the contracts traded so far today. Open interest counts the contracts still open from earlier sessions; the Options Industry Council explains that the OCC calculates it from the day’s opening and closing trades, and platforms update it once a day, not during the session. Together they tell you whether a strike has an active market. The open interest lesson covers how to read them.
Implied volatility (IV) is the size of move the option’s price implies, as an annualized percentage. It differs by strike: in the drawing, IV runs from 34.0% at the 95 strike to 29.5% at 110, a typical volatility skew. Higher IV means a more expensive option for the same strike and time; the implied volatility lesson explains IV rank and IV crush.
How do you read delta and the other Greeks in the chain?
Many chains show delta by default and let you add gamma, theta and vega. FINRA defines delta as the amount an option’s price is expected to change for a $1 change in the stock, theta as the change in its value for each day that passes, and vega as the change for a one-point move in implied volatility. Gamma is how fast delta itself changes.
For the hypothetical $105 call, a standard model with the chain’s inputs gives a delta of 0.40, about +$40 per contract for a $1 rise in XYZ; a theta of −0.058, about −$5.78 per contract per day if nothing else changes; and a vega of 0.114, about $11.37 per contract for each point of IV. Put deltas are negative: the $100 put shows −0.38. The options Greeks lesson explains each one in depth.
How to judge liquidity from the chain
A good strike on a thin market can still be a bad trade, because you pay the spread on the way in and again on the way out. Measure the spread against the price, not in cents: spread ÷ mark. Then check volume and open interest.
In the same chain, the $105 call is quoted 2.41 × 2.51: a 0.10 spread on a 2.46 mark, 4.1%, with 1,240 contracts traded today and 5,600 open. The $115 call is quoted 0.30 × 0.46: a 0.16 spread on a 0.38 mark, 42.1%, with 9 traded and 140 open. Buy at the ask and sell straight back at the bid, and the first costs $10 per contract, the second $16, which is 42% of what the option is worth. Use limit orders near the mark, and skip strikes whose spread is large next to your planned profit; the bid-ask spread lesson has more.
How do you find the breakeven of a long call or put?
At expiration, a long call breaks even at the strike plus the price you paid, and a long put at the strike minus the price you paid. Use the price you would actually pay, usually the ask or near it, not the mark.
The $105 call bought at the 2.51 ask breaks even at $107.51, 4.99% above the current $102.40, and the most it can lose is the $251 paid. The $100 put bought at its 2.68 ask breaks even at $97.32, 4.96% below the price. Those percentages are the moves the stock must make by expiration just to get your money back; before expiration the option also carries time value, which is why how to choose a strike price starts from your target on the chart. The call vs put lesson works through both formulas.
Worked example: reading one row of the XYZ chain (hypothetical)
Hypothetical: XYZ trades at $102.40 and your chart plan expects a move toward $108 within a few weeks. Here is the $105 call row of the 30-day chain, read from left to right:
- Expiration: 30 days, chosen from the tabs. Moneyness: out of the money, since 105 is above 102.40, so the row is not shaded.
- Quote: 2.41 × 2.51, mark 2.46. One contract costs $251 at the ask.
- Liquidity: spread 0.10, or 4.1% of the mark; volume 1,240; open interest 5,600. Tradable with a limit order.
- Implied volatility: 30.5%, between the 32.0% of the 100 strike and the 29.5% of the 110 strike.
- Greeks: delta 0.40 (about +$40 per $1 in XYZ), theta about −$5.78 a day, vega about $11.37 per IV point.
- Breakeven at expiration: $107.51, a 4.99% rise. Your $108 target clears it, but only by 49 cents, so the trade needs the move to come soon; if the plan’s stop on XYZ is hit, the option is sold, not held to expiration.