The Option Chain Columns Most Traders Skip Past
Strike, bid, and ask are only the starting five
A basic pass at an option chain stops at five columns: strike, bid, ask, volume, and open interest. That's enough to place a simple order, but most platforms — including OptionScope — let you toggle on a wider set: delta, gamma, theta, vega, mark price, implied volatility, and the day's change. These aren't decoration. Each one answers a question the basic five can't, and scanning them together turns the chain from a price list into an actual read on the market's positioning.
The Greeks columns, row by row
When a chain shows Greeks per contract, each column is really a snapshot of sensitivity for that specific strike and expiration. The delta column tells you how many cents the option moves per one-dollar move in the stock, and it also roughly tracks how far in or out of the money a strike sits — delta drifts toward 1.0 (or -1.0 for puts) deep in the money and toward 0 far out. The gamma column peaks at the strike closest to the current stock price and falls off on either side, which is why at-the-money contracts feel the most reactive to every tick. Theta gets more negative as you move to nearer-dated expirations at the same strike, showing which rows are bleeding value fastest per day. Vega runs the other direction — it's largest in the longest-dated expirations, because more time outstanding means more room for volatility to swing the outcome. A quick pass down these four columns for a single expiration tells you more about the risk profile of each strike than the price columns alone ever could. For the full mechanics behind each Greek, see the Greeks beyond delta.
Mark vs. last vs. mid — which price is real
Chains often show three different numbers that all claim to be "the price," and they answer different questions. Last is the price of the most recent trade — on a thin contract that trade might be minutes or hours old and no longer reflect the current market. Mid is simply the midpoint between the current bid and ask, recalculated continuously. Mark is a reference price computed by the exchange or broker, frequently close to the midpoint but sometimes adjusted by a formula that accounts for a wide or one-sided market; it's the number most brokers use for margin calculations and account valuation. On a liquid, tight-spread contract the three converge and it barely matters which you read. On a thin contract with a wide bid-ask, last can be stale and misleading — mid or mark is the more honest read of what the option is actually worth right now. More on why that gap widens on illiquid strikes in the hidden cost of a wide bid-ask spread.
The IV column is a compressed skew chart
If a chain shows implied volatility per strike for a single expiration, you can see volatility skew without ever opening a separate chart. Scan down the put side from at-the-money toward far out-of-the-money strikes and the IV numbers typically climb — the market is pricing more expected movement into downside protection than the pure math of distance-from-spot would suggest. Scan the call side and the climb is usually gentler, sometimes closer to flat. That asymmetry in the raw numbers is the same skew that shows up as a smirk-shaped curve on a volatility surface plot; the chain just presents it as a column of numbers instead of a line. The full explanation of why puts skew richer is in why OTM puts almost always cost more than OTM calls.
Change and %change: a coarse proxy for order flow
The change and percent-change columns show how much a contract's price moved from the prior close, but on their own they don't tell you whether that move was driven by buying or selling pressure — a big percentage gain on a put could mean urgent bearish demand, or it could just mean the stock gapped down and the put's intrinsic value caught up mechanically. The column becomes far more useful paired with volume relative to open interest: a large price change on a strike where today's volume also exceeds existing open interest is a much stronger signal of fresh, deliberate positioning than the same price change on a strike trading its usual light volume. That comparison is worth doing systematically — see open interest vs. volume for how the two combine.
None of these columns need to be memorized in isolation — the point is reading two or three together for the same row. A strike with rising IV, a widening bid-ask, and volume well above open interest is telling a very different story than a strike with flat IV and volume in line with its usual average, even if their prices moved by the same dollar amount. Scan the full column set yourself in the option chain.