The option chain shows open interest (OI) at one moment. The strike OI tracker shows how it got there: call and put OI at up to three strikes, minute by minute, from our recordings of the option chain.
What the lines mean
- Call OI rising at a strike above the price: traders are selling calls there and expect the index to stay below it, so it acts as resistance.
- Put OI rising at a strike below the price: traders are selling puts and expect the index to stay above it, so it acts as support.
- OI falling: positions are being closed. Call OI falling as the price rises towards the strike often means call sellers are giving up (short covering), and resistance is weakening.
Using it
The page opens on the at-the-money strike and the strikes with the most call and put open interest. Watch whether the big strikes keep adding OI or start to unwind as the price comes near them. Hover or tap a chart for the exact OI and option prices at any minute, and pick another day to compare.