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Crypto options glossary

What is open interest in options?

Open interest (OI) is the number of option contracts that are open and not yet closed or expired. It shows where traders have money at stake. On Bitcoin, strikes with heavy call OI above the price and heavy put OI below it are watched as resistance and support, often called OI walls.

  • OI counts open contracts, not trades.
  • Volume is what traded today; OI is what is still open.
  • Heavy call OI above the price is a call wall; heavy put OI below, a put wall.
  • Each expiry has its own OI, and it clears when that expiry settles.
OI profileDelta · 9:39 am IST
Puts · supportStrikeCalls · resistance
85,200
85,000
84,800
84,600
84,400
84,200
84,000
83,800
83,600
83,400
83,200
83,000
82,800
82,600
Now 83,931
  • If the wall holdsSell the 85,800 call. Paid while price stays under it.
  • If both walls holdSell 83,800 and 85,800. Paid while price stays between.
  • If price is rejected at the wallA bear spread from 85,800 back down.
  • If price breaks throughA bull spread above 85,800, risk capped.

Today · 0DTE · settles 5:30 pm

Questions people ask

Is high open interest bullish or bearish?

Neither on its own. What matters is where it sits: heavy call OI above the price can act as a ceiling, heavy put OI below as a floor. Rising OI with a rising price shows new money following the move.

What is the difference between open interest and volume?

Volume counts every contract traded today, opened or closed. Open interest counts the contracts still open. A day can have huge volume and little change in OI if traders only swapped positions.

Why do OI walls matter on expiry day?

Sellers of those strikes want the price to stay away from them, and hedging around big positions can slow the price as it approaches. It is a tendency traders watch, not a rule, and big news overrides it.

What is an OI wall?

A strike with unusually heavy open interest close to the price. A call wall sits above the price and is read as resistance; a put wall sits below and is read as support, because the sellers of those options lose if the price crosses them.

Can open interest fall on a high-volume day?

Yes. Volume counts every trade, including trades that close positions. If more contracts were closed than opened, open interest falls however busy the day was.

What happens to open interest at expiry?

It goes to zero for that expiry. The contracts are settled and cease to exist, and the next expiry's open interest starts from its own level. That is why the walls are redrawn after every settlement.

Keep going

How open interest changes, worked through

Open interest rises only when a new contract is created, and falls only when one is closed. An example in three trades shows the difference.

First: Asha buys 10 new calls and Bilal sells 10 new calls. Ten contracts now exist that did not before, so open interest rises by 10. Second: Asha sells her 10 calls to Chitra, who is opening a position. The contracts just changed hands, so open interest is unchanged, though volume counted another 10. Third: Chitra and Bilal both close. The 10 contracts are gone, and open interest falls by 10.

That is why a day can have heavy volume and flat open interest: traders were swapping positions, not adding to them.

Price and open interest together

A common way to read the two side by side. It is a convention among traders, not a law.

PriceOpen interestCommon reading
RisingRisingNew money is following the move
RisingFallingShorts are closing; the move may be tiring
FallingRisingNew shorts or new hedges are being added
FallingFallingLongs are giving up their positions

How Algoclear finds the walls

A wall is not simply the biggest bar on the chart. On a weekly expiry the largest open interest often sits at strikes very far from the price, bought as cheap lottery tickets or crash insurance, and nobody expects Bitcoin to reach them this week.

Algoclear marks the nearest strike beyond the price whose open interest is at least one and a half times the average, looking within about two expected moves of the price for a weekly expiry. The same rule is used on Market now, on the chart's OI profile and in the ready strategies built from the walls, so the three always agree.

Reading an OI profile

An OI profile draws call and put open interest at each strike, with the price marked. Heavy call OI above the price and heavy put OI below it outline the range option sellers are betting on. Algoclear's OI profile draws this for Bitcoin, Ethereum and Gold.

Using OI to place trades

Many range traders sell strikes at or beyond the walls, so the price has to break through heavy positioning before they lose. Breakout traders watch the same walls the other way: a clean break through one can move fast as those sellers cover.

Common mistakes with open interest

Open interest says where positions are, not which way they point.

  • Reading it as direction. Every open contract has a buyer and a seller, so high call open interest is not a bullish vote.
  • Trusting a wall through big news. Walls matter most on quiet days close to expiry.
  • Mixing expiries. Each expiry has its own open interest, and it disappears when that expiry settles.
  • Treating a far-away giant strike as resistance. It is usually insurance or a lottery ticket.
  • Reading walls without max pain and the put-call ratio. The three describe the same positions from different sides.

Written by the Algoclear team · Updated 22 September 2026 · Examples use Bitcoin options on Delta Exchange India.

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Options trading carries risk, and you can lose money. Algoclear is a trading tool, not investment advice.