Highest OI Strike
Canonical definition, formula, interpretation, and API reference.
Definition
Strike with most total open interest (calls + puts). Not the same as call/put wall which use gamma weighting.
Formula
argmax(call_OI + put_OI) across all strikes
Simple maximum of total OI per strike.
Inputs
open interest per strike
Output
highest_oi_strike (price)
Interpretation
- Often at round numbers
- High OI = significant hedging potential
- Different from gamma-weighted walls
Live Example: SPY
Live SPY OI data temporarily unavailable. See /stock/spy/gamma for current values.
API Reference
Endpoint
GET /v1/exposure/levels/{symbol}
Tier
Free
Response field
levels.highest_oi_strike
Why Highest OI Strike Matters for Trading
TL;DR
The highest-OI strike is the single largest open-interest pile on the chain — often the max pain candidate, always a level to watch into expiry.
- What it measures
- The strike with the largest combined (call + put) open interest on the full chain, or for a specific expiry.
- What it signals
- Where the most contracts will settle at expiry — where dealer pin forces are largest.
- Why we measure it
- OI is a positioning snapshot. Concentrated OI creates asymmetric outcomes at expiration because it crystallises dealer hedging into a single level.
- Who uses it
- Expiry traders, OPEX scalpers, pin-play specialists, and systematic flow analysts.
How to read Highest OI Strike
High OI near spot into expiry
- Pin forces support the level
- Price pulls toward strike late in session
- Strong OPEX effect
- Often converges with max pain
Good for: short strangles centered at strike
High OI far from spot
- Pin absent — level too far
- OI meaningful only if spot approaches
- Not actionable until proximity
- Treat as reference only
Out of range
No clear highest OI
- OI diffused across strikes
- No pin candidate
- Fall back to top strikes
- Typical for illiquid names
Diffuse
Rules of thumb
- Only matters near expiry. Highest-OI outside of OPEX week is just a positioning reference, not an actionable level.
- Close distance matters. OI 5% away on expiry day won't pin. OI 0.5% away will.
- Pair with pin risk. Pin risk score quantifies the probability — highest-OI strike identifies the level.
- Check call vs put balance. Skewed OI (all puts or all calls at one strike) behaves differently than balanced OI.
- Ignore in active negative-gamma. Pin requires dampening behaviour. In negative gamma, price blows through the level.
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