Put/Call OI Ratio

Q: What does P/C ratio tell you?

Reveals balance between hedging and speculation. Above 1.0 = more puts (institutional hedging). Below = more calls (retail speculation).

Q: How does it relate to max pain?

Put-heavy chains have max pain above spot (puts expire worthless if price stays up). Call-heavy chains have max pain below spot.

Q: Why does Put/Call OI Ratio matter for trading?

The put/call OI ratio is a long-established sentiment gauge. At historical extremes, it flags crowd positioning that's usually wrong — setting up contrarian trades. Traders use it alongside breadth, VIX, and survey-based sentiment to time entries against the crowd.

Q: When is Put/Call OI Ratio good versus bad for a trader?

Very high ratios are good for contrarian longs (capitulation setup). Very low ratios are good for contrarian shorts or hedge-buying (euphoria setup). Mid-range readings carry no signal — rely on other inputs. Single-stock readings are noisier than index readings; stick to SPX / SPY / QQQ for signals.

Canonical definition, formula, interpretation, and API reference.

Definition

Total put OI / total call OI. Measures whether positioning is hedging-dominated (>1) or speculation-dominated (<1).

Formula

P/C OI Ratio = Sum(put OI) / Sum(call OI)

Simple ratio across all strikes and expirations.

Inputs

total put OItotal call OI

Output

put_call_oi_ratio

Interpretation

>1.0: put-heavy, institutional hedging dominates
<1.0: call-heavy, speculative buying
Near 1.0: balanced chain, max pain near ATM

API Reference

Endpoint

GET /v1/maxpain/{symbol}

Tier

Basic+

Response field

put_call_oi_ratio

Why Put/Call OI Ratio Matters for Trading

TL;DR

The put/call OI ratio is a sentiment extreme detector. Extreme highs = capitulation (bounce setups). Extreme lows = euphoria (correction risk).

What it measures: Ratio of total put open interest to total call open interest across the chain.
What it signals: Aggregate positioning bias. Contrarian at extremes; noise in the middle.
Why we measure it: Crowds are wrong at the margin. The ratio surfaces those margins.
Who uses it: Contrarian traders, swing traders, sentiment-model users, retail.

How to read Put/Call OI Ratio

Very high (>1.3)

Put-heavy positioning = fear
Often marks local bottoms
Contrarian long setup
Historical mean-reversion edge

Good for: contrarian longs

Very low (<0.6)

Call-heavy = euphoria
Often marks local tops
Contrarian short setup
Post-rally exhaustion signal

Good for: contrarian shorts / hedge buys

Typical range (0.7–1.0)

Normal sentiment
No signal
Trade on other factors
Background reading

Neutral

Rules of thumb

Use absolute extremes, not rolling highs. A 'high' ratio in a bull market may be mid-range historically. Compare to a multi-year distribution.
Distinguish OI vs volume ratio. OI ratio is slow/structural. Volume ratio is fast/tactical. Both useful, different use cases.
Fades fastest at SPX index level. SPX put/call is the most reliable signal; single stocks noisy.
Pair with fear & greed. Ratio extremes + sentiment extremes = higher-conviction contrarian setups.
Signal is late, not perfect. Extremes can persist. Contrarian entries need confirmation (price reversal, vol pattern).