> ## Documentation Index
> Fetch the complete documentation index at: https://docs.backquant.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Glossary

> Quick-reference for every term used across the docs

Alphabetical. If you're new to options analytics, start with
[What is GEX?](/concepts/gex) and the [IV suite](/concepts/iv-suite)
overviews instead — those build the mental model. Use this page as a
lookup once concepts land.

## A

**Anchor expiry** — A monthly or quarterly options expiration. Heavier
OI than weeklies; institutional positioning concentrates here. See
[OPEX calendar](/concepts/opex).

**ATM IV** — At-the-money implied volatility. The IV of options whose
strike equals current spot. Used as the "headline" vol for an expiry.

## B

**Backwardation (vol)** — Term structure where front-month IV is
higher than back-month IV. Common during stress. See
[IV suite](/concepts/iv-suite).

**Breeden-Litzenberger** — The technique that extracts a probability
distribution from option prices. The basis of
[`/v2/options/probability/density`](/api/v2/options/probability/density).

**Butterfly** — `(25Δ put IV + 25Δ call IV) / 2 − ATM IV`. Measures
the curvature of the smile / how richly priced the wings are.

## C

**Call resistance** — The strike with the largest positive net gamma
above spot. Often a reversal level — dealers sell into rallies toward
this strike. See [What is GEX?](/concepts/gex).

**Call wall** — Synonym for call resistance. `call_wall_2` and
`call_wall_3` are the second and third strongest above spot.

**Cardle (candle)** — OHLCV bar. The terminal renders 30m candles by
default; the API ships them alongside GEX levels when
`?include=candles` is set.

**Charm** — `∂Delta/∂Time`. Drives end-of-day and pre-OPEX delta
hedging flows. See [Greeks beyond delta](/concepts/greeks).

**`computed_at`** — ISO timestamp in `meta` showing when the underlying
cache was last written by our worker. Pair with `freshness_seconds`.

**Confidence band** — A price range containing X% of implied
probability mass for an expiry. Returned by
[`/v2/options/probability/density?confidence_band=0.68|0.95`](/api/v2/options/probability/density).

**Contango (vol)** — Term structure where back-month IV is higher than
front-month IV. The "normal" regime in low-vol periods.

## D

**DEX** — Dollar delta exposure. Net delta dealers carry per strike,
in USD terms. See [Greeks beyond delta](/concepts/greeks).

**DTE** — Days to expiration. An integer count.

## E

**Expected move** — The 1σ implied price range for the next 24 hours,
derived from ATM straddle pricing. Returned by
[`/v2/options/expected-move`](/api/v2/options/expected-move) or as part
of `/v2/gex/levels?include=expected_move`.

**Expiry token** — Deribit-style date encoding, e.g. `28MAR25` =
March 28 2025. Every endpoint that returns one also returns
`expiry_date` (ISO) when parseable.

## F

**`freshness_seconds`** — `now − computed_at`. Useful for staleness
alarms. See [Data freshness](/concepts/data-freshness).

## G

**Gamma** — Rate of change of delta with respect to spot. The greek
that drives dealer hedging behaviour around walls.

**Gamma flip** — The strike where cumulative net dealer gamma crosses
zero, closest to spot. Above the flip, dealers stabilise; below, they
amplify. Reported as `hvl` in the levels response.

**GEX** — Gamma exposure. The flagship analytic. See
[What is GEX?](/concepts/gex).

## H

**HVL** — Hedging Volume Level. Same as the gamma flip — the regime
line for dealer behaviour.

**HYPEUSDT** — Hyperliquid's HYPE token. One of the four supported
symbols (`BTCUSDT`, `ETHUSDT`, `SOLUSDT`, `HYPEUSDT`).

## I

**IV** — Implied volatility. The volatility level the market is pricing
into options.

**IV rank** — Where current IV sits between its 52-week low and
high. Not currently exposed in v2 (planned).

**IV-RV spread** — `IV − RV`. Positive = options expensive vs realised
move; negative = cheap. Returned by
[`/v2/options/iv/iv-rv`](/api/v2/options/iv/iv-rv).

## M

**Max pain** — The strike where option *writers* profit most at expiry.
See [Max pain](/concepts/max-pain).

**Moneyness** — `strike / spot`. `0.9` = 10% OTM (for calls) /
10% ITM (for puts). Used as a strike filter on most endpoints
(`?moneyness_min=0.9&moneyness_max=1.1`).

## N

**Net GEX** — Sum of call GEX and put GEX at a strike (or aggregated
across the chain). Positive net = stabilising; negative = amplifying.

**Notional OI (USD)** — `total_oi × spot_price`. The dollar size of
the position behind the OI count. Surfaced on every OPEX expiration.

## O

**0DTE** — Zero days to expiration. Options expiring today. Many
endpoints have a 0DTE variant of their levels (`odte_hvl`,
`odte_call_resistance`, etc.).

**OI** — Open interest. The number of contracts outstanding.

**OPEX** — Options expiration. See
[OPEX calendar](/concepts/opex).

## P

**PCR** — Put / call ratio. OI-weighted ratio of put OI to call OI.
PCR > 1 = defensive; PCR \< 1 = call-heavy. See
[`/v2/options/pcr`](/api/v2/options/pcr).

**PDF (probability density function)** — The implied probability
distribution of the underlying at a future expiry. See
[Probability density](/concepts/probability-density).

**Pin risk** — The likelihood of price pinning to a strike on expiry
day. Highest when max pain and gamma walls cluster near spot.

**Premium tide** — Net options premium and notional volume tilt. See
[`/v2/options/premium-tide`](/api/v2/options/premium-tide).

**Put support** — The strike with the largest positive net gamma below
spot. Often a bounce level — dealers buy on dips into this strike.

**Put wall** — Synonym for put support. `put_wall_2` and `put_wall_3`
are the second and third strongest below spot.

## Q

**Quarterly expiry** — Last Friday of March, June, September, or
December. The heaviest OI bucket of the year.

## R

**Risk reversal** — `25Δ call IV − 25Δ put IV`. Positive = call
premium; negative (the more common case) = put premium / fear bid.
Surfaced on [`/v2/options/iv/skew`](/api/v2/options/iv/skew).

**RV** — Realised volatility. The vol that actually happened over a
trailing window (typically 30 days).

## S

**Skew** — The asymmetry between OTM put IV and OTM call IV. Crypto
typically prices puts richer (positive skew). See
[IV suite](/concepts/iv-suite).

**Smile** — The shape of IV when plotted by strike. ATM is the
trough; OTM puts and OTM calls are the wings.

**Source** — `meta.source` lists the upstream venues each response
touched (`["deribit", "bybit", "okx", "binance"]`). Provenance.

**`spot_price`** — Current spot price for the symbol, snapshotted at
the time of computation. Returned in `meta` on every endpoint.

**Stress history** — Long-window record of HVL and walls from the
persistent store. Used for backtests.
[`/v2/gex/stress-history`](/api/v2/gex/stress-history).

## T

**Term structure** — The curve of ATM IV plotted against expiry tenor.
Slope tells you the market's vol forecast across time.
[`/v2/options/iv/term-structure`](/api/v2/options/iv/term-structure).

**Theta** — Time decay. Premium that bleeds out of an option as time
passes. Useful as a rough estimate of dealer income from selling
premium. See [Greeks beyond delta](/concepts/greeks).

## V

**Vanna** — `∂Delta/∂IV`. Drives "vol-rallies-the-tape" hedging
flows. See [Greeks beyond delta](/concepts/greeks).

**Vega** — Sensitivity to IV moves. Where dealer P\&L is concentrated
when vol shifts.

**VRP** — Volatility risk premium. The persistent gap by which
implied vol exceeds realised vol. See
[`/v2/options/vrp`](/api/v2/options/vrp).

## W

**Weekly expiry** — A Friday expiration that is *not* the last Friday
of the month. Lighter OI than monthlies, more responsive to short-term
positioning.