> For the complete documentation index, see [llms.txt](https://docs.koinju.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.koinju.io/data/option-smile.md).

# Option smile

IV-by-strike for a single expiration on the latest snapshot. Both option types returned, ordered by strike. Designed for direct plotting (`x = strike, y = mark_iv`) with optional bid/ask brackets.

The endpoint is a focused projection of [Option chain](/data/option-chain.md) — same underlying data, narrower column set, server-side filtered to non-zero IV.

## SQL API

The smile shape comes from the same `api.option_chains` table:

```sql
WITH (
  SELECT max(timestamp)
  FROM api.option_chains
  WHERE exchange = 'deribit' AND underlying_asset = 'BTC'
) AS latest_ts
SELECT strike, option_type, mark_iv, bid_iv, ask_iv, delta, underlying_price
FROM api.option_chains
WHERE exchange = 'deribit'
  AND underlying_asset = 'BTC'
  AND toDate(expiration) = toDate('2026-06-26')
  AND timestamp = latest_ts
  AND mark_iv != 0
ORDER BY strike, option_type
```

Plot the result as a scatter / line over `(strike, mark_iv)` to see the smile. For an OTM-only wing curve, filter to `option_type = 'C' AND strike > underlying_price` (calls above spot) and `option_type = 'P' AND strike < underlying_price` (puts below spot).

### Cross-expiration vol surface

To build a vol surface, query each expiration in turn (or join with `dte` in the result):

```sql
WITH (
  SELECT max(timestamp)
  FROM api.option_chains
  WHERE exchange = 'deribit' AND underlying_asset = 'BTC'
) AS latest_ts
SELECT
  toDate(expiration)                                AS expiry,
  strike / toFloat64(underlying_price)              AS moneyness,
  mark_iv                                           AS iv,
  toUInt32(date_diff('day', timestamp, expiration)) AS dte
FROM api.option_chains
WHERE exchange = 'deribit'
  AND underlying_asset = 'BTC'
  AND mark_iv != 0
  AND timestamp = latest_ts
ORDER BY expiry, moneyness
```

## REST API

## Get Volatility Smile

> IV-by-strike for a single expiration on the latest snapshot. Both option types (C/P) returned, ordered by strike. Designed for direct plotting (x=strike, y=mark\_iv).<br>

```json
{"openapi":"3.1.1","info":{"title":"Koinju Market Data API","version":"1.0.0"},"servers":[{"url":"https://api.koinju.io","description":"Koinju API Server"}],"security":[{"apiKeyAuth":[]}],"components":{"securitySchemes":{"apiKeyAuth":{"type":"apiKey","in":"header","name":"x-api-key","description":"Required for /ohlcv and /trade endpoints.\nPass your API key in the x-api-key header.\nPublic /market/* endpoints do not require authentication.\n"}},"schemas":{"OptionSmileRow":{"type":"object","properties":{"strike":{"type":"number","format":"decimal","description":"Strike price"},"option_type":{"type":"string","enum":["C","P"],"description":"Call or Put"},"mark_iv":{"type":"number","format":"decimal","description":"Mark implied volatility (annualized %)"},"bid_iv":{"type":"number","format":"decimal","description":"Bid IV"},"ask_iv":{"type":"number","format":"decimal","description":"Ask IV"},"delta":{"type":"number","format":"decimal","description":"Delta"},"underlying_price":{"type":"number","format":"decimal","description":"Spot/index price of the underlying at snapshot time"},"dte":{"type":"integer","description":"Days-to-expiry"}}}}},"paths":{"/option/smile":{"get":{"summary":"Get Volatility Smile","description":"IV-by-strike for a single expiration on the latest snapshot. Both option types (C/P) returned, ordered by strike. Designed for direct plotting (x=strike, y=mark_iv).\n","tags":["market_data"],"parameters":[{"name":"exchange","in":"query","required":true,"schema":{"type":"string","enum":["deribit","binance","okx","bybit"]},"description":"Exchange — one of `deribit`, `binance`, `okx`, `bybit`."},{"name":"underlying_asset","in":"query","required":true,"schema":{"type":"string"},"description":"Underlying coin (e.g. `BTC`)."},{"name":"expiration","in":"query","required":true,"schema":{"type":"string","format":"date"},"description":"Expiry date, ISO (`YYYY-MM-DD`). Required."}],"responses":{"200":{"description":"OK","content":{"application/json":{"schema":{"type":"array","items":{"$ref":"#/components/schemas/OptionSmileRow"}}}}}}}}}}
```