# Premium / volume by expiration for a strike

`GET https://flow-api.skylit.ai/v1/underlying/{ticker}/by-strike/{strike}/expirations`

API: Flowseeker.

For a single strike on the underlying, breaks the requested
window's premium and volume out by expiration date.

## Authentication

Send your Skylit API key as a bearer token: `Authorization: Bearer <key>`. No other header is accepted.

## Parameters

| Name | In | Type | Required | Description |
| --- | --- | --- | --- | --- |
| `ticker` | path | string | yes | Underlying ticker symbol (uppercase, e.g. `SPY`, `AAPL`). |
| `strike` | path | string | yes | Strike price (decimal allowed; e.g. `580` or `580.5`). |
| `interval` | query | string | no |  (one of `1D`, `1W`, `7D`; default `1D`) |
| `dte_filter` | query | string | no |  (one of `all`, `0-7`, `8-30`, `31-90`, `90+`; default `all`) |
| `date` | query | string (date) | no | Trading date the request targets, in `YYYY-MM-DD`. Defaults to the current trading date (the most recent session that has settled enough data to be queryable). |

## Example request

```bash
curl "https://flow-api.skylit.ai/v1/underlying/SPY/by-strike/580/expirations" \
  -H "Authorization: Bearer $SKYLIT_API_KEY"
```

## Responses

### 200

Expiration breakdown for the strike.

Shape (placeholder values):

```json
{
  "data": {
    "ticker": "string",
    "strike": 0,
    "interval": "1D",
    "totalCallPremium": 0,
    "totalPutPremium": 0,
    "topExpiration": "string",
    "expirationCount": 0,
    "bars": [
      {
        "expiration": "string",
        "dte": 0,
        "callVolume": 0,
        "putVolume": 0,
        "callPremium": 0,
        "putPremium": 0
      }
    ]
  },
  "meta": {
    "timestamp": "string",
    "requestId": "d7574836"
  }
}
```

### 400

Request validation failed.

invalidParam:

```json
{
  "error": {
    "code": "BAD_REQUEST",
    "message": "Invalid parameter 'timeframe': must be one of [1m, 5m, 15m, 1h, 4h, 1d, 1w, 1M]"
  }
}
```

### 401

Missing or invalid API key.

missingKey:

```json
{
  "error": {
    "code": "UNAUTHORIZED",
    "message": "Authentication required"
  }
}
```

### 402

The account's shared Skylit credit balance is lower than this route's cost. Top up to continue. Carries `X-Credits-Remaining: 0`.

Headers: `X-Credits-Remaining`.

outOfCredits:

```json
{
  "error": {
    "code": "insufficient_credits",
    "message": "Out of credits. Top up to continue making requests."
  }
}
```

### 429

Per-minute rate limit exceeded.

Headers: `Retry-After`.

tooFast:

```json
{
  "error": {
    "code": "RATE_LIMITED",
    "message": "Rate limit of 100 req/min exceeded. Retry after 18s."
  }
}
```