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

# GET /perps/basis: Mark, Index and Basis

> OHLC of Polymarket Perps mark, index and basis in basis points per bucket, at the interval you pick. Scope analytics.read.

> [!NOTE]
>
> Sign each request with a fresh HMAC signature. The cURL and HTTP header values below are placeholders, not reusable credentials. For runnable signing code, use [request signing examples](https://docs.bravadotrade.com/authentication-examples.md).

OHLC of the **mark price**, the **index price** and the **basis** (in basis points) for one instrument, bucketed at the interval you pick. `premium_recomputed` is `null` with provenance until the order-book layer exists; nothing is fabricated in its place. This endpoint takes the same parameters and the same interval-dependent ranges as [open-interest history](https://docs.bravadotrade.com/api/perps-data/oi-history.md). Part of the [Perps Data](https://docs.bravadotrade.com/products/perps-data.md) product; scope `analytics.read`.

```text theme={null}
GET https://partner-api.bravadotrade.com/perps/basis
```

### Query Parameters

**instrument** `string` *required*

The instrument, by its venue-native id (for example `6`) or its canonical symbol (for example `BTC`). Matches `[A-Za-z0-9._-]{1,32}`.

**interval** `string`

Bucket size: one of `1m`, `5m`, `15m`, `1h`, `4h`, `1d`. The interval sets the maximum window, below.

**venue** `string`

One of `polymarket`, `binance`, `bybit`, `hyperliquid`. Omit for the default. Polymarket is the covered venue.

**from** `string`

Start of the window. Accepts RFC3339, unix seconds or unix milliseconds.

**to** `string`

End of the window. Same formats as `from`. The maximum window depends on `interval` (below); a wider range is refused with `400 range_too_large`.

**limit** `integer` (default: 1000)

Rows per page, `1`–`5000`.

> [!NOTE]
>
> The maximum window is set by `interval`: `1m` → 1 day, `5m` → 7 days, `15m` → 21 days, `1h` → 90 days, `4h` → 180 days, `1d` → 400 days.

### Response

Bars in `data`, one per interval, oldest first. When `has_more` is `true`, page forward by passing `next_from_s` (unix **seconds**) back as `from`.

**instrument** `string`

The instrument the bars are for.

**interval** `string`

The bucket size actually used.

**data** `array`

**Bar fields**

**ts** `integer`

The bar's boundary timestamp.

**mark\_open** `string`

Mark price at the start of the bar. `mark_high`, `mark_low` and `mark_close` complete the mark OHLC.

**idx\_open** `string`

Index price at the start of the bar. `idx_high`, `idx_low` and `idx_close` complete the index OHLC.

**basis\_bps\_open** `string`

Basis in basis points at the start of the bar. `basis_bps_high`, `basis_bps_low` and `basis_bps_close` complete the basis OHLC.

**mark\_minus\_idx\_close** `string`

Mark minus index at the close of the bar, in price units.

**premium\_recomputed** `string | null`

Premium recomputed from the order book. `null` until the order-book layer exists — never a fabricated value.

**ticks** `integer`

How many source observations the bar aggregates.

**has\_more** `boolean`

`true` when more rows remain beyond this page.

**next\_from\_s** `integer`

Present when `has_more` is `true`. Unix **seconds** — pass it back as `from` to read the next page.

### Example

```bash cURL theme={null}
curl -G https://partner-api.bravadotrade.com/perps/basis \
  -H "X-BRAVADO-API-KEY: $BRAVADO_API_KEY" \
  -H "X-BRAVADO-TIMESTAMP: <unix-ms>" \
  -H "X-BRAVADO-SIGNATURE: <signature-for-this-request>" \
  -d instrument=BTC \
  -d interval=1h \
  -d from=2026-10-01T00:00:00Z \
  -d to=2026-10-02T00:00:00Z
```

```json Response (abbreviated) theme={null}
{
  "instrument": "BTC",
  "interval": "1h",
  "data": [
    {
      "ts": 1759276800,
      "mark_open": "90012.00",
      "mark_high": "90280.00",
      "mark_low": "89870.00",
      "mark_close": "90120.00",
      "idx_open": "90000.00",
      "idx_high": "90250.00",
      "idx_low": "89860.00",
      "idx_close": "90100.00",
      "basis_bps_open": "1.33",
      "basis_bps_high": "3.32",
      "basis_bps_low": "1.11",
      "basis_bps_close": "2.22",
      "mark_minus_idx_close": "20.00",
      "premium_recomputed": null,
      "ticks": 60
    }
  ],
  "has_more": true,
  "next_from_s": 1759363200
}
```

## Related

* [Open-interest history](https://docs.bravadotrade.com/api/perps-data/oi-history.md) — OHLC of open interest with the same parameters and ranges.
* [Perps Data overview](https://docs.bravadotrade.com/products/perps-data.md) — the product, its credential and shared conventions.


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