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

# Basis History

> The perp's premium/discount to spot over time: mark - index (absolute and in bps), from the ticker snapshots.

The perp's premium or discount to spot over time — mark minus index, as an absolute number and in basis points — from the ticker snapshots. Complements the live [screener](/perps/market-data/screener). Bound with `after` / `before`.


## OpenAPI

````yaml GET /v3/perps/basis/{instrument}
openapi: 3.1.0
info:
  title: PolyNode API
  description: >-
    Real-time Polymarket data API with decoded mempool settlements, OHLCV
    candles, and full Polygon JSON-RPC proxy.
  contact:
    name: PolyNode
    url: https://polynode.dev
  license:
    name: ''
  version: 2.0.0
servers:
  - url: https://api.polynode.dev
    description: Production
security:
  - api_key: []
paths:
  /v3/perps/basis/{instrument}:
    get:
      tags:
        - Perps
      summary: Basis history
      description: >-
        The perp's premium/discount to spot over time: mark - index (absolute
        and in bps), from the ticker snapshots.
      parameters:
        - name: instrument
          in: path
          required: true
          description: Instrument id (6), symbol (BTC-USD), or bare asset (btc).
          schema:
            type: string
        - name: after
          in: query
          required: false
          description: Only rows after this time (Unix s or ms).
          schema:
            type: string
        - name: before
          in: query
          required: false
          description: Only rows before this time (Unix s or ms).
          schema:
            type: string
        - name: limit
          in: query
          required: false
          description: Max rows.
          schema:
            type: integer
      responses:
        '200':
          description: Success
          content:
            application/json:
              example:
                instrument_id: 6
                symbol: BTC-USD
                data:
                  - ts: 1783614397400
                    mark_price: '62511'
                    index_price: '62538'
                    basis: '-27.000000'
                    basis_bps: '-4.32'
components:
  securitySchemes:
    api_key:
      type: apiKey
      in: header
      name: x-api-key

````