> This page is for Documentation.

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://okx-demo.ferndocs.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://okx-demo.ferndocs.com/_mcp/server.

## Market data

* Added `GET /api/v5/market/history-mark-price-candles` for historical mark
  price candlesticks, complementing the existing index and trade-price candle
  endpoints.
* The order book endpoint `GET /api/v5/market/books` now accepts a `sz` value
  up to `400` for spot and margin instruments (previously `400` was restricted
  to specific instrument types).
* New WebSocket channel `mark-price-candle{bar}` delivers mark price candles in
  real time, matching the request-cadence of `index-candle{bar}`.