curl --request GET \
  --url https://api.example.com/orderbook/{marketId}/spread

{
  "marketId": "<string>",
  "venues": [
    {
      "venue": "<string>",
      "bestBid": 123,
      "bestAsk": 123,
      "spread": 123,
      "midpoint": 123,
      "bidDepth": 123,
      "askDepth": 123
    }
  ],
  "bestBidVenue": "<string>",
  "bestAskVenue": "<string>",
  "tightestSpreadVenue": "<string>"
}