Ticker updates

{
  "instrument_id": "<string>",
  "best_bid": 123,
  "best_ask": 123,
  "spread": 123,
  "mid_price": 123,
  "spot_price": 123,
  "greeks": {
    "delta": 123,
    "gamma": 123,
    "theta": 123,
    "vega": 123,
    "rho": 123,
    "iv": 123,
    "lambda": 123,
    "pop": 123
  }
}