Massive computes the Greeks rather than receiving them, because no exchange publishes them, and that is why they appear on the options snapshot rather than on any historical endpoint. A contract whose Greeks cannot be computed comes back with an empty greeks object and no implied_volatility. On an index option chain those are out-of-the-money contracts with a zero bid, and that is not a gap in coverage.

Applies to

• Plans: an Options subscription. Greeks are computed values, so they are returned wherever the snapshot is available to your plan.
• Endpoints: /v3/snapshot/options/{underlyingAsset} for the chain and its Greeks; /v3/reference/options/contracts for contract definitions.
• Asset classes: index options, including SPX, NDX, VIX and RUT.

How to get Greeks for an index option

curl -X GET "https://api.massive.com/v3/snapshot/options/I:SPX/O:SPX261218C07600000?apiKey=YOUR_API_KEY"

Response

{
  "results": {
    "details": {
      "contract_type": "call",
      "exercise_style": "european",
      "expiration_date": "2026-12-18",
      "shares_per_contract": 100,
      "strike_price": 7600,
      "ticker": "O:SPX261218C07600000"
    },
    "greeks": {
      "delta": 0.5756070903107013,
      "gamma": 0.0006687038312778793,
      "theta": -1.665812044430241,
      "vega": 15.103468903725092
    },
    "implied_volatility": 0.15387520802176716,
    "open_interest": 24211,
    "underlying_asset": { "ticker": "I:SPX", "value": 7619.98 }
  },
  "status": "OK"
}

Filter the chain down before you read it. An index chain is large, so strike_price, expiration_date.gte and contract_type will save you paging through thousands of contracts to reach the one you want.

Which prefix each endpoint expects

The prefix differs between the snapshot and reference families, and getting it wrong does not return an error on either. The reference endpoint returns an empty result, and the snapshot returns the chain with no Greeks on any contract:

Passing I:SPX to the reference endpoint returns "status": "OK" with zero results, so that is where the prefix costs you the chain. Passing SPX to the snapshot costs you the Greeks and implied volatility instead.

Why the Greeks are computed rather than published

The Greeks are computed because no exchange publishes them. An exchange publishes trades and quotes; delta, gamma, theta and vega are model outputs derived from the option's price, the underlying's price, the time to expiry and an implied volatility solved from the same inputs. Massive computes them continuously from the live quote, which is why they appear on the snapshot rather than on a historical endpoint. Implied volatility is solved from the bid/ask midpoint. Index options are European, as exercise_style shows above, and unlike a stock option, an in-the-money index option whose midpoint is below its intrinsic value still returns Greeks.

If you see an error

"status": "OK" with an empty results array from the snapshot means a filter excluded everything, or the underlying has no chain. It is not the prefix: the bare form returns the same contracts, only without Greeks. Drop the filters, confirm you get contracts, then add them back.

An empty greeks object on every contract in an index option chain is what the bare symbol returns. Ask for /v3/snapshot/options/I:SPX rather than /v3/snapshot/options/SPX.

An empty greeks object on a few contracts, with Greeks on the rest, is an out-of-the-money contract with a zero bid. Some of those come back with Greeks and some without, so it is not an error in your request.

{"status":"NOT_AUTHORIZED","message":"You are not entitled to this data..."} means your plan does not include Options. Greeks come with the Options subscription, not with Indices.

Related

• Why are greeks and implied volatility missing from the options snapshot?
• Does Massive support options data for index contracts?
• What is implied volatility (IV)?
• How do you read an options symbol?
• Where does Massive source their indices data?
• Why am I not authorized (NOT_AUTHORIZED) when calling Massive's REST API or WebSockets?